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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S I N F O --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2022, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package documents the structure of the abstract syntax tree. The Atree
-- package provides a basic tree structure. Sinfo describes how this structure
-- is used to represent the syntax of an Ada program.
-- The grammar in the RM is followed very closely in the tree design, and is
-- repeated as part of this source file.
-- The tree contains not only the full syntactic representation of the
-- program, but also the results of semantic analysis. In particular, the
-- nodes for defining identifiers, defining character literals, and defining
-- operator symbols, collectively referred to as entities, represent what
-- would normally be regarded as the symbol table information. In addition a
-- number of the tree nodes contain semantic information.
-- See the spec of Gen_IL.Gen for instructions on making changes to this file.
-- Note that the official definition of what nodes have what fields is in
-- Gen_IL.Gen.Gen_Nodes; if there is a discrepancy between that and the
-- comments here, Gen_IL.Gen.Gen_Nodes wins.
pragma Warnings (Off); -- with/use clauses for children
with Namet; use Namet;
with Types; use Types;
with Uintp; use Uintp;
with Urealp; use Urealp;
pragma Warnings (On);
package Sinfo is
----------------------------------------
-- Definitions of fields in tree node --
----------------------------------------
-- The following fields are common to all nodes:
-- Nkind Indicates the kind of the node. This field is present
-- in all nodes.
-- Sloc Location (Source_Ptr) of the corresponding token
-- in the Source buffer. The individual node definitions
-- show which token is referenced by this pointer.
-- In_List A flag used to indicate if the node is a member
-- of a node list (see package Nlists).
-- Rewrite_Ins A flag set if a node is marked as a rewrite inserted
-- node as a result of a call to Mark_Rewrite_Insertion.
-- Small_Paren_Count
-- A 2-bit count used in subexpression nodes to indicate
-- the level of parentheses. The settings are 0,1,2 and
-- 3 for many. If the value is 3, then an auxiliary table
-- is used to indicate the real value, which is computed by
-- Paren_Count. Set to zero for nonsubexpression nodes.
-- Note: the required parentheses surrounding conditional
-- and quantified expressions count as a level of parens
-- for this purpose, so e.g. in X := (if A then B else C);
-- Paren_Count for the right side will be 1.
-- Comes_From_Source
-- This flag is present in all nodes. It is set if the
-- node is built by the scanner or parser, and clear if
-- the node is built by the analyzer or expander. It
-- indicates that the node corresponds to a construct
-- that appears in the original source program.
-- Analyzed This flag is present in all nodes. It is set when
-- a node is analyzed, and is used to avoid analyzing
-- the same node twice. Analysis includes expansion if
-- expansion is active, so in this case if the flag is
-- set it means the node has been analyzed and expanded.
-- Error_Posted This flag is present in all nodes. It is set when
-- an error message is posted which is associated with
-- the flagged node. This is used to avoid posting more
-- than one message on the same node.
-- Link For a node, points to the Parent. For a list, points
-- to the list header. Note that in the latter case, a
-- client cannot modify the link field. This field is
-- private to the Atree package (but is also modified
-- by the Nlists package).
-- The following additional fields are common to all entities (that is,
-- nodes whose Nkind is in N_Entity):
-- Ekind Entity type.
-- Convention Entity convention (Convention_Id value)
--------------------------------
-- Implicit Nodes in the Tree --
--------------------------------
-- Generally the structure of the tree very closely follows the grammar as
-- defined in the RM. However, certain nodes are omitted to save space and
-- simplify semantic processing. Two general classes of such omitted nodes
-- are as follows:
-- If the only possibilities for a non-terminal are one or more other
-- non-terminals (i.e. the rule is a "skinny" rule), then usually the
-- corresponding node is omitted from the tree, and the target construct
-- appears directly. For example, a real type definition is either
-- floating point definition or a fixed point definition. No explicit node
-- appears for real type definition. Instead either the floating point
-- definition or fixed point definition appears directly.
-- If a non-terminal corresponds to a list of some other non-terminal
-- (possibly with separating punctuation), then usually it is omitted from
-- the tree, and a list of components appears instead. For example,
-- sequence of statements does not appear explicitly in the tree. Instead
-- a list of statements appears directly.
-- Some additional cases of omitted nodes occur and are documented
-- individually. In particular, many nodes are omitted in the tree
-- generated for an expression.
-------------------------------------------
-- Handling of Defining Identifier Lists --
-------------------------------------------
-- In several declarative forms in the syntax, lists of defining
-- identifiers appear (object declarations, component declarations, number
-- declarations etc.)
-- The semantics of such statements are equivalent to a series of identical
-- declarations of single defining identifiers (except that conformance
-- checks require the same grouping of identifiers in the parameter case).
-- To simplify semantic processing, the parser breaks down such multiple
-- declaration cases into sequences of single declarations, duplicating
-- type and initialization information as required. The flags More_Ids and
-- Prev_Ids are used to record the original form of the source in the case
-- where the original source used a list of names, More_Ids being set on
-- all but the last name and Prev_Ids being set on all but the first name.
-- These flags are used to reconstruct the original source (e.g. in the
-- Sprint package), and also are included in the conformance checks, but
-- otherwise have no semantic significance.
-- Note: the reason that we use More_Ids and Prev_Ids rather than
-- First_Name and Last_Name flags is so that the flags are off in the
-- normal one identifier case, which minimizes tree print output.
-----------------------
-- Use of Node Lists --
-----------------------
-- With a few exceptions, if a construction of the form {non-terminal}
-- appears in the tree, lists are used in the corresponding tree node (see
-- package Nlists for handling of node lists). In this case a field of the
-- parent node points to a list of nodes for the non-terminal. The field
-- name for such fields has a plural name which always ends in "s". For
-- example, a case statement has a field Alternatives pointing to list of
-- case statement alternative nodes.
-- Only fields pointing to lists have names ending in "s", so generally the
-- structure is strongly typed, fields not ending in s point to single
-- nodes, and fields ending in s point to lists.
-- The following example shows how a traversal of a list is written. We
-- suppose here that Stmt points to a N_Case_Statement node which has a
-- list field called Alternatives:
-- Alt := First (Alternatives (Stmt));
-- while Present (Alt) loop
-- ..
-- -- processing for case statement alternative Alt
-- ..
-- Alt := Next (Alt);
-- end loop;
-- The Present function tests for Empty, which in this case signals the end
-- of the list. First returns Empty immediately if the list is empty.
-- Present is defined in Atree; First and Next are defined in Nlists.
-- The exceptions to this rule occur with {DEFINING_IDENTIFIERS} in all
-- contexts, which is handled as described in the previous section, and
-- with {,library_unit_NAME} in the N_With_Clause node, which is handled
-- using the First_Name and Last_Name flags, as further detailed in the
-- description of the N_With_Clause node.
-------------
-- Pragmas --
-------------
-- Pragmas can appear in many different context, but are not included in
-- the grammar. Still they must appear in the tree, so they can be properly
-- processed.
-- Two approaches are used. In some cases, an extra field is defined in an
-- appropriate node that contains a list of pragmas appearing in the
-- expected context. For example pragmas can appear before an
-- Accept_Alternative in a Selective_Accept_Statement, and these pragmas
-- appear in the Pragmas_Before field of the N_Accept_Alternative node.
-- The other approach is to simply allow pragmas to appear in syntactic
-- lists where the grammar (of course) does not include the possibility.
-- For example, the Variants field of an N_Variant_Part node points to a
-- list that can contain both N_Pragma and N_Variant nodes.
-- To make processing easier in the latter case, the Nlists package
-- provides a set of routines (First_Non_Pragma, Last_Non_Pragma,
-- Next_Non_Pragma, Prev_Non_Pragma) that allow such lists to be handled
-- ignoring all pragmas.
-- In the case of the variants list, we can either write:
-- Variant := First (Variants (N));
-- while Present (Variant) loop
-- ...
-- Variant := Next (Variant);
-- end loop;
-- or
-- Variant := First_Non_Pragma (Variants (N));
-- while Present (Variant) loop
-- ...
-- Variant := Next_Non_Pragma (Variant);
-- end loop;
-- In the first form of the loop, Variant can either be an N_Pragma or an
-- N_Variant node. In the second form, Variant can only be N_Variant since
-- all pragmas are skipped.
---------------------
-- Optional Fields --
---------------------
-- Fields which correspond to a section of the syntax enclosed in square
-- brackets are generally omitted (and the corresponding field set to Empty
-- for a node, or No_List for a list). The documentation of such fields
-- notes these cases. One exception to this rule occurs in the case of
-- possibly empty statement sequences (such as the sequence of statements
-- in an entry call alternative). Such cases appear in the syntax rules as
-- [SEQUENCE_OF_STATEMENTS] and the fields corresponding to such optional
-- statement sequences always contain an empty list (not No_List) if no
-- statements are present.
-- Note: the utility program that constructs the body and spec of the Nmake
-- package relies on the format of the comments to determine if a field
-- should have a default value in the corresponding make routine. The rule
-- is that if the first line of the description of the field contains the
-- string "(set to xxx if", then a default value of xxx is provided for
-- this field in the corresponding Make_yyy routine.
-----------------------------------
-- Note on Body/Spec Terminology --
-----------------------------------
-- In informal discussions about Ada, it is customary to refer to package
-- and subprogram specs and bodies. However, this is not technically
-- correct, what is normally referred to as a spec or specification is in
-- fact a package declaration or subprogram declaration. We are careful in
-- GNAT to use the correct terminology and in particular, the full word
-- specification is never used as an incorrect substitute for declaration.
-- The structure and terminology used in the tree also reflects the grammar
-- and thus uses declaration and specification in the technically correct
-- manner.
-- However, there are contexts in which the informal terminology is useful.
-- We have the word "body" to refer to the Interp_Etype declared by the
-- declaration of a unit body, and in some contexts we need similar term to
-- refer to the entity declared by the package or subprogram declaration,
-- and simply using declaration can be confusing since the body also has a
-- declaration.
-- An example of such a context is the link between the package body and
-- its declaration. With_Declaration is confusing, since the package body
-- itself is a declaration.
-- To deal with this problem, we reserve the informal term Spec, i.e. the
-- popular abbreviation used in this context, to refer to the entity
-- declared by the package or subprogram declaration. So in the above
-- example case, the field in the body is called With_Spec.
-- Another important context for the use of the word Spec is in error
-- messages, where a hyper-correct use of declaration would be confusing to
-- a typical Ada programmer, and even for an expert programmer can cause
-- confusion since the body has a declaration as well.
-- So, to summarize:
-- Declaration always refers to the syntactic entity that is called
-- a declaration. In particular, subprogram declaration
-- and package declaration are used to describe the
-- syntactic entity that includes the semicolon.
-- Specification always refers to the syntactic entity that is called
-- a specification. In particular, the terms procedure
-- specification, function specification, package
-- specification, subprogram specification always refer
-- to the syntactic entity that has no semicolon.
-- Spec is an informal term, used to refer to the entity
-- that is declared by a task declaration, protected
-- declaration, generic declaration, subprogram
-- declaration or package declaration.
-- This convention is followed throughout the GNAT documentation
-- both internal and external, and in all error message text.
------------------------
-- Internal Use Nodes --
------------------------
-- These are Node_Kind settings used in the internal implementation which
-- are not logically part of the specification.
-- N_Unused_At_Start
-- Completely unused entry at the start of the enumeration type. This
-- is inserted so that no legitimate value is zero, which helps to get
-- better debugging behavior, since zero is a likely uninitialized value).
-- N_Unused_At_End
-- Completely unused entry at the end of the enumeration type. This is
-- handy so that arrays with Node_Kind as the index type have an extra
-- entry at the end (see for example the use of the Pchar_Pos_Array in
-- Treepr, where the extra entry provides the limit value when dealing with
-- the last used entry in the array).
-----------------------------------------
-- Note on the settings of Sloc fields --
-----------------------------------------
-- The Sloc field of nodes that come from the source is set by the parser.
-- For internal nodes, and nodes generated during expansion the Sloc is
-- usually set in the call to the constructor for the node. In general the
-- Sloc value chosen for an internal node is the Sloc of the source node
-- whose processing is responsible for the expansion. For example, the Sloc
-- of an inherited primitive operation is the Sloc of the corresponding
-- derived type declaration.
-- For the nodes of a generic instantiation, the Sloc value is encoded to
-- represent both the original Sloc in the generic unit, and the Sloc of
-- the instantiation itself. See Sinput.ads for details.
-- Subprogram instances create two callable entities: one is the visible
-- subprogram instance, and the other is an anonymous subprogram nested
-- within a wrapper package that contains the renamings for the actuals.
-- Both of these entities have the Sloc of the defining entity in the
-- instantiation node. This simplified for instance in the past some ASIS
-- queries.
-----------------------
-- Field Definitions --
-----------------------
-- In the following node definitions, all fields, both syntactic and
-- semantic, are documented. The one exception is in the case of entities
-- (defining identifiers, character literals, and operator symbols), where
-- the usage of the fields depends on the entity kind. Entity fields are
-- fully documented in the separate package Einfo.
-- In the node definitions, three common sets of fields are abbreviated to
-- save both space in the documentation, and also space in the string
-- (defined in Tree_Print_Strings) used to print trees. The following
-- abbreviations are used:
-- "plus fields for binary operator"
-- Chars Name_Id for the operator
-- Left_Opnd left operand expression
-- Right_Opnd right operand expression
-- Entity defining entity for operator
-- Associated_Node for generic processing
-- Do_Overflow_Check set if overflow check needed
-- Has_Private_View set in generic units.
-- "plus fields for unary operator"
-- Chars Name_Id for the operator
-- Right_Opnd right operand expression
-- Entity defining entity for operator
-- Associated_Node for generic processing
-- Do_Overflow_Check set if overflow check needed
-- Has_Private_View set in generic units.
-- "plus fields for expression"
-- Paren_Count number of parentheses levels
-- Etype type of the expression
-- Is_Overloaded >1 type interpretation exists
-- Is_Static_Expression set for static expression
-- Raises_Constraint_Error evaluation raises CE
-- Must_Not_Freeze set if must not freeze
-- Do_Range_Check set if a range check needed
-- Has_Dynamic_Length_Check set if length check inserted
-- Assignment_OK set if modification is OK
-- Is_Controlling_Actual set for controlling argument
-- Note: see under (EXPRESSION) for further details on the use of
-- the Paren_Count field to record the number of parentheses levels.
-- Node_Kind is the type used in the Nkind field to indicate the node kind.
-- The actual definition of this type is given later (the reason for this
-- is that we want the descriptions ordered by logical chapter in the RM,
-- but the type definition is reordered to facilitate the definition of
-- some subtype ranges. The individual descriptions of the nodes show how
-- the various fields are used in each node kind, as well as providing
-- logical names for the fields. Functions and procedures are provided for
-- accessing and setting these fields using these logical names.
-----------------------
-- Gigi Restrictions --
-----------------------
-- The tree passed to Gigi is more restricted than the general tree form.
-- For example, as a result of expansion, most of the tasking nodes can
-- never appear. For each node to which either a complete or partial
-- restriction applies, a note entitled "Gigi restriction" appears which
-- documents the restriction.
-- Note that most of these restrictions apply only to trees generated when
-- code is being generated, since they involved expander actions that
-- destroy the tree.
----------------
-- Ghost Mode --
----------------
-- The SPARK RM 6.9 defines two classes of constructs - Ghost entities and
-- Ghost statements. The intent of the feature is to treat Ghost constructs
-- as non-existent when Ghost assertion policy Ignore is in effect.
--
-- The corresponding nodes which map to Ghost constructs are:
--
-- Ghost entities
-- Declaration nodes
-- N_Package_Body
-- N_Subprogram_Body
--
-- Ghost statements
-- N_Assignment_Statement
-- N_Procedure_Call_Statement
-- N_Pragma
--
-- In addition, the compiler treats instantiations as Ghost entities
--
-- To achieve the removal of ignored Ghost constructs, the compiler relies
-- on global variables Ghost_Mode and Ignored_Ghost_Region, which comprise
-- a mechanism called "Ghost regions".
--
-- The values of Ghost_Mode are as follows:
--
-- 1. Check - All static semantics as defined in SPARK RM 6.9 are in
-- effect. The Ghost region has mode Check.
--
-- 2. Ignore - Same as Check, ignored Ghost code is not present in ALI
-- files, object files, and the final executable. The Ghost region
-- has mode Ignore.
--
-- 3. None - No Ghost region is in effect
--
-- The value of Ignored_Ghost_Region captures the node which initiates an
-- ignored Ghost region.
--
-- A Ghost region is a compiler operating mode, similar to Check_Syntax,
-- however a region is much more finely grained and depends on the policy
-- in effect. The region starts prior to the analysis of a Ghost construct
-- and ends immediately after its expansion. The region is established as
-- follows:
--
-- 1. Declarations - Prior to analysis, if the declaration is subject to
-- pragma Ghost.
--
-- 2. Renaming declarations - Same as 1) or when the renamed entity is
-- Ghost.
--
-- 3. Completing declarations - Same as 1) or when the declaration is
-- partially analyzed and the declaration completes a Ghost entity.
--
-- 4. N_Package_Body, N_Subprogram_Body - Same as 1) or when the body is
-- partially analyzed and completes a Ghost entity.
--
-- 5. N_Assignment_Statement - After the left hand side is analyzed and
-- references a Ghost entity.
--
-- 6. N_Procedure_Call_Statement - After the name is analyzed and denotes
-- a Ghost procedure.
--
-- 7. N_Pragma - During analysis, when the related entity is Ghost or the
-- pragma encloses a Ghost entity.
--
-- 8. Instantiations - Save as 1) or when the instantiation is partially
-- analyzed and the generic template is Ghost.
--
-- The following routines install a new Ghost region:
--
-- Install_Ghost_Region
-- Mark_And_Set_Ghost_xxx
-- Set_Ghost_Mode
--
-- The following routine ends a Ghost region:
--
-- Restore_Ghost_Region
--
-- A region may be reinstalled similarly to scopes for decoupled expansion
-- such as the generation of dispatch tables or the creation of a predicate
-- function.
--
-- If the mode of a Ghost region is Ignore, any newly created nodes as well
-- as source entities are marked as ignored Ghost. In additon, the marking
-- process signals all enclosing scopes that an ignored Ghost node resides
-- within. The compilation unit where the node resides is also added to an
-- auxiliary table for post processing.
--
-- After the analysis and expansion of all compilation units takes place
-- as well as the instantiation of all inlined [generic] bodies, the GNAT
-- driver initiates a separate pass which removes all ignored Ghost nodes
-- from all units stored in the auxiliary table.
--------------------
-- GNATprove Mode --
--------------------
-- When a file is compiled in GNATprove mode (-gnatd.F), a very light
-- expansion is performed and the analysis must generate a tree in a
-- form that meets additional requirements.
-- This light expansion does two transformations of the tree that cannot
-- be postponed till after semantic analysis:
-- 1. Replace object renamings by renamed object. This requires the
-- introduction of temporaries at the point of the renaming, which
-- must be properly analyzed.
-- 2. Fully qualify entity names. This is needed to generate suitable
-- local effects and call-graphs in ALI files, with the completely
-- qualified names (in particular the suffix to distinguish homonyms).
-- The tree after this light expansion should be fully analyzed
-- semantically, which sometimes requires the insertion of semantic
-- preanalysis, for example for subprogram contracts and pragma
-- check/assert. In particular, all expression must have their proper type,
-- and semantic links should be set between tree nodes (partial to full
-- view, etc.) Some kinds of nodes should be either absent, or can be
-- ignored by the formal verification backend:
-- N_Object_Renaming_Declaration: can be ignored safely
-- N_Expression_Function: absent (rewritten)
-- N_Expression_With_Actions: absent (not generated)
-- SPARK cross-references are generated from the regular cross-references
-- (used for browsing and code understanding) and additional references
-- collected during semantic analysis, in particular on all dereferences.
-- These SPARK cross-references are output in a separate section of ALI
-- files, as described in spark_xrefs.adb. They are the basis for the
-- computation of data dependences in GNATprove. This implies that all
-- cross-references should be generated in this mode, even those that would
-- not make sense from a user point-of-view, and that cross-references that
-- do not lead to data dependences for subprograms can be safely ignored.
-- GNATprove relies on the following front end behaviors:
-- 1. The first declarations in the list of visible declarations of
-- a package declaration for a generic instance, up to the first
-- declaration which comes from source, should correspond to
-- the "mappings nodes" between formal and actual generic parameters.
-- 2. In addition pragma Debug statements are removed from the tree
-- (rewritten to NULL stmt), since they should be ignored in formal
-- verification.
-- 3. An error is also issued for missing subunits, similar to the
-- warning issued when generating code, to avoid formal verification
-- of a partial unit.
-- 4. Unconstrained types are not replaced by constrained types whose
-- bounds are generated from an expression: Expand_Subtype_From_Expr
-- should be a no-op.
-- 5. Errors (instead of warnings) are issued on compile-time-known
-- constraint errors even though such cases do not correspond to
-- illegalities in the Ada RM (this is simply another case where
-- GNATprove implements a subset of the full language).
--
-- However, there are a few exceptions to this rule for cases where
-- we want to allow the GNATprove analysis to proceed (e.g. range
-- checks on empty ranges, which typically appear in deactivated
-- code in a particular configuration).
-- 6. Subtypes should match in the AST, even after a generic is
-- instantiated. In particular, GNATprove relies on the fact that,
-- on a selected component, the type of the selected component is
-- the type of the corresponding component in the prefix of the
-- selected component.
--
-- Note that, in some cases, we know that this rule is broken by the
-- frontend. In particular, if the selected component is a packed
-- array depending on a discriminant of a unconstrained formal object
-- parameter of a generic.
----------------
-- SPARK Mode --
----------------
-- The SPARK RM 1.6.5 defines a mode of operation called "SPARK mode" which
-- starts a scope where the SPARK language semantics are either On, Off, or
-- Auto, where Auto leaves the choice to the tools. A SPARK mode may be
-- specified by means of an aspect or a pragma.
-- The following entities may be subject to a SPARK mode. Entities marked
-- with * may possess two differente SPARK modes.
-- E_Entry
-- E_Entry_Family
-- E_Function
-- E_Generic_Function
-- E_Generic_Package *
-- E_Generic_Procedure
-- E_Operator
-- E_Package *
-- E_Package_Body *
-- E_Procedure
-- E_Protected_Body
-- E_Protected_Subtype
-- E_Protected_Type *
-- E_Subprogram_Body
-- E_Task_Body
-- E_Task_Subtype
-- E_Task_Type *
-- E_Variable
-- In order to manage SPARK scopes, the compiler relies on global variables
-- SPARK_Mode and SPARK_Mode_Pragma and a mechanism called "SPARK regions."
-- Routines Install_SPARK_Mode and Set_SPARK_Mode create a new SPARK region
-- and routine Restore_SPARK_Mode ends a SPARK region. A region may be
-- reinstalled similarly to scopes.
-----------------------
-- Check Flag Fields --
-----------------------
-- The following flag fields appear in expression nodes:
-- Do_Division_Check
-- Do_Overflow_Check
-- Do_Range_Check
-- These three flags are always set by the front end during semantic
-- analysis, on expression nodes that may trigger the corresponding
-- check. The front end then inserts or not the check during expansion. In
-- particular, these flags should also be correctly set in GNATprove mode.
-- As a special case, the front end does not insert a Do_Division_Check
-- flag on float exponentiation expressions, for the case where the value
-- is 0.0 and the exponent is negative, although this case does lead to a
-- division check failure. As another special case, the front end does not
-- insert a Do_Range_Check on an allocator where the designated type is
-- scalar, and the designated type is more constrained than the type of the
-- initialized allocator value or the type of the default value for an
-- uninitialized allocator.
-- Note that the expander always takes care of the Do_Range_Check case, so
-- this flag will never be set in the expanded tree passed to the back end.
-- For the other two flags, the check can be generated either by the back
-- end or by the front end, depending on the setting of a target parameter.
-- Note that this accounts for all nodes that trigger the corresponding
-- checks, except for range checks on subtype_indications, which may be
-- required to check that a range_constraint is compatible with the given
-- subtype (RM 3.2.2(11)).
-- The following flag fields appear in various nodes:
-- Do_Discriminant_Check
-- Do_Length_Check
-- Do_Storage_Check
-- These flags are used in some specific cases by the front end, either
-- during semantic analysis or during expansion, and cannot be expected
-- to be set on all nodes that trigger the corresponding check.
------------------------
-- Common Flag Fields --
------------------------
-- The following flag fields appear in all nodes:
-- Analyzed
-- This flag is used to indicate that a node (and all its children) have
-- been analyzed. It is used to avoid reanalysis of a node that has
-- already been analyzed, both for efficiency and functional correctness
-- reasons.
-- Comes_From_Source
-- This flag is set if the node comes directly from an explicit construct
-- in the source. It is normally on for any nodes built by the scanner or
-- parser from the source program, with the exception that in a few cases
-- the parser adds nodes to normalize the representation (in particular
-- a null statement is added to a package body if there is no begin/end
-- initialization section.
--
-- Most nodes inserted by the analyzer or expander are not considered
-- as coming from source, so the flag is off for such nodes. In a few
-- cases, the expander constructs nodes closely equivalent to nodes
-- from the source program (e.g. the allocator built for build-in-place
-- case), and the Comes_From_Source flag is deliberately set.
-- Error_Posted
-- This flag is used to avoid multiple error messages being posted on or
-- referring to the same node. This flag is set if an error message
-- refers to a node or is posted on its source location, and has the
-- effect of inhibiting further messages involving this same node.
-----------------------
-- Modify_Tree_For_C --
-----------------------
-- If the flag Opt.Modify_Tree_For_C is set True, then the tree is modified
-- in ways that help match the semantics better with C, easing the task of
-- interfacing to C code generators (other than GCC, where the work is done
-- in gigi, and there is no point in changing that), and also making life
-- easier for Cprint in generating C source code.
-- The current modifications implemented are as follows:
-- N_Op_Rotate_Left, N_Op_Rotate_Right, N_Shift_Right_Arithmetic nodes
-- are eliminated from the tree (since these operations do not exist in
-- C), and the operations are rewritten in terms of logical shifts and
-- other logical operations that do exist in C. See Exp_Ch4 expansion
-- routines for these operators for details of the transformations made.
-- The right operand of N_Op_Shift_Right and N_Op_Shift_Left is always
-- less than the word size (since other values are not well-defined in
-- C). This is done using an explicit test if necessary.
-- Min and Max attributes are expanded into equivalent if expressions,
-- dealing properly with side effect issues.
-- Mod for signed integer types is expanded into equivalent expressions
-- using Rem (which is % in C) and other C-available operators.
-- Functions returning bounded arrays are transformed into procedures
-- with an extra out parameter, and the calls updated accordingly.
-- Aggregates are only kept unexpanded for object declarations, otherwise
-- they are systematically expanded into loops (for arrays) and
-- individual assignments (for records).
-- Unconstrained array types are handled by means of fat pointers.
-- Postconditions are inlined by the frontend since their body may have
-- references to itypes defined in the enclosing subprogram.
------------------------------------
-- Description of Semantic Fields --
------------------------------------
-- The meaning of the syntactic fields is generally clear from their names
-- without any further description, since the names are chosen to
-- correspond very closely to the syntax in the reference manual. This
-- section describes the usage of the semantic fields, which are used to
-- contain additional information determined during semantic analysis.
-- Accept_Handler_Records
-- This field is present only in an N_Accept_Alternative node. It is used
-- to temporarily hold the exception handler records from an accept
-- statement in a selective accept. These exception handlers will
-- eventually be placed in the Handler_Records list of the procedure
-- built for this accept (see Expand_N_Selective_Accept procedure in
-- Exp_Ch9 for further details).
-- Access_Types_To_Process
-- Present in N_Freeze_Entity nodes for Incomplete or private types.
-- Contains the list of access types which may require specific treatment
-- when the nature of the type completion is completely known. An example
-- of such treatment is the generation of the associated_final_chain.
-- Actions
-- This field contains a sequence of actions that are associated with the
-- node holding the field. See the individual node types for details of
-- how this field is used, as well as the description of the specific use
-- for a particular node type.
-- Activation_Chain_Entity
-- This is used in tree nodes representing task activators (blocks,
-- subprogram bodies, package declarations, and task bodies). It is
-- initially Empty, and then gets set to point to the entity for the
-- declared Activation_Chain variable when the first task is declared.
-- When tasks are declared in the corresponding declarative region this
-- entity is located by name (its name is always _Chain) and the declared
-- tasks are added to the chain. Note that N_Extended_Return_Statement
-- does not have this attribute, although it does have an activation
-- chain. This chain is used to store the tasks temporarily, and is not
-- used for activating them. On successful completion of the return
-- statement, the tasks are moved to the caller's chain, and the caller
-- activates them.
-- Acts_As_Spec
-- A flag set in the N_Subprogram_Body node for a subprogram body which
-- is acting as its own spec. In the case of a library-level subprogram
-- the flag is set as well on the parent compilation unit node.
-- Actual_Designated_Subtype
-- Present in N_Free_Statement and N_Explicit_Dereference nodes. If gigi
-- needs to known the dynamic constrained subtype of the designated
-- object, this attribute is set to that type. This is done for
-- N_Free_Statements for access-to-classwide types and access to
-- unconstrained packed array types, and for N_Explicit_Dereference when
-- the designated type is an unconstrained packed array and the
-- dereference is the prefix of a 'Size attribute reference.
-- Address_Warning_Posted
-- Present in N_Attribute_Definition nodes. Set to indicate that we have
-- posted a warning for the address clause regarding size or alignment
-- issues. Used to inhibit multiple redundant messages.
-- Aggregate_Bounds
-- Present in array N_Aggregate nodes. If the bounds of the aggregate are
-- known at compile time, this field points to an N_Range node with those
-- bounds. Otherwise Empty.
-- Alloc_For_BIP_Return
-- Present in N_Allocator nodes. True if the allocator is one of those
-- generated for a build-in-place return statement.
-- All_Others
-- Present in an N_Others_Choice node. This flag is set for an others
-- exception where all exceptions are to be caught, even those that are
-- not normally handled (in particular the tasking abort signal). This
-- is used for translation of the at end handler into a normal exception
-- handler.
-- Aspect_On_Partial_View
-- Present on an N_Aspect_Specification node. For an aspect that applies
-- to a type entity, indicates whether the specification appears on the
-- partial view of a private type or extension. Undefined for aspects
-- that apply to other entities.
-- Aspect_Rep_Item
-- Present in N_Aspect_Specification nodes. Points to the corresponding
-- pragma/attribute definition node used to process the aspect.
-- Assignment_OK
-- This flag is set in a subexpression node for an object, indicating
-- that the associated object can be modified, even if this would not
-- normally be permissible (either by direct assignment, or by being
-- passed as an out or in-out parameter). This is used by the expander
-- for a number of purposes, including initialization of constants and
-- limited type objects (such as tasks), setting discriminant fields,
-- setting tag values, etc. N_Object_Declaration nodes also have this
-- flag defined. Here it is used to indicate that an initialization
-- expression is valid, even where it would normally not be allowed
-- (e.g. where the type involved is limited). It is also used to stop
-- a Force_Evaluation call for an unchecked conversion, but this usage
-- is unclear and not documented ???
-- Associated_Node
-- Present in nodes that can denote an entity: identifiers, character
-- literals, operator symbols, expanded names, operator nodes, and
-- attribute reference nodes (all these nodes have an Entity field).
-- This field is also present in N_Aggregate, N_Selected_Component, and
-- N_Extension_Aggregate nodes. This field is used in generic processing
-- to create links between the generic template and the generic copy.
-- See Sem_Ch12.Get_Associated_Node for full details. Note that this
-- field overlaps Entity, which is fine, since, as explained in Sem_Ch12,
-- the normal function of Entity is not required at the point where the
-- Associated_Node is set. Note also, that in generic templates, this
-- means that the Entity field does not necessarily point to an Entity.
-- Since the back end is expected to ignore generic templates, this is
-- harmless.
-- Atomic_Sync_Required
-- This flag is set on a node for which atomic synchronization is
-- required for the corresponding reference or modification.
-- At_End_Proc
-- This field is present in an N_Handled_Sequence_Of_Statements node.
-- It contains an identifier reference for the cleanup procedure to be
-- called. See description of this node for further details.
-- Backwards_OK
-- A flag present in the N_Assignment_Statement node. It is used only
-- if the type being assigned is an array type, and is set if analysis
-- determines that it is definitely safe to do the copy backwards, i.e.
-- starting at the highest addressed element. This is the case if either
-- the operands do not overlap, or they may overlap, but if they do,
-- then the left operand is at a higher address than the right operand.
--
-- Note: If neither of the flags Forwards_OK or Backwards_OK is set, it
-- means that the front end could not determine that either direction is
-- definitely safe, and a runtime check may be required if the backend
-- cannot figure it out. If both flags Forwards_OK and Backwards_OK are
-- set, it means that the front end can assure no overlap of operands.
-- Body_To_Inline
-- Present in subprogram declarations. Denotes analyzed but unexpanded
-- body of subprogram, to be used when inlining calls. Present when the
-- subprogram has an Inline pragma and inlining is enabled. If the
-- declaration is completed by a renaming_as_body, and the renamed entity
-- is a subprogram, the Body_To_Inline is the name of that entity, which
-- is used directly in later calls to the original subprogram.
-- Body_Required
-- A flag that appears in the N_Compilation_Unit node indicating that
-- the corresponding unit requires a body. For the package case, this
-- indicates that a completion is required. In Ada 95, if the flag is not
-- set for the package case, then a body may not be present. In Ada 83,
-- if the flag is not set for the package case, then body is optional.
-- For a subprogram declaration, the flag is set except in the case where
-- a pragma Import or Interface applies, in which case no body is
-- permitted (in Ada 83 or Ada 95).
-- By_Ref
-- Present in N_Simple_Return_Statement and N_Extended_Return_Statement,
-- this flag is set when the returned expression is already allocated on
-- the secondary stack and thus the result is passed by reference rather
-- than copied another time.
-- Cleanup_Actions
-- Present in block statements created for transient blocks, contains
-- additional cleanup actions carried over from the transient scope.
-- Check_Address_Alignment
-- A flag present in N_Attribute_Definition clause for a 'Address
-- attribute definition. This flag is set if a dynamic check should be
-- generated at the freeze point for the entity to which this address
-- clause applies. The reason that we need this flag is that we want to
-- check for range checks being suppressed at the point where the
-- attribute definition clause is given, rather than testing this at the
-- freeze point.
-- Comes_From_Extended_Return_Statement
-- Present in N_Simple_Return_Statement nodes. True if this node was
-- constructed as part of the N_Extended_Return_Statement expansion.
-- Compile_Time_Known_Aggregate
-- Present in N_Aggregate nodes. Set for aggregates which can be fully
-- evaluated at compile time without raising constraint error. Such
-- aggregates can be passed as is to the back end without any expansion.
-- See Exp_Aggr for specific conditions under which this flag gets set.
-- Componentwise_Assignment
-- Present in N_Assignment_Statement nodes. Set for a record assignment
-- where all that needs doing is to expand it into component-by-component
-- assignments. This is used internally for the case of tagged types with
-- rep clauses, where we need to avoid recursion (we don't want to try to
-- generate a call to the primitive operation, because this is the case
-- where we are compiling the primitive operation). Note that when we are
-- expanding component assignments in this case, we never assign the _tag
-- field, but we recursively assign components of the parent type.
-- Condition_Actions
-- This field appears in else-if nodes and in the iteration scheme node
-- for while loops. This field is only used during semantic processing to
-- temporarily hold actions inserted into the tree. In the tree passed
-- to gigi, the condition actions field is always set to No_List. For
-- details on how this field is used, see the routine Insert_Actions in
-- package Exp_Util, and also the expansion routines for the relevant
-- nodes.
-- Context_Pending
-- This field appears in Compilation_Unit nodes, to indicate that the
-- context of the unit is being compiled. Used to detect circularities
-- that are not otherwise detected by the loading mechanism. Such
-- circularities can occur in the presence of limited and non-limited
-- with_clauses that mention the same units.
-- Controlling_Argument
-- This field is set in procedure and function call nodes if the call
-- is a dispatching call (it is Empty for a non-dispatching call). It
-- indicates the source of the call's controlling tag. For procedure
-- calls, the Controlling_Argument is one of the actuals. For function
-- that has a dispatching result, it is an entity in the context of the
-- call that can provide a tag, or else it is the tag of the root type
-- of the class. It can also specify a tag directly rather than being a
-- tagged object. The latter is needed by the implementations of AI-239
-- and AI-260.
-- Conversion_OK
-- A flag set on type conversion nodes to indicate that the conversion
-- is to be considered as being valid, even though it is the case that
-- the conversion is not valid Ada. This is used for attributes Enum_Rep,
-- Pos, Val, Fixed_Value and Integer_Value, for internal conversions done
-- for fixed-point operations, and for certain conversions for calls to
-- initialization procedures. If Conversion_OK is set, then Etype must be
-- set (the analyzer assumes that Etype has been set). For the case of
-- fixed-point operands, it also indicates that the conversion is to be
-- direct conversion of the underlying integer result, with no regard to
-- the small operand.
-- Convert_To_Return_False
-- Present in N_Raise_Expression nodes that appear in the body of the
-- special predicateM function used to test a predicate in the context
-- of a membership test, where raise expression results in returning a
-- value of False rather than raising an exception.
-- Corresponding_Aspect
-- Present in N_Pragma node. Used to point back to the source aspect from
-- the corresponding pragma. This field is Empty for source pragmas.
-- Corresponding_Body
-- This field is set in subprogram declarations, package declarations,
-- entry declarations of protected types, and in generic units. It points
-- to the defining entity for the corresponding body (NOT the node for
-- the body itself).
-- Corresponding_Entry_Body
-- Defined in N_Subprogram_Body. Set for subprogram bodies that implement
-- a protected type entry; points to the body for the entry.
-- Corresponding_Formal_Spec
-- This field is set in subprogram renaming declarations, where it points
-- to the defining entity for a formal subprogram in the case where the
-- renaming corresponds to a generic formal subprogram association in an
-- instantiation. The field is Empty if the renaming does not correspond
-- to such a formal association.
-- Corresponding_Generic_Association
-- This field is defined for object declarations and object renaming
-- declarations. It is set for the declarations within an instance that
-- map generic formals to their actuals. If set, the field points either
-- to a copy of a default expression for an actual of mode IN or to a
-- generic_association which is the original parent of the expression or
-- name appearing in the declaration. This simplifies GNATprove queries.
-- Corresponding_Integer_Value
-- This field is set in real literals of fixed-point types (it is not
-- used for floating-point types). It contains the integer value used
-- to represent the fixed-point value. It is also set on the universal
-- real literals used to represent bounds of fixed-point base types
-- and their first named subtypes.
-- Corresponding_Spec
-- This field is set in subprogram, package, task, and protected body
-- nodes, where it points to the defining entity in the corresponding
-- spec. The attribute is also set in N_With_Clause nodes where it points
-- to the defining entity for the with'ed spec, and in a subprogram
-- renaming declaration when it is a Renaming_As_Body. The field is Empty
-- if there is no corresponding spec, as in the case of a subprogram body
-- that serves as its own spec.
--
-- In Ada 2012, Corresponding_Spec is set on expression functions that
-- complete a subprogram declaration.
-- Corresponding_Spec_Of_Stub
-- This field is present in subprogram, package, task, and protected body
-- stubs where it points to the corresponding spec of the stub. Due to
-- clashes in the structure of nodes, we cannot use Corresponding_Spec.
-- Corresponding_Stub
-- This field is present in an N_Subunit node. It holds the node in
-- the parent unit that is the stub declaration for the subunit. It is
-- set when analysis of the stub forces loading of the proper body. If
-- expansion of the proper body creates new declarative nodes, they are
-- inserted at the point of the corresponding_stub.
-- Dcheck_Function
-- This field is present in an N_Variant node, It references the entity
-- for the discriminant checking function for the variant.
-- Default_Expression
-- This field is Empty if there is no default expression. If there is a
-- simple default expression (one with no side effects), then this field
-- simply contains a copy of the Expression field (both point to the tree
-- for the default expression). Default_Expression is used for
-- conformance checking.
-- Default_Storage_Pool
-- This field is present in N_Compilation_Unit_Aux nodes. It is set to a
-- copy of Opt.Default_Pool at the end of the compilation unit. See
-- package Opt for details. This is used for inheriting the
-- Default_Storage_Pool in child units.
-- Discr_Check_Funcs_Built
-- This flag is present in N_Full_Type_Declaration nodes. It is set when
-- discriminant checking functions are constructed. The purpose is to
-- avoid attempting to set these functions more than once.
-- Do_Discriminant_Check
-- This flag is set on N_Selected_Component nodes to indicate that a
-- discriminant check is required using the discriminant check routine
-- associated with the selector. The actual check is generated by the
-- expander when processing selected components. In the case of
-- Unchecked_Union, the flag is also set, but no discriminant check
-- routine is associated with the selector, and the expander does not
-- generate a check. This flag is also present in assignment statements
-- (and set if the assignment requires a discriminant check), and in type
-- conversion nodes (and set if the conversion requires a check).
-- Do_Division_Check
-- This flag is set on a division operator (/ mod rem) to indicate that
-- a zero divide check is required. The actual check is either dealt with
-- by the back end if Backend_Divide_Checks is set to true, or by the
-- front end itself if it is set to false.
-- Do_Length_Check
-- This flag is set in an N_Assignment_Statement, N_Op_And, N_Op_Or,
-- N_Op_Xor, or N_Type_Conversion node to indicate that a length check
-- is required. It is not determined who deals with this flag (???).
-- Do_Overflow_Check
-- This flag is set on an operator where an overflow check is required on
-- the operation. The actual check is either dealt with by the back end
-- if Backend_Overflow_Checks is set to true, or by the front end itself
-- if it is set to false. The other cases where this flag is used is on a
-- Type_Conversion node as well on if and case expression nodes.
-- For a type conversion, it means that the conversion is from one base
-- type to another, and the value may not fit in the target base type.
-- See also the description of Do_Range_Check for this case. This flag is
-- also set on if and case expression nodes if we are operating in either
-- MINIMIZED or ELIMINATED overflow checking mode (to make sure that we
-- properly process overflow checking for dependent expressions).
-- Do_Range_Check
-- This flag is set on an expression which appears in a context where a
-- range check is required. The target type is clear from the context.
-- The contexts in which this flag can appear are the following:
-- Right side of an assignment. In this case the target type is taken
-- from the left side of the assignment, which is referenced by the
-- Name of the N_Assignment_Statement node.
-- Subscript expressions in an indexed component. In this case the
-- target type is determined from the type of the array, which is
-- referenced by the Prefix of the N_Indexed_Component node.
-- Argument expression for a parameter, appearing either directly in
-- the Parameter_Associations list of a call or as the Expression of an
-- N_Parameter_Association node that appears in this list. In either
-- case, the check is against the type of the formal. Note that the
-- flag is relevant only in IN and IN OUT parameters, and will be
-- ignored for OUT parameters, where no check is required in the call,
-- and if a check is required on the return, it is generated explicitly
-- with a type conversion.
-- Initialization expression for the initial value in an object
-- declaration. In this case the Do_Range_Check flag is set on
-- the initialization expression, and the check is against the
-- range of the type of the object being declared. This includes the
-- cases of expressions providing default discriminant values, and
-- expressions used to initialize record components.
-- The expression of a type conversion. In this case the range check is
-- against the target type of the conversion. See also the use of
-- Do_Overflow_Check on a type conversion. The distinction is that the
-- overflow check protects against a value that is outside the range of
-- the target base type, whereas a range check checks that the
-- resulting value (which is a value of the base type of the target
-- type), satisfies the range constraint of the target type.
-- Note: when a range check is required in contexts other than those
-- listed above (e.g. in a return statement), an additional type
-- conversion node is introduced to represent the required check.
-- Do_Storage_Check
-- This flag is set in an N_Allocator node to indicate that a storage
-- check is required for the allocation, or in an N_Subprogram_Body node
-- to indicate that a stack check is required in the subprogram prologue.
-- The N_Allocator case is handled by the routine that expands the call
-- to the runtime routine. The N_Subprogram_Body case is handled by the
-- backend, and all the semantics does is set the flag.
-- Elaborate_Present
-- This flag is set in the N_With_Clause node to indicate that pragma
-- Elaborate pragma appears for the with'ed units.
-- Elaborate_All_Desirable
-- This flag is set in the N_With_Clause mode to indicate that the static
-- elaboration processing has determined that an Elaborate_All pragma is
-- desirable for correct elaboration for this unit.
-- Elaborate_All_Present
-- This flag is set in the N_With_Clause node to indicate that a
-- pragma Elaborate_All pragma appears for the with'ed units.
-- Elaborate_Desirable
-- This flag is set in the N_With_Clause mode to indicate that the static
-- elaboration processing has determined that an Elaborate pragma is
-- desirable for correct elaboration for this unit.
-- Else_Actions
-- This field is present in if expression nodes. During code
-- expansion we use the Insert_Actions procedure (in Exp_Util) to insert
-- actions at an appropriate place in the tree to get elaborated at the
-- right time. For if expressions, we have to be sure that the actions
-- for the Else branch are only elaborated if the condition is False.
-- The Else_Actions field is used as a temporary parking place for
-- these actions. The final tree is always rewritten to eliminate the
-- need for this field, so in the tree passed to Gigi, this field is
-- always set to No_List.
-- Enclosing_Variant
-- This field is present in the N_Variant node and identifies the Node_Id
-- corresponding to the immediately enclosing variant when the variant is
-- nested, and N_Empty otherwise. Set during semantic processing of the
-- variant part of a record type.
-- Entity
-- Appears in all direct names (identifiers, character literals, and
-- operator symbols), as well as expanded names, and attributes that
-- denote entities, such as 'Class. Points to entity for corresponding
-- defining occurrence. Set after name resolution. For identifiers in a
-- WITH list, the corresponding defining occurrence is in a separately
-- compiled file, and Entity must be set by the library Load procedure.
--
-- Note: During name resolution, the value in Entity may be temporarily
-- incorrect (e.g. during overload resolution, Entity is initially set to
-- the first possible correct interpretation, and then later modified if
-- necessary to contain the correct value after resolution).
--
-- Note: This field overlaps Associated_Node, which is used during
-- generic processing (see Sem_Ch12 for details). Note also that in
-- generic templates, this means that the Entity field does not always
-- point to an Entity. Since the back end is expected to ignore generic
-- templates, this is harmless.
--
-- Note: This field also appears in N_Attribute_Definition_Clause nodes.
-- It is used only for stream attributes definition clauses. In this
-- case, it denotes a (possibly dummy) subprogram entity that is declared
-- conceptually at the point of the clause. Thus the visibility of the
-- attribute definition clause (in the sense of 8.3(23) as amended by
-- AI-195) can be checked by testing the visibility of that subprogram.
--
-- Note: Normally the Entity field of an identifier points to the entity
-- for the corresponding defining identifier, and hence the Chars field
-- of an identifier will match the Chars field of the entity. However,
-- there is no requirement that these match, and there are obscure cases
-- of generated code where they do not match.
-- Note: Ada 2012 aspect specifications require additional links between
-- identifiers and various attributes. These attributes can be of
-- arbitrary types, and the entity field of identifiers that denote
-- aspects must be used to store arbitrary expressions for later semantic
-- checks. See section on aspect specifications for details.
-- Entity_Or_Associated_Node
-- A synonym for both Entity and Associated_Node. Used by convention in
-- the code when referencing this field in cases where it is not known
-- whether the field contains an Entity or an Associated_Node.
-- Etype
-- Appears in all expression nodes, all direct names, and all entities.
-- Points to the entity for the related type. Set after type resolution.
-- Normally this is the actual subtype of the expression. However, in
-- certain contexts such as the right side of an assignment, subscripts,
-- arguments to calls, returned value in a function, initial value etc.
-- it is the desired target type. In the event that this is different
-- from the actual type, the Do_Range_Check flag will be set if a range
-- check is required. Note: if the Is_Overloaded flag is set, then Etype
-- points to an essentially arbitrary choice from the possible set of
-- types.
-- Exception_Junk
-- This flag is set in a various nodes appearing in a statement sequence
-- to indicate that the corresponding node is an artifact of the
-- generated code for exception handling, and should be ignored when
-- analyzing the control flow of the relevant sequence of statements
-- (e.g. to check that it does not end with a bad return statement).
-- Exception_Label
-- Appears in N_Push_xxx_Label nodes. Points to the entity of the label
-- to be used for transforming the corresponding exception into a goto,
-- or contains Empty, if this exception is not to be transformed. Also
-- appears in N_Exception_Handler nodes, where, if set, it indicates
-- that there may be a local raise for the handler, so that expansion
-- to allow a goto is required (and this field contains the label for
-- this goto). See Exp_Ch11.Expand_Local_Exception_Handlers for details.
-- Expansion_Delayed
-- Set on aggregates and extension aggregates that need a top-down rather
-- than bottom-up expansion. Typically aggregate expansion happens bottom
-- up. For nested aggregates the expansion is delayed until the enclosing
-- aggregate itself is expanded, e.g. in the context of a declaration. To
-- delay it we set this flag. This is done to avoid creating a temporary
-- for each level of a nested aggregate, and also to prevent the
-- premature generation of constraint checks. This is also a requirement
-- if we want to generate the proper attachment to the internal
-- finalization lists (for record with controlled components). Top down
-- expansion of aggregates is also used for in-place array aggregate
-- assignment or initialization. When the full context is known, the
-- target of the assignment or initialization is used to generate the
-- left-hand side of individual assignment to each subcomponent.
-- Expression_Copy
-- Present in N_Pragma_Argument_Association nodes. Contains a copy of the
-- original expression. This field is best used to store pragma-dependent
-- modifications performed on the original expression such as replacement
-- of the current type instance or substitutions of primitives.
-- First_Inlined_Subprogram
-- Present in the N_Compilation_Unit node for the main program. Points
-- to a chain of entities for subprograms that are to be inlined. The
-- Next_Inlined_Subprogram field of these entities is used as a link
-- pointer with Empty marking the end of the list. This field is Empty
-- if there are no inlined subprograms or inlining is not active.
-- First_Named_Actual
-- Present in procedure call statement and function call nodes, and also
-- in Intrinsic nodes. Set during semantic analysis to point to the first
-- named parameter where parameters are ordered by declaration order (as
-- opposed to the actual order in the call which may be different due to
-- named associations). Note: this field points to the explicit actual
-- parameter itself, not the N_Parameter_Association node (its parent).
-- First_Real_Statement
-- Present in N_Handled_Sequence_Of_Statements node. Normally set to
-- Empty. Used only when declarations are moved into the statement part
-- of a construct as a result of wrapping an AT END handler that is
-- required to cover the declarations. In this case, this field is used
-- to remember the location in the statements list of the first real
-- statement, i.e. the statement that used to be first in the statement
-- list before the declarations were prepended.
-- First_Subtype_Link
-- Present in N_Freeze_Entity node for an anonymous base type that is
-- implicitly created by the declaration of a first subtype. It points
-- to the entity for the first subtype.
-- Float_Truncate
-- A flag present in type conversion nodes. This is used for float to
-- integer conversions where truncation is required rather than rounding.
-- Forwards_OK
-- A flag present in the N_Assignment_Statement node. It is used only
-- if the type being assigned is an array type, and is set if analysis
-- determines that it is definitely safe to do the copy forwards, i.e.
-- starting at the lowest addressed element. This is the case if either
-- the operands do not overlap, or they may overlap, but if they do,
-- then the left operand is at a lower address than the right operand.
--
-- Note: If neither of the flags Forwards_OK or Backwards_OK is set, it
-- means that the front end could not determine that either direction is
-- definitely safe, and a runtime check may be required if the backend
-- cannot figure it out. If both flags Forwards_OK and Backwards_OK are
-- set, it means that the front end can assure no overlap of operands.
-- From_Aspect_Specification
-- Processing of aspect specifications typically results in insertion in
-- the tree of corresponding pragma or attribute definition clause nodes.
-- These generated nodes have the From_Aspect_Specification flag set to
-- indicate that they came from aspect specifications originally.
-- From_At_End
-- This flag is set on an N_Raise_Statement node if it corresponds to
-- the reraise statement generated as the last statement of an AT END
-- handler when SJLJ exception handling is active. It is used to stop
-- a bogus violation of restriction (No_Exception_Propagation), bogus
-- because if the restriction is set, the reraise is not generated.
-- From_At_Mod
-- This flag is set on the attribute definition clause node that is
-- generated by a transformation of an at mod phrase in a record
-- representation clause. This is used to give slightly different (Ada 83
-- compatible) semantics to such a clause, namely it is used to specify a
-- minimum acceptable alignment for the base type and all subtypes. In
-- Ada 95 terms, the actual alignment of the base type and all subtypes
-- must be a multiple of the given value, and the representation clause
-- is considered to be type specific instead of subtype specific.
-- From_Conditional_Expression
-- This flag is set on if and case statements generated by the expansion
-- of if and case expressions respectively. The flag is used to suppress
-- any finalization of controlled objects found within these statements.
-- From_Default
-- This flag is set on the subprogram renaming declaration created in an
-- instance for a formal subprogram, when the formal is declared with a
-- box, and there is no explicit actual. If the flag is present, the
-- declaration is treated as an implicit reference to the formal in the
-- ali file.
-- Generalized_Indexing
-- Present in N_Indexed_Component nodes. Set for Indexed_Component nodes
-- that are Ada 2012 container indexing operations. The value of the
-- attribute is a function call (possibly dereferenced) that corresponds
-- to the proper expansion of the source indexing operation. Before
-- expansion, the source node is rewritten as the resolved generalized
-- indexing.
-- Generic_Parent
-- Generic_Parent is defined on declaration nodes that are instances. The
-- value of Generic_Parent is the generic entity from which the instance
-- is obtained.
-- Generic_Parent_Type
-- Generic_Parent_Type is defined on Subtype_Declaration nodes for the
-- actuals of formal private and derived types. Within the instance, the
-- operations on the actual are those inherited from the parent. For a
-- formal private type, the parent type is the generic type itself. The
-- Generic_Parent_Type is also used in an instance to determine whether a
-- private operation overrides an inherited one.
-- Handler_List_Entry
-- This field is present in N_Object_Declaration nodes. It is set only
-- for the Handler_Record entry generated for an exception in zero cost
-- exception handling mode. It references the corresponding item in the
-- handler list, and is used to delete this entry if the corresponding
-- handler is deleted during optimization. For further details on why
-- this is required, see Exp_Ch11.Remove_Handler_Entries.
-- Has_Dereference_Action
-- This flag is present in N_Explicit_Dereference nodes. It is set to
-- indicate that the expansion has aready produced a call to primitive
-- Dereference of a System.Checked_Pools.Checked_Pool implementation.
-- Such dereference actions are produced for debugging purposes.
-- Has_Dynamic_Length_Check
-- This flag is present in all expression nodes. It is set to indicate
-- that one of the routines in unit Checks has generated a length check
-- action which has been inserted at the flagged node. This is used to
-- avoid the generation of duplicate checks.
-- Has_Local_Raise
-- Present in exception handler nodes. Set if the handler can be entered
-- via a local raise that gets transformed to a goto statement. This will
-- always be set if Local_Raise_Statements is non-empty, but can also be
-- set as a result of generation of N_Raise_xxx nodes, or flags set in
-- nodes requiring generation of back end checks.
-- Has_No_Elaboration_Code
-- A flag that appears in the N_Compilation_Unit node to indicate whether
-- or not elaboration code is present for this unit. It is initially set
-- true for subprogram specs and bodies and for all generic units and
-- false for non-generic package specs and bodies. Gigi may set the flag
-- in the non-generic package case if it determines that no elaboration
-- code is generated. Note that this flag is not related to the
-- Is_Preelaborated status, there can be preelaborated packages that
-- generate elaboration code, and non-preelaborated packages which do
-- not generate elaboration code.
-- Has_Pragma_Suppress_All
-- This flag is set in an N_Compilation_Unit node if the Suppress_All
-- pragma appears anywhere in the unit. This accommodates the rather
-- strange placement rules of other compilers (DEC permits it at the
-- end of a unit, and Rational allows it as a program unit pragma). We
-- allow it anywhere at all, and consider it equivalent to a pragma
-- Suppress (All_Checks) appearing at the start of the configuration
-- pragmas for the unit.
-- Has_Private_View
-- A flag present in generic nodes that have an entity, to indicate that
-- the node has a private type. Used to exchange private and full
-- declarations if the visibility at instantiation is different from the
-- visibility at generic definition.
-- Has_Relative_Deadline_Pragma
-- A flag present in N_Subprogram_Body and N_Task_Definition nodes to
-- flag the presence of a pragma Relative_Deadline.
-- Has_Self_Reference
-- Present in N_Aggregate and N_Extension_Aggregate. Indicates that one
-- of the expressions contains an access attribute reference to the
-- enclosing type. Such a self-reference can only appear in default-
-- initialized aggregate for a record type.
-- Has_SP_Choice
-- Present in all nodes containing a Discrete_Choices field (N_Variant,
-- N_Case_Expression_Alternative, N_Case_Statement_Alternative). Set to
-- True if the Discrete_Choices list has at least one occurrence of a
-- statically predicated subtype.
-- Has_Storage_Size_Pragma
-- A flag present in an N_Task_Definition node to flag the presence of a
-- Storage_Size pragma.
-- Has_Target_Names
-- Present in assignment statements. Indicates that the RHS contains
-- target names (see AI12-0125-3) and must be expanded accordingly.
-- Has_Wide_Character
-- Present in string literals, set if any wide character (i.e. character
-- code outside the Character range but within Wide_Character range)
-- appears in the string. Used to implement pragma preference rules.
-- Has_Wide_Wide_Character
-- Present in string literals, set if any wide character (i.e. character
-- code outside the Wide_Character range) appears in the string. Used to
-- implement pragma preference rules.
-- Header_Size_Added
-- Present in N_Attribute_Reference nodes, set only for attribute
-- Max_Size_In_Storage_Elements. The flag indicates that the size of the
-- hidden list header used by the runtime finalization support has been
-- added to the size of the prefix. The flag also prevents the infinite
-- expansion of the same attribute in the said context.
-- Hidden_By_Use_Clause
-- An entity list present in use clauses that appear within
-- instantiations. For the resolution of local entities, entities
-- introduced by these use clauses have priority over global ones,
-- and outer entities must be explicitly hidden/restored on exit.
-- Implicit_With
-- Present in N_With_Clause nodes. The flag indicates that the clause
-- does not comes from source and introduces an implicit dependency on
-- a particular unit. Such implicit with clauses are generated by:
--
-- * ABE mechanism - The static elaboration model of both the default
-- and the legacy ABE mechanism use with clauses to encode implicit
-- Elaborate[_All] pragmas.
--
-- * Analysis - A with clause for child unit A.B.C is equivalent to
-- a series of clauses that with A, A.B, and A.B.C. Manipulation of
-- contexts utilizes implicit with clauses to emulate the visibility
-- of a particular unit.
--
-- * RTSfind - The compiler generates code which references entities
-- from the runtime.
-- Import_Interface_Present
-- This flag is set in an Interface or Import pragma if a matching
-- pragma of the other kind is also present. This is used to avoid
-- generating some unwanted error messages.
-- Includes_Infinities
-- This flag is present in N_Range nodes. It is set for the range of
-- unconstrained float types defined in Standard, which include not only
-- the given range of values, but also legitimately can include infinite
-- values. This flag is false for any float type for which an explicit
-- range is given by the programmer, even if that range is identical to
-- the range for Float.
-- Incomplete_View
-- Present in full type declarations that are completions of incomplete
-- type declarations. Denotes the corresponding incomplete type
-- declaration. Used to simplify the retrieval of primitive operations
-- that may be declared between the partial and the full view of an
-- untagged type.
-- Inherited_Discriminant
-- This flag is present in N_Component_Association nodes. It indicates
-- that a given component association in an extension aggregate is the
-- value obtained from a constraint on an ancestor. Used to prevent
-- double expansion when the aggregate has expansion delayed.
-- Instance_Spec
-- This field is present in generic instantiation nodes, and also in
-- formal package declaration nodes (formal package declarations are
-- treated in a manner very similar to package instantiations). It points
-- to the node for the spec of the instance, inserted as part of the
-- semantic processing for instantiations in Sem_Ch12.
-- Is_Abort_Block
-- Present in N_Block_Statement nodes. True if the block protects a list
-- of statements with an Abort_Defer / Abort_Undefer_Direct pair.
-- Is_Accessibility_Actual
-- Present in N_Parameter_Association nodes. True if the parameter is
-- an extra actual that carries the accessibility level of the actual
-- for an access parameter, in a function that dispatches on result and
-- is called in a dispatching context. Used to prevent a formal/actual
-- mismatch when the call is rewritten as a dispatching call.
-- Is_Analyzed_Pragma
-- Present in N_Pragma nodes. Set for delayed pragmas that require a two
-- step analysis. The initial step is peformed by routine Analyze_Pragma
-- and verifies the overall legality of the pragma. The second step takes
-- place in the various Analyze_xxx_In_Decl_Part routines which perform
-- full analysis. The flag prevents the reanalysis of a delayed pragma.
-- Is_Asynchronous_Call_Block
-- A flag set in a Block_Statement node to indicate that it is the
-- expansion of an asynchronous entry call. Such a block needs cleanup
-- handler to assure that the call is cancelled.
-- Is_Boolean_Aspect
-- Present in N_Aspect_Specification node. Set if the aspect is for a
-- boolean aspect (i.e. Aspect_Id is in Boolean_Aspect subtype).
-- Is_Checked
-- Present in N_Aspect_Specification and N_Pragma nodes. Set for an
-- assertion aspect or pragma, or check pragma for an assertion, that
-- is to be checked at run time. If either Is_Checked or Is_Ignored
-- is set (they cannot both be set), then this means that the status of
-- the pragma has been checked at the appropriate point and should not
-- be further modified (in some cases these flags are copied when a
-- pragma is rewritten).
-- Is_Checked_Ghost_Pragma
-- This flag is present in N_Pragma nodes. It is set when the pragma is
-- related to a checked Ghost entity or encloses a checked Ghost entity.
-- This flag has no relation to Is_Checked.
-- Is_Component_Left_Opnd
-- Is_Component_Right_Opnd
-- Present in concatenation nodes, to indicate that the corresponding
-- operand is of the component type of the result. Used in resolving
-- concatenation nodes in instances.
-- Is_Controlling_Actual
-- This flag is set on an expression that is a controlling argument in
-- a dispatching call. It is off in all other cases. See Sem_Disp for
-- details of its use.
-- Is_Declaration_Level_Node
-- Present in call marker and instantiation nodes. Set when the constuct
-- appears within the declarations of a block statement, an entry body,
-- a subprogram body, or a task body. The flag aids the ABE Processing
-- phase to catch certain forms of guaranteed ABEs.
-- Is_Delayed_Aspect
-- Present in N_Pragma and N_Attribute_Definition_Clause nodes which
-- come from aspect specifications, where the evaluation of the aspect
-- must be delayed to the freeze point. This flag is also set True in
-- the corresponding N_Aspect_Specification node.
-- Is_Disabled
-- A flag set in an N_Aspect_Specification or N_Pragma node if there was
-- a Check_Policy or Assertion_Policy (or in the case of a Debug_Pragma)
-- a Debug_Policy pragma that resulted in totally disabling the flagged
-- aspect or policy as a result of using the GNAT-defined policy DISABLE.
-- If this flag is set, the aspect or policy is not analyzed for semantic
-- correctness, so any expressions etc will not be marked as analyzed.
-- Is_Dispatching_Call
-- Present in call marker nodes. Set when the related call which prompted
-- the creation of the marker is dispatching.
-- Is_Dynamic_Coextension
-- Present in allocator nodes, to indicate that this is an allocator
-- for an access discriminant of a dynamically allocated object. The
-- coextension must be deallocated and finalized at the same time as
-- the enclosing object. The partner flag Is_Static_Coextension must
-- be cleared before setting this flag to True.
-- Is_Effective_Use_Clause
-- Present in both N_Use_Type_Clause and N_Use_Package_Clause to indicate
-- a use clause is "used" in the current source.
-- Is_Elaboration_Checks_OK_Node
-- Present in the following nodes:
--
-- assignment statement
-- attribute reference
-- call marker
-- entry call statement
-- expanded name
-- function call
-- function instantiation
-- identifier
-- package instantiation
-- procedure call statement
-- procedure instantiation
-- requeue statement
-- variable reference marker
--
-- Set when the node appears within a context which allows the generation
-- of run-time ABE checks. This flag detemines whether the ABE Processing
-- phase generates conditional ABE checks and guaranteed ABE failures.
-- Is_Elaboration_Code
-- Present in assignment statements. Set for an assignment which updates
-- the elaboration flag of a package or subprogram when the corresponding
-- body is successfully elaborated.
-- Is_Elaboration_Warnings_OK_Node
-- Present in the following nodes:
--
-- attribute reference
-- call marker
-- entry call statement
-- expanded name
-- function call
-- function instantiation
-- identifier
-- package instantiation
-- procedure call statement
-- procedure instantiation
-- requeue statement
-- variable reference marker
--
-- Set when the node appears within a context where elaboration warnings
-- are enabled. This flag determines whether the ABE processing phase
-- generates diagnostics on various elaboration issues.
-- Is_Entry_Barrier_Function
-- This flag is set on N_Subprogram_Declaration and N_Subprogram_Body
-- nodes which emulate the barrier function of a protected entry body.
-- The flag is used when checking for incorrect use of Current_Task.
-- Is_Expanded_Build_In_Place_Call
-- This flag is set in an N_Function_Call node to indicate that the extra
-- actuals to support a build-in-place style of call have been added to
-- the call.
-- Is_Expanded_Contract
-- Present in N_Contract nodes. Set if the contract has already undergone
-- expansion activities.
-- Is_Finalization_Wrapper
-- This flag is present in N_Block_Statement nodes. It is set when the
-- block acts as a wrapper of a handled construct which has controlled
-- objects. The wrapper prevents interference between exception handlers
-- and At_End handlers.
-- Is_Generic_Contract_Pragma
-- This flag is present in N_Pragma nodes. It is set when the pragma is
-- a source construct, applies to a generic unit or its body, and denotes
-- one of the following contract-related annotations:
-- Abstract_State
-- Contract_Cases
-- Depends
-- Extensions_Visible
-- Global
-- Initial_Condition
-- Initializes
-- Post
-- Post_Class
-- Postcondition
-- Pre
-- Pre_Class
-- Precondition
-- Refined_Depends
-- Refined_Global
-- Refined_Post
-- Refined_State
-- Test_Case
-- Is_Homogeneous_Aggregate
-- A flag set on an Ada 2022 aggregate that uses square brackets as
-- delimiters, and thus denotes an array or container aggregate, or
-- the prefix of a reduction attribute.
-- Is_Ignored
-- A flag set in an N_Aspect_Specification or N_Pragma node if there was
-- a Check_Policy or Assertion_Policy (or in the case of a Debug_Pragma)
-- a Debug_Policy pragma that specified a policy of IGNORE, DISABLE, or
-- OFF, for the pragma/aspect. If there was a Policy pragma specifying
-- a Policy of ON or CHECK, then this flag is reset. If no Policy pragma
-- gives a policy for the aspect or pragma, then there are two cases. For
-- an assertion aspect or pragma (one of the assertion kinds allowed in
-- an Assertion_Policy pragma), then Is_Ignored is set if assertions are
-- ignored because of the absence of a -gnata switch. For any other
-- aspects or pragmas, the flag is off. If this flag is set, the
-- aspect/pragma is fully analyzed and checked for other syntactic
-- and semantic errors, but it does not have any semantic effect.
-- Is_Ignored_Ghost_Pragma
-- This flag is present in N_Pragma nodes. It is set when the pragma is
-- related to an ignored Ghost entity or encloses ignored Ghost entity.
-- This flag has no relation to Is_Ignored.
-- Is_In_Discriminant_Check
-- This flag is present in a selected component, and is used to indicate
-- that the reference occurs within a discriminant check. The
-- significance is that optimizations based on assuming that the
-- discriminant check has a correct value cannot be performed in this
-- case (or the discriminant check may be optimized away).
-- Is_Inherited_Pragma
-- This flag is set in an N_Pragma node that appears in a N_Contract node
-- to indicate that the pragma has been inherited from a parent context.
-- Is_Initialization_Block
-- Defined in block nodes. Set when the block statement was created by
-- the finalization machinery to wrap initialization statements. This
-- flag aids the ABE Processing phase to suppress the diagnostics of
-- finalization actions in initialization contexts.
-- Is_Known_Guaranteed_ABE
-- NOTE: this flag is shared between the legacy ABE mechanism and the
-- default ABE mechanism.
--
-- Present in the following nodes:
--
-- call marker
-- formal package declaration
-- function call
-- function instantiation
-- package instantiation
-- procedure call statement
-- procedure instantiation
--
-- Set when the elaboration or evaluation of the scenario results in
-- a guaranteed ABE. The flag is used to suppress the instantiation of
-- generic bodies because gigi cannot handle certain forms of premature
-- instantiation, as well as to prevent the reexamination of the node by
-- the ABE Processing phase.
-- Is_Machine_Number
-- This flag is set in an N_Real_Literal node to indicate that the value
-- is a machine number. This avoids some unnecessary cases of converting
-- real literals to machine numbers.
-- Is_Null_Loop
-- This flag is set in an N_Loop_Statement node if the corresponding loop
-- can be determined to be null at compile time. This is used to remove
-- the loop entirely at expansion time.
-- Is_Overloaded
-- A flag present in all expression nodes. Used temporarily during
-- overloading determination. The setting of this flag is not relevant
-- once overloading analysis is complete.
-- Is_Power_Of_2_For_Shift
-- A flag present only in N_Op_Expon nodes. It is set when the
-- exponentiation is of the form 2 ** N, where the type of N is an
-- unsigned integral subtype whose size does not exceed the size of
-- Standard_Integer (i.e. a type that can be safely converted to
-- Natural), and the exponentiation appears as the right operand of an
-- integer multiplication or an integer division where the dividend is
-- unsigned. It is also required that overflow checking is off for both
-- the exponentiation and the multiply/divide node. If this set of
-- conditions holds, and the flag is set, then the division or
-- multiplication can be (and is) converted to a shift.
-- Is_Preelaborable_Call
-- Present in call marker nodes. Set when the related call is non-static
-- but preelaborable.
-- Is_Prefixed_Call
-- This flag is set in a selected component within a generic unit, if
-- it resolves to a prefixed call to a primitive operation. The flag
-- is used to prevent accidental overloadings in an instance, when a
-- primitive operation and a private record component may be homographs.
-- Is_Protected_Subprogram_Body
-- A flag set in a Subprogram_Body block to indicate that it is the
-- implementation of a protected subprogram. Such a body needs cleanup
-- handler to make sure that the associated protected object is unlocked
-- when the subprogram completes.
-- Is_Qualified_Universal_Literal
-- Present in N_Qualified_Expression nodes. Set when the qualification is
-- converting a universal literal to a specific type. Such qualifiers aid
-- the resolution of accidental overloading of binary or unary operators
-- which may occur in instances.
-- Is_Read
-- Present in variable reference markers. Set when the original variable
-- reference constitutes a read of the variable.
-- Is_Source_Call
-- Present in call marker nodes. Set when the related call came from
-- source.
-- Is_SPARK_Mode_On_Node
-- Present in the following nodes:
--
-- assignment statement
-- attribute reference
-- call marker
-- entry call statement
-- expanded name
-- function call
-- function instantiation
-- identifier
-- package instantiation
-- procedure call statement
-- procedure instantiation
-- requeue statement
-- variable reference marker
--
-- Set when the node appears within a context subject to SPARK_Mode On.
-- This flag determines when the SPARK model of elaboration be activated
-- by the ABE Processing phase.
-- Is_Static_Coextension
-- Present in N_Allocator nodes. Set if the allocator is a coextension
-- of an object allocated on the stack rather than the heap. The partner
-- flag Is_Dynamic_Coextension must be cleared before setting this flag
-- to True.
-- Is_Static_Expression
-- Indicates that an expression is a static expression according to the
-- rules in RM-4.9. See Sem_Eval for details.
-- Is_Subprogram_Descriptor
-- Present in N_Object_Declaration, and set only for the object
-- declaration generated for a subprogram descriptor in fast exception
-- mode. See Exp_Ch11 for details of use.
-- Is_Task_Allocation_Block
-- A flag set in a Block_Statement node to indicate that it is the
-- expansion of a task allocator, or the allocator of an object
-- containing tasks. Such a block requires a cleanup handler to call
-- Expunge_Unactivated_Tasks to complete any tasks that have been
-- allocated but not activated when the allocator completes abnormally.
-- Is_Task_Body_Procedure
-- This flag is set on N_Subprogram_Declaration and N_Subprogram_Body
-- nodes which emulate the body of a task unit.
-- Is_Task_Master
-- A flag set in a Subprogram_Body, Block_Statement, or Task_Body node to
-- indicate that the construct is a task master (i.e. has declared tasks
-- or declares an access to a task type).
-- Is_Write
-- Present in variable reference markers. Set when the original variable
-- reference constitutes a write of the variable.
-- Itype
-- Used in N_Itype_Reference node to reference an itype for which it is
-- important to ensure that it is defined. See description of this node
-- for further details.
-- Kill_Range_Check
-- Used in an N_Unchecked_Type_Conversion node to indicate that the
-- result should not be subjected to range checks. This is used for the
-- implementation of Normalize_Scalars.
-- Label_Construct
-- Used in an N_Implicit_Label_Declaration node. Refers to an N_Label,
-- N_Block_Statement or N_Loop_Statement node to which the label
-- declaration applies. The field is left empty for the special labels
-- generated as part of expanding raise statements with a local exception
-- handler.
-- Library_Unit
-- In a stub node, Library_Unit points to the compilation unit node of
-- the corresponding subunit.
--
-- In a with clause node, Library_Unit points to the spec of the with'ed
-- unit.
--
-- In a compilation unit node, the usage depends on the unit type:
--
-- For a library unit body, Library_Unit points to the compilation unit
-- node of the corresponding spec, unless it's a subprogram body with
-- Acts_As_Spec set, in which case it points to itself.
--
-- For a spec, Library_Unit points to the compilation unit node of the
-- corresponding body, if present. The body will be present if the spec
-- is or contains generics that we needed to instantiate. Similarly, the
-- body will be present if we needed it for inlining purposes. Thus, if
-- we have a spec/body pair, both of which are present, they point to
-- each other via Library_Unit.
--
-- For a subunit, Library_Unit points to the compilation unit node of
-- the parent body.
-- ??? not (always) true, in (at least some, maybe all?) cases it points
-- to the corresponding spec for the parent body.
--
-- Note that this field is not used to hold the parent pointer for child
-- unit (which might in any case need to use it for some other purpose as
-- described above). Instead for a child unit, implicit with's are
-- generated for all parents.
-- Local_Raise_Statements
-- This field is present in exception handler nodes. It is set to
-- No_Elist in the normal case. If there is at least one raise statement
-- which can potentially be handled as a local raise, then this field
-- points to a list of raise nodes, which are calls to a routine to raise
-- an exception. These are raise nodes which can be optimized into gotos
-- if the handler turns out to meet the conditions which permit this
-- transformation. Note that this does NOT include instances of the
-- N_Raise_xxx_Error nodes since the transformation of these nodes is
-- handled by the back end (using the N_Push/N_Pop mechanism).
-- Loop_Actions
-- A list present in Component_Association nodes in array aggregates.
-- Used to collect actions that must be executed within the loop because
-- they may need to be evaluated anew each time through.
-- Limited_View_Installed
-- Present in With_Clauses and in package specifications. If set on
-- with_clause, it indicates that this clause has created the current
-- limited view of the designated package. On a package specification, it
-- indicates that the limited view has already been created because the
-- package is mentioned in a limited_with_clause in the closure of the
-- unit being compiled.
-- Local_Raise_Not_OK
-- Present in N_Exception_Handler nodes. Set if the handler contains
-- a construct (reraise statement, or call to subprogram in package
-- GNAT.Current_Exception) that makes the handler unsuitable as a target
-- for a local raise (one that could otherwise be converted to a goto).
-- Must_Be_Byte_Aligned
-- This flag is present in N_Attribute_Reference nodes. It can be set
-- only for the Address and Unrestricted_Access attributes. If set it
-- means that the object for which the address/access is given must be on
-- a byte (more accurately a storage unit) boundary. If necessary, a copy
-- of the object is to be made before taking the address (this copy is in
-- the current scope on the stack frame). This is used for certain cases
-- of code generated by the expander that passes parameters by address.
--
-- The reason the copy is not made by the front end is that the back end
-- has more information about type layout and may be able to (but is not
-- guaranteed to) prevent making unnecessary copies.
-- Must_Not_Freeze
-- A flag present in all expression nodes. Normally expressions cause
-- freezing as described in the RM. If this flag is set, then this is
-- inhibited. This is used by the analyzer and expander to label nodes
-- that are created by semantic analysis or expansion and which must not
-- cause freezing even though they normally would. This flag is also
-- present in an N_Subtype_Indication node, since we also use these in
-- calls to Freeze_Expression.
-- Next_Entity
-- Present in defining identifiers, defining character literals, and
-- defining operator symbols (i.e. in all entities). The entities of a
-- scope are chained, and this field is used as the forward pointer for
-- this list. See Einfo for further details.
-- Next_Exit_Statement
-- Present in N_Exit_Statement nodes. The exit statements for a loop are
-- chained (in reverse order of appearance) from the First_Exit_Statement
-- field of the E_Loop entity for the loop. Next_Exit_Statement points to
-- the next entry on this chain (Empty = end of list).
-- Next_Implicit_With
-- Present in N_With_Clause. Part of a chain of with_clauses generated
-- in rtsfind to indicate implicit dependencies on predefined units. Used
-- to prevent multiple with_clauses for the same unit in a given context.
-- A postorder traversal of the tree whose nodes are units and whose
-- links are with_clauses defines the order in which CodePeer must
-- examine a compiled unit and its full context. This ordering ensures
-- that any subprogram call is examined after the subprogram declaration
-- has been seen.
-- Next_Named_Actual
-- Present in parameter association nodes. Set during semantic analysis
-- to point to the next named parameter, where parameters are ordered by
-- declaration order (as opposed to the actual order in the call, which
-- may be different due to named associations). Not that this field
-- points to the explicit actual parameter itself, not to the
-- N_Parameter_Association node (its parent).
-- Next_Pragma
-- Present in N_Pragma nodes. Used to create a linked list of pragma
-- nodes. Currently used for two purposes:
--
-- Create a list of linked Check_Policy pragmas. The head of this list
-- is stored in Opt.Check_Policy_List (which has further details).
--
-- Used by processing for Pre/Postcondition pragmas to store a list of
-- pragmas associated with the spec of a subprogram (see Sem_Prag for
-- details).
--
-- Used by processing for pragma SPARK_Mode to store multiple pragmas
-- the apply to the same construct. These are visible/private mode for
-- a package spec and declarative/statement mode for package body.
-- Next_Rep_Item
-- Present in pragma nodes, attribute definition nodes, enumeration rep
-- clauses, record rep clauses, aspect specification and null statement
-- nodes. Used to link representation items that apply to an entity. See
-- full description of First_Rep_Item field in Einfo for further details.
-- Next_Use_Clause
-- While use clauses are active during semantic processing, they are
-- chained from the scope stack entry, using Next_Use_Clause as a link
-- pointer, with Empty marking the end of the list. The head pointer is
-- in the scope stack entry (First_Use_Clause). At the end of semantic
-- processing (i.e. when Gigi sees the tree, the contents of this field
-- is undefined and should not be read).
-- No_Ctrl_Actions
-- Present in N_Assignment_Statement to indicate that no Finalize nor
-- Adjust should take place on this assignment even though the RHS is
-- controlled. Also indicates that the primitive _assign should not be
-- used for a tagged assignment. This is used in init procs and aggregate
-- expansions where the generated assignments are initializations, not
-- real assignments.
-- No_Elaboration_Check
-- NOTE: this flag is relevant only for the legacy ABE mechanism and
-- should not be used outside of that context.
--
-- Present in N_Function_Call and N_Procedure_Call_Statement. Indicates
-- that no elaboration check is needed on the call, because it appears in
-- the context of a local Suppress pragma. This is used on calls within
-- task bodies, where the actual elaboration checks are applied after
-- analysis, when the local scope stack is not present.
-- No_Entities_Ref_In_Spec
-- Present in N_With_Clause nodes. Set if the with clause is on the
-- package or subprogram spec where the main unit is the corresponding
-- body, and no entities of the with'ed unit are referenced by the spec
-- (an entity may still be referenced in the body, so this flag is used
-- to generate the proper message (see Sem_Util.Check_Unused_Withs for
-- full details).
-- No_Initialization
-- Present in N_Object_Declaration and N_Allocator to indicate that the
-- object must not be initialized (by Initialize or call to an init
-- proc). This is needed for controlled aggregates. When the Object
-- declaration has an expression, this flag means that this expression
-- should not be taken into account (needed for in place initialization
-- with aggregates, and for object with an address clause, which are
-- initialized with an assignment at freeze time).
-- No_Minimize_Eliminate
-- This flag is present in membership operator nodes (N_In/N_Not_In).
-- It is used to indicate that processing for extended overflow checking
-- modes is not required (this is used to prevent infinite recursion).
-- No_Side_Effect_Removal
-- Present in N_Function_Call nodes. Set when a function call does not
-- require side effect removal. This attribute suppresses the generation
-- of a temporary to capture the result of the function which eventually
-- replaces the function call.
-- No_Truncation
-- Present in N_Unchecked_Type_Conversion node. This flag has an effect
-- only if the RM_Size of the source is greater than the RM_Size of the
-- target for scalar operands. Normally in such a case we truncate some
-- higher order bits of the source, and then sign/zero extend the result
-- to form the output value. But if this flag is set, then we do not do
-- any truncation, so for example, if an 8 bit input is converted to 5
-- bit result which is in fact stored in 8 bits, then the high order
-- three bits of the target result will be copied from the source. This
-- is used for properly setting out of range values for use by pragmas
-- Initialize_Scalars and Normalize_Scalars.
-- Null_Excluding_Subtype
-- Present in N_Access_To_Object_Definition. Indicates that the subtype
-- indication carries a null-exclusion indicator, which is distinct from
-- the null-exclusion indicator that may precede the access keyword.
-- Original_Discriminant
-- Present in identifiers. Used in references to discriminants that
-- appear in generic units. Because the names of the discriminants may be
-- different in an instance, we use this field to recover the position of
-- the discriminant in the original type, and replace it with the
-- discriminant at the same position in the instantiated type.
-- Original_Entity
-- Present in numeric literals. Used to denote the named number that has
-- been constant-folded into the given literal. If literal is from
-- source, or the result of some other constant-folding operation, then
-- Original_Entity is empty. This field is needed to handle properly
-- named numbers in generic units, where the Associated_Node field
-- interferes with the Entity field, making it impossible to preserve the
-- original entity at the point of instantiation.
-- Others_Discrete_Choices
-- When a case statement or variant is analyzed, the semantic checks
-- determine the actual list of choices that correspond to an others
-- choice. This list is materialized for later use by the expander and
-- the Others_Discrete_Choices field of an N_Others_Choice node points to
-- this materialized list of choices, which is in standard format for a
-- list of discrete choices, except that of course it cannot contain an
-- N_Others_Choice entry.
-- Parent_Spec
-- For a library unit that is a child unit spec (package or subprogram
-- declaration, generic declaration or instantiation, or library level
-- rename) this field points to the compilation unit node for the parent
-- package specification. This field is Empty for library bodies (the
-- parent spec in this case can be found from the corresponding spec).
-- Parent_With
-- Present in N_With_Clause nodes. The flag indicates that the clause
-- was generated for an ancestor unit to provide proper visibility. A
-- with clause for child unit A.B.C produces two implicit parent with
-- clauses for A and A.B.
-- Premature_Use
-- Present in N_Incomplete_Type_Declaration node. Used for improved
-- error diagnostics: if there is a premature usage of an incomplete
-- type, a subsequently generated error message indicates the position
-- of its full declaration.
-- Present_Expr
-- Present in an N_Variant node. This has a meaningful value only after
-- Gigi has back annotated the tree with representation information. At
-- this point, it contains a reference to a gcc expression that depends
-- on the values of one or more discriminants. Given a set of
-- discriminant values, this expression evaluates to False (zero) if
-- variant is not present, and True (non-zero) if it is present. See
-- unit Repinfo for further details on gigi back annotation. This field
-- is used during back-annotation processing (for -gnatR -gnatc) to
-- determine if a field is present or not.
-- Prev_Use_Clause
-- Present in both N_Use_Package_Clause and N_Use_Type_Clause. Used in
-- detection of ineffective use clauses by allowing a chain of related
-- clauses together to avoid traversing the current scope stack.
-- Print_In_Hex
-- Set on an N_Integer_Literal node to indicate that the value should be
-- printed in hexadecimal in the sprint listing. Has no effect on
-- legality or semantics of program, only on the displayed output. This
-- is used to clarify output from the packed array cases.
-- Procedure_To_Call
-- Present in N_Allocator, N_Free_Statement, N_Simple_Return_Statement,
-- and N_Extended_Return_Statement nodes. References the entity for the
-- declaration of the procedure to be called to accomplish the required
-- operation (i.e. for the Allocate procedure in the case of N_Allocator
-- and N_Simple_Return_Statement and N_Extended_Return_Statement (for
-- allocating the return value), and for the Deallocate procedure in the
-- case of N_Free_Statement.
-- Raises_Constraint_Error
-- Set on an expression whose evaluation will definitely fail constraint
-- error check. See Sem_Eval for details.
-- Redundant_Use
-- Present in nodes that can appear as an operand in a use clause or use
-- type clause (identifiers, expanded names, attribute references). Set
-- to indicate that a use is redundant (and therefore need not be undone
-- on scope exit).
-- Renaming_Exception
-- Present in N_Exception_Declaration node. Used to point back to the
-- exception renaming for an exception declared within a subprogram.
-- What happens is that an exception declared in a subprogram is moved
-- to the library level with a unique name, and the original exception
-- becomes a renaming. This link from the library level exception to the
-- renaming declaration allows registering of the proper exception name.
-- Return_Statement_Entity
-- Present in N_Simple_Return_Statement and N_Extended_Return_Statement.
-- Points to an E_Return_Statement representing the return statement.
-- Return_Object_Declarations
-- Present in N_Extended_Return_Statement. Points to a list initially
-- containing a single N_Object_Declaration representing the return
-- object. We use a list (instead of just a pointer to the object decl)
-- because Analyze wants to insert extra actions on this list, before the
-- N_Object_Declaration, which always remains last on the list.
-- Rounded_Result
-- Present in N_Type_Conversion, N_Op_Divide, and N_Op_Multiply nodes.
-- Used in the fixed-point cases to indicate that the result must be
-- rounded as a result of the use of the 'Round attribute. Also used for
-- integer N_Op_Divide nodes to indicate that the result should be
-- rounded to the nearest integer (breaking ties away from zero), rather
-- than truncated towards zero as usual. These rounded integer operations
-- are the result of expansion of rounded fixed-point divide, conversion
-- and multiplication operations.
-- Save_Invocation_Graph_Of_Body
-- Present in compilation unit nodes. Set when the elaboration mechanism
-- must record all invocation constructs and invocation relations within
-- the body of the compilation unit.
--
-- SCIL_Entity
-- Present in SCIL nodes. References the specific tagged type associated
-- with the SCIL node (for an N_SCIL_Dispatching_Call node, this is
-- the controlling type of the call; for an N_SCIL_Membership_Test node
-- generated as part of testing membership in T'Class, this is T; for an
-- N_SCIL_Dispatch_Table_Tag_Init node, this is the type being declared).
-- SCIL_Controlling_Tag
-- Present in N_SCIL_Dispatching_Call nodes. References the controlling
-- tag of a dispatching call. This is usually an N_Selected_Component
-- node (for a _tag component), but may be an N_Object_Declaration or
-- N_Parameter_Specification node in some cases (e.g., for a call to
-- a classwide streaming operation or a call to an instance of
-- Ada.Tags.Generic_Dispatching_Constructor).
-- SCIL_Tag_Value
-- Present in N_SCIL_Membership_Test nodes. Used to reference the tag
-- of the value that is being tested.
-- SCIL_Target_Prim
-- Present in N_SCIL_Dispatching_Call nodes. References the primitive
-- operation named (statically) in a dispatching call.
-- Scope
-- Present in defining identifiers, defining character literals, and
-- defining operator symbols (i.e. in all entities). The entities of a
-- scope all use this field to reference the corresponding scope entity.
-- See Einfo for further details.
-- Shift_Count_OK
-- A flag present in shift nodes to indicate that the shift count is
-- known to be in range, i.e. is in the range from zero to word length
-- minus one. If this flag is not set, then the shift count may be
-- outside this range, i.e. larger than the word length, and the code
-- must ensure that such shift counts give the appropriate result.
-- Source_Type
-- Used in an N_Validate_Unchecked_Conversion node to point to the
-- source type entity for the unchecked conversion instantiation
-- which gigi must do size validation for.
-- Split_PPC
-- When a Pre or Post aspect specification is processed, it is broken
-- into AND THEN sections. The leftmost section has Split_PPC set to
-- False, indicating that it is the original specification (e.g. for
-- posting errors). For other sections, Split_PPC is set to True.
-- This flag is set in both the N_Aspect_Specification node itself,
-- and in the pragma which is generated from this node.
-- Storage_Pool
-- Present in N_Allocator, N_Free_Statement, N_Simple_Return_Statement,
-- and N_Extended_Return_Statement nodes. References the entity for the
-- storage pool to be used for the allocate or free call or for the
-- allocation of the returned value from function. Empty indicates that
-- the global default pool is to be used. Note that in the case
-- of a return statement, this field is set only if the function returns
-- value of a type whose size is not known at compile time on the
-- secondary stack.
-- Suppress_Assignment_Checks
-- Used in generated N_Assignment_Statement nodes to suppress predicate
-- and range checks in cases where the generated code knows that the
-- value being assigned is in range and satisfies any predicate. Also
-- can be set in N_Object_Declaration nodes, to similarly suppress any
-- checks on the initializing value. In assignment statements it also
-- suppresses access checks in the generated code for out- and in-out
-- parameters in entry calls.
-- Suppress_Loop_Warnings
-- Used in N_Loop_Statement node to indicate that warnings within the
-- body of the loop should be suppressed. This is set when the range
-- of a FOR loop is known to be null, or is probably null (loop would
-- only execute if invalid values are present).
-- Target
-- Present in call and variable reference marker nodes. References the
-- entity of the original entity, operator, or subprogram being invoked,
-- or the original variable being read or written.
-- Target_Type
-- Used in an N_Validate_Unchecked_Conversion node to point to the target
-- type entity for the unchecked conversion instantiation which gigi must
-- do size validation for.
-- Then_Actions
-- This field is present in if expression nodes. During code expansion
-- we use the Insert_Actions procedure (in Exp_Util) to insert actions
-- at an appropriate place in the tree to get elaborated at the right
-- time. For if expressions, we have to be sure that the actions for
-- for the Then branch are only elaborated if the condition is True.
-- The Then_Actions field is used as a temporary parking place for
-- these actions. The final tree is always rewritten to eliminate the
-- need for this field, so in the tree passed to Gigi, this field is
-- always set to No_List.
-- TSS_Elist
-- Present in N_Freeze_Entity nodes. Holds an element list containing
-- entries for each TSS (type support subprogram) associated with the
-- frozen type. The elements of the list are the entities for the
-- subprograms (see package Exp_TSS for further details). Set to No_Elist
-- if there are no type support subprograms for the type or if the freeze
-- node is not for a type.
-- Uneval_Old_Accept
-- Present in N_Pragma nodes. Set True if Opt.Uneval_Old is set to 'A'
-- (accept) at the point where the pragma is encountered (including the
-- case of a pragma generated from an aspect specification). It is this
-- setting that is relevant, rather than the setting at the point where
-- a contract is finally analyzed after the delay till the freeze point.
-- Uneval_Old_Warn
-- Present in N_Pragma nodes. Set True if Opt.Uneval_Old is set to 'W'
-- (warn) at the point where the pragma is encountered (including the
-- case of a pragma generated from an aspect specification). It is this
-- setting that is relevant, rather than the setting at the point where
-- a contract is finally analyzed after the delay till the freeze point.
-- Unreferenced_In_Spec
-- Present in N_With_Clause nodes. Set if the with clause is on the
-- package or subprogram spec where the main unit is the corresponding
-- body, and is not referenced by the spec (it may still be referenced by
-- the body, so this flag is used to generate the proper message (see
-- Sem_Util.Check_Unused_Withs for details)
-- Uninitialized_Variable
-- Present in N_Formal_Private_Type_Definition and in N_Private_
-- Extension_Declarations. Indicates that a variable in a generic unit
-- whose type is a formal private or derived type is read without being
-- initialized. Used to warn if the corresponding actual type is not
-- a fully initialized type.
-- Used_Operations
-- Present in N_Use_Type_Clause nodes. Holds the list of operations that
-- are made potentially use-visible by the clause. Simplifies processing
-- on exit from the scope of the use_type_clause, in particular in the
-- case of Use_All_Type, when those operations several scopes.
-- Was_Attribute_Reference
-- Present in N_Subprogram_Body. Set to True if the original source is an
-- attribute reference which is an actual in a generic instantiation. The
-- instantiation prologue renames these attributes, and expansion later
-- converts them into subprogram bodies.
-- Was_Expression_Function
-- Present in N_Subprogram_Body. True if the original source had an
-- N_Expression_Function, which was converted to the N_Subprogram_Body
-- by Analyze_Expression_Function.
-- Was_Originally_Stub
-- This flag is set in the node for a proper body that replaces stub.
-- During the analysis procedure, stubs in some situations get rewritten
-- by the corresponding bodies, and we set this flag to remember that
-- this happened. Note that it is not good enough to rely on the use of
-- Original_Node here because of the case of nested instantiations where
-- the substituted node can be copied.
--------------------------------------------------
-- Note on Use of End_Label and End_Span Fields --
--------------------------------------------------
-- Several constructs have end lines:
-- Loop Statement end loop [loop_IDENTIFIER];
-- Package Specification end [[PARENT_UNIT_NAME .] IDENTIFIER]
-- Task Definition end [task_IDENTIFIER]
-- Protected Definition end [protected_IDENTIFIER]
-- Protected Body end [protected_IDENTIFIER]
-- Block Statement end [block_IDENTIFIER];
-- Subprogram Body end [DESIGNATOR];
-- Package Body end [[PARENT_UNIT_NAME .] IDENTIFIER];
-- Task Body end [task_IDENTIFIER];
-- Accept Statement end [entry_IDENTIFIER]];
-- Entry Body end [entry_IDENTIFIER];
-- If Statement end if;
-- Case Statement end case;
-- Record Definition end record;
-- Enumeration Definition );
-- The End_Label and End_Span fields are used to mark the locations of
-- these lines, and also keep track of the label in the case where a label
-- is present.
-- For the first group above, the End_Label field of the corresponding node
-- is used to point to the label identifier. In the case where there is no
-- label in the source, the parser supplies a dummy identifier (with
-- Comes_From_Source set to False), and the Sloc of this dummy identifier
-- marks the location of the token following the END token.
-- For the second group, the use of End_Label is similar, but the End_Label
-- is found in the N_Handled_Sequence_Of_Statements node. This is done
-- simply because in some cases there is no room in the parent node.
-- For the third group, there is never any label, and instead of using
-- End_Label, we use the End_Span field which gives the location of the
-- token following END, relative to the starting Sloc of the construct,
-- i.e. add Sloc (Node) + End_Span (Node) to get the Sloc of the IF or CASE
-- following the End_Label.
-- The record definition case is handled specially, we treat it as though
-- it required an optional label which is never present, and so the parser
-- always builds a dummy identifier with Comes From Source set False. The
-- reason we do this, rather than using End_Span in this case, is that we
-- want to generate a cross-ref entry for the end of a record, since it
-- represents a scope for name declaration purposes.
-- The enumeration definition case is handled in an exactly similar manner,
-- building a dummy identifier to get a cross-reference.
-- Note: the reason we store the difference as a Uint, instead of storing
-- the Source_Ptr value directly, is that Source_Ptr values cannot be
-- distinguished from other types of values, and we count on all general
-- use fields being self describing. To make things easier for clients,
-- note that we provide function End_Location, and procedure
-- Set_End_Location to allow access to the logical value (which is the
-- Source_Ptr value for the end token).
---------------------
-- Syntactic Nodes --
---------------------
---------------------
-- 2.3 Identifier --
---------------------
-- IDENTIFIER ::= IDENTIFIER_LETTER {[UNDERLINE] LETTER_OR_DIGIT}
-- LETTER_OR_DIGIT ::= IDENTIFIER_LETTER | DIGIT
-- An IDENTIFIER shall not be a reserved word
-- In the Ada grammar identifiers are the bottom level tokens which have
-- very few semantics. Actual program identifiers are direct names. If
-- we were being 100% honest with the grammar, then we would have a node
-- called N_Direct_Name which would point to an identifier. However,
-- that's too many extra nodes, so we just use the N_Identifier node
-- directly as a direct name, and it contains the expression fields and
-- Entity field that correspond to its use as a direct name. In those
-- few cases where identifiers appear in contexts where they are not
-- direct names (pragmas, pragma argument associations, attribute
-- references and attribute definition clauses), the Chars field of the
-- node contains the Name_Id for the identifier name.
-- Note: in GNAT, a reserved word can be treated as an identifier in two
-- cases. First, an incorrect use of a reserved word as an identifier is
-- diagnosed and then treated as a normal identifier. Second, an
-- attribute designator of the form of a reserved word (access, delta,
-- digits, range) is treated as an identifier.
-- Note: The set of letters that is permitted in an identifier depends
-- on the character set in use. See package Csets for full details.
-- N_Identifier
-- Sloc points to identifier
-- Chars contains the Name_Id for the identifier
-- Entity
-- Associated_Node
-- Original_Discriminant
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Has_Private_View (set in generic units)
-- Redundant_Use
-- Atomic_Sync_Required
-- plus fields for expression
--------------------------
-- 2.4 Numeric Literal --
--------------------------
-- NUMERIC_LITERAL ::= DECIMAL_LITERAL | BASED_LITERAL
----------------------------
-- 2.4.1 Decimal Literal --
----------------------------
-- DECIMAL_LITERAL ::= NUMERAL [.NUMERAL] [EXPONENT]
-- NUMERAL ::= DIGIT {[UNDERLINE] DIGIT}
-- EXPONENT ::= E [+] NUMERAL | E - NUMERAL
-- Decimal literals appear in the tree as either integer literal nodes
-- or real literal nodes, depending on whether a period is present.
-- Note: literal nodes appear as a result of direct use of literals
-- in the source program, and also as the result of evaluating
-- expressions at compile time. In the latter case, it is possible
-- to construct real literals that have no syntactic representation
-- using the standard literal format. Such literals are listed by
-- Sprint using the notation [numerator / denominator].
-- Note: the value of an integer literal node created by the front end
-- is never outside the range of values of the base type. However, it
-- can be the case that the created value is outside the range of the
-- particular subtype. This happens in the case of integer overflows
-- with checks suppressed.
-- N_Integer_Literal
-- Sloc points to literal
-- Original_Entity If not Empty, holds Named_Number that
-- has been constant-folded into its literal value.
-- Intval contains integer value of literal
-- Print_In_Hex
-- plus fields for expression
-- N_Real_Literal
-- Sloc points to literal
-- Original_Entity If not Empty, holds Named_Number that
-- has been constant-folded into its literal value.
-- Realval contains real value of literal
-- Corresponding_Integer_Value
-- Is_Machine_Number
-- plus fields for expression
--------------------------
-- 2.4.2 Based Literal --
--------------------------
-- BASED_LITERAL ::=
-- BASE # BASED_NUMERAL [.BASED_NUMERAL] # [EXPONENT]
-- BASE ::= NUMERAL
-- BASED_NUMERAL ::=
-- EXTENDED_DIGIT {[UNDERLINE] EXTENDED_DIGIT}
-- EXTENDED_DIGIT ::= DIGIT | A | B | C | D | E | F
-- Based literals appear in the tree as either integer literal nodes
-- or real literal nodes, depending on whether a period is present.
----------------------------
-- 2.5 Character Literal --
----------------------------
-- CHARACTER_LITERAL ::= ' GRAPHIC_CHARACTER '
-- N_Character_Literal
-- Sloc points to literal
-- Chars contains the Name_Id for the identifier
-- Char_Literal_Value contains the literal value
-- Entity
-- Associated_Node
-- Has_Private_View (set in generic units)
-- plus fields for expression
-- Note: the Entity field will be missing (set to Empty) for character
-- literals whose type is Standard.Wide_Character or Standard.Character
-- or a type derived from one of these two. In this case the character
-- literal stands for its own coding. The reason we take this irregular
-- short cut is to avoid the need to build lots of junk defining
-- character literal nodes.
-------------------------
-- 2.6 String Literal --
-------------------------
-- STRING LITERAL ::= "{STRING_ELEMENT}"
-- A STRING_ELEMENT is either a pair of quotation marks ("), or a
-- single GRAPHIC_CHARACTER other than a quotation mark.
--
-- Is_Folded_In_Parser is True if the parser created this literal by
-- folding a sequence of "&" operators. For example, if the source code
-- says "aaa" & "bbb" & "ccc", and this produces "aaabbbccc", the flag
-- is set. This flag is needed because the parser doesn't know about
-- visibility, so the folded result might be wrong, and semantic
-- analysis needs to check for that.
-- N_String_Literal
-- Sloc points to literal
-- Strval contains Id of string value
-- Has_Wide_Character
-- Has_Wide_Wide_Character
-- Is_Folded_In_Parser
-- plus fields for expression
------------------
-- 2.7 Comment --
------------------
-- A COMMENT starts with two adjacent hyphens and extends up to the
-- end of the line. A COMMENT may appear on any line of a program.
-- Comments are skipped by the scanner and do not appear in the tree.
-- It is possible to reconstruct the position of comments with respect
-- to the elements of the tree by using the source position (Sloc)
-- pointers that appear in every tree node.
-----------------
-- 2.8 Pragma --
-----------------
-- PRAGMA ::= pragma IDENTIFIER
-- [(PRAGMA_ARGUMENT_ASSOCIATION {, PRAGMA_ARGUMENT_ASSOCIATION})];
-- Note that a pragma may appear in the tree anywhere a declaration
-- or a statement may appear, as well as in some other situations
-- which are explicitly documented.
-- N_Pragma
-- Sloc points to PRAGMA
-- Next_Pragma
-- Pragma_Argument_Associations (set to No_List if none)
-- Corresponding_Aspect (set to Empty if not present)
-- Pragma_Identifier
-- Next_Rep_Item
-- Is_Generic_Contract_Pragma
-- Is_Checked_Ghost_Pragma
-- Is_Inherited_Pragma
-- Is_Analyzed_Pragma
-- Class_Present set if from Aspect with 'Class
-- Uneval_Old_Accept
-- Is_Ignored_Ghost_Pragma
-- Is_Ignored
-- Is_Checked
-- From_Aspect_Specification
-- Is_Delayed_Aspect
-- Is_Disabled
-- Import_Interface_Present
-- Split_PPC set if corresponding aspect had Split_PPC set
-- Uneval_Old_Warn
-- Note: we should have a section on what pragmas are passed on to
-- the back end to be processed. This section should note that pragma
-- Psect_Object is always converted to Common_Object, but there are
-- undoubtedly many other similar notes required ???
-- Note: utility functions Pragma_Name_Unmapped and Pragma_Name may be
-- applied to pragma nodes to obtain the Chars or its mapped version.
-- Note: if From_Aspect_Specification is set, then Sloc points to the
-- aspect name, as does the Pragma_Identifier. In this case if the
-- pragma has a local name argument (such as pragma Inline), it is
-- resolved to point to the specific entity affected by the pragma.
--------------------------------------
-- 2.8 Pragma Argument Association --
--------------------------------------
-- PRAGMA_ARGUMENT_ASSOCIATION ::=
-- [pragma_argument_IDENTIFIER =>] NAME
-- | [pragma_argument_IDENTIFIER =>] EXPRESSION
-- In Ada 2012, there are two more possibilities:
-- PRAGMA_ARGUMENT_ASSOCIATION ::=
-- [pragma_argument_ASPECT_MARK =>] NAME
-- | [pragma_argument_ASPECT_MARK =>] EXPRESSION
-- where the interesting allowed cases (which do not fit the syntax of
-- the first alternative above) are
-- ASPECT_MARK => Pre'Class |
-- Post'Class |
-- Type_Invariant'Class |
-- Invariant'Class
-- We allow this special usage in all Ada modes, but it would be a
-- pain to allow these aspects to pervade the pragma syntax, and the
-- representation of pragma nodes internally. So what we do is to
-- replace these ASPECT_MARK forms with identifiers whose name is one
-- of the special internal names _Pre, _Post, or _Type_Invariant.
-- We do a similar replacement of these Aspect_Mark forms in the
-- Expression of a pragma argument association for the cases of
-- the first arguments of any Check pragmas and Check_Policy pragmas
-- N_Pragma_Argument_Association
-- Sloc points to first token in association
-- Chars (set to No_Name if no pragma argument identifier)
-- Expression_Copy
-- Expression
------------------------
-- 2.9 Reserved Word --
------------------------
-- Reserved words are parsed by the scanner, and returned as the
-- corresponding token types (e.g. PACKAGE is returned as Tok_Package)
----------------------------
-- 3.1 Basic Declaration --
----------------------------
-- BASIC_DECLARATION ::=
-- TYPE_DECLARATION | SUBTYPE_DECLARATION
-- | OBJECT_DECLARATION | NUMBER_DECLARATION
-- | SUBPROGRAM_DECLARATION | ABSTRACT_SUBPROGRAM_DECLARATION
-- | PACKAGE_DECLARATION | RENAMING_DECLARATION
-- | EXCEPTION_DECLARATION | GENERIC_DECLARATION
-- | GENERIC_INSTANTIATION
-- Basic declaration also includes IMPLICIT_LABEL_DECLARATION
-- see further description in section on semantic nodes.
-- Also, in the tree that is constructed, a pragma may appear
-- anywhere that a declaration may appear.
------------------------------
-- 3.1 Defining Identifier --
------------------------------
-- DEFINING_IDENTIFIER ::= IDENTIFIER
-- A defining identifier is an entity, which has additional fields
-- depending on the setting of the Ekind field. These additional
-- fields are defined (and access subprograms declared) in package
-- Einfo.
-- Note: N_Defining_Identifier is an extended node whose fields are
-- deliberately laid out to match the layout of fields in an ordinary
-- N_Identifier node allowing for easy alteration of an identifier
-- node into a defining identifier node. For details, see procedure
-- Sinfo.CN.Change_Identifier_To_Defining_Identifier.
-- N_Defining_Identifier
-- Sloc points to identifier
-- Chars contains the Name_Id for the identifier
-- Next_Entity
-- Scope
-- Etype
-----------------------------
-- 3.2.1 Type Declaration --
-----------------------------
-- TYPE_DECLARATION ::=
-- FULL_TYPE_DECLARATION
-- | INCOMPLETE_TYPE_DECLARATION
-- | PRIVATE_TYPE_DECLARATION
-- | PRIVATE_EXTENSION_DECLARATION
----------------------------------
-- 3.2.1 Full Type Declaration --
----------------------------------
-- FULL_TYPE_DECLARATION ::=
-- type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART]
-- is TYPE_DEFINITION
-- [ASPECT_SPECIFICATIONS];
-- | TASK_TYPE_DECLARATION
-- | PROTECTED_TYPE_DECLARATION
-- The full type declaration node is used only for the first case. The
-- second case (concurrent type declaration), is represented directly
-- by a task type declaration or a protected type declaration.
-- N_Full_Type_Declaration
-- Sloc points to TYPE
-- Defining_Identifier
-- Incomplete_View
-- Discriminant_Specifications (set to No_List if none)
-- Type_Definition
-- Discr_Check_Funcs_Built
----------------------------
-- 3.2.1 Type Definition --
----------------------------
-- TYPE_DEFINITION ::=
-- ENUMERATION_TYPE_DEFINITION | INTEGER_TYPE_DEFINITION
-- | REAL_TYPE_DEFINITION | ARRAY_TYPE_DEFINITION
-- | RECORD_TYPE_DEFINITION | ACCESS_TYPE_DEFINITION
-- | DERIVED_TYPE_DEFINITION | INTERFACE_TYPE_DEFINITION
--------------------------------
-- 3.2.2 Subtype Declaration --
--------------------------------
-- SUBTYPE_DECLARATION ::=
-- subtype DEFINING_IDENTIFIER is [NULL_EXCLUSION] SUBTYPE_INDICATION
-- [ASPECT_SPECIFICATIONS];
-- The subtype indication field is set to Empty for subtypes
-- declared in package Standard (Positive, Natural).
-- N_Subtype_Declaration
-- Sloc points to SUBTYPE
-- Defining_Identifier
-- Null_Exclusion_Present
-- Subtype_Indication
-- Generic_Parent_Type (set for an actual derived type).
-- Exception_Junk
-------------------------------
-- 3.2.2 Subtype Indication --
-------------------------------
-- SUBTYPE_INDICATION ::= SUBTYPE_MARK [CONSTRAINT]
-- Note: if no constraint is present, the subtype indication appears
-- directly in the tree as a subtype mark. The N_Subtype_Indication
-- node is used only if a constraint is present.
-- Note: [For Ada 2005 (AI-231)]: Because Ada 2005 extends this rule
-- with the null-exclusion part (see AI-231), we had to introduce a new
-- attribute in all the parents of subtype_indication nodes to indicate
-- if the null-exclusion is present.
-- Note: the reason that this node has expression fields is that a
-- subtype indication can appear as an operand of a membership test.
-- N_Subtype_Indication
-- Sloc points to first token of subtype mark
-- Subtype_Mark
-- Constraint
-- Etype
-- Must_Not_Freeze
-- Note: Depending on context, the Etype is either the entity of the
-- Subtype_Mark field, or it is an itype constructed to reify the
-- subtype indication. In particular, such itypes are created for a
-- subtype indication that appears in an array type declaration. This
-- simplifies constraint checking in indexed components.
-- For subtype indications that appear in scalar type and subtype
-- declarations, the Etype is the entity of the subtype mark.
-------------------------
-- 3.2.2 Subtype Mark --
-------------------------
-- SUBTYPE_MARK ::= subtype_NAME
-----------------------
-- 3.2.2 Constraint --
-----------------------
-- CONSTRAINT ::= SCALAR_CONSTRAINT | COMPOSITE_CONSTRAINT
------------------------------
-- 3.2.2 Scalar Constraint --
------------------------------
-- SCALAR_CONSTRAINT ::=
-- RANGE_CONSTRAINT | DIGITS_CONSTRAINT | DELTA_CONSTRAINT
---------------------------------
-- 3.2.2 Composite Constraint --
---------------------------------
-- COMPOSITE_CONSTRAINT ::=
-- INDEX_CONSTRAINT | DISCRIMINANT_CONSTRAINT
-------------------------------
-- 3.3.1 Object Declaration --
-------------------------------
-- OBJECT_DECLARATION ::=
-- DEFINING_IDENTIFIER_LIST : [aliased] [constant]
-- [NULL_EXCLUSION] SUBTYPE_INDICATION [:= EXPRESSION]
-- [ASPECT_SPECIFICATIONS];
-- | DEFINING_IDENTIFIER_LIST : [aliased] [constant]
-- ACCESS_DEFINITION [:= EXPRESSION]
-- [ASPECT_SPECIFICATIONS];
-- | DEFINING_IDENTIFIER_LIST : [aliased] [constant]
-- ARRAY_TYPE_DEFINITION [:= EXPRESSION]
-- [ASPECT_SPECIFICATIONS];
-- | SINGLE_TASK_DECLARATION
-- | SINGLE_PROTECTED_DECLARATION
-- Note: aliased is not permitted in Ada 83 mode
-- The N_Object_Declaration node is only for the first three cases.
-- Single task declaration is handled by P_Task (9.1)
-- Single protected declaration is handled by P_protected (9.5)
-- Although the syntax allows multiple identifiers in the list, the
-- semantics is as though successive declarations were given with
-- identical type definition and expression components. To simplify
-- semantic processing, the parser represents a multiple declaration
-- case as a sequence of single declarations, using the More_Ids and
-- Prev_Ids flags to preserve the original source form as described
-- in the section on "Handling of Defining Identifier Lists".
-- The flag Has_Init_Expression is set if an initializing expression
-- is present. Normally it is set if and only if Expression contains
-- a non-empty value, but there is an exception to this. When the
-- initializing expression is an aggregate which requires explicit
-- assignments, the Expression field gets set to Empty, but this flag
-- is still set, so we don't forget we had an initializing expression.
-- Note: if a range check is required for the initialization
-- expression then the Do_Range_Check flag is set in the Expression,
-- with the check being done against the type given by the object
-- definition, which is also the Etype of the defining identifier.
-- Note: the contents of the Expression field must be ignored (i.e.
-- treated as though it were Empty) if No_Initialization is set True.
-- Note: the back end places some restrictions on the form of the
-- Expression field. If the object being declared is Atomic, then
-- the Expression may not have the form of an aggregate (since this
-- might cause the back end to generate separate assignments). In this
-- case the front end must generate an extra temporary and initialize
-- this temporary as required (the temporary itself is not atomic).
-- Note: there is no node kind for object definition. Instead, the
-- corresponding field holds a subtype indication, an array type
-- definition, or (Ada 2005, AI-406) an access definition.
-- N_Object_Declaration
-- Sloc points to first identifier
-- Defining_Identifier
-- Aliased_Present
-- Constant_Present set if CONSTANT appears
-- Null_Exclusion_Present
-- Object_Definition subtype indic./array type def./access def.
-- Expression (set to Empty if not present)
-- Handler_List_Entry
-- Corresponding_Generic_Association
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
-- No_Initialization
-- Assignment_OK
-- Exception_Junk
-- Is_Subprogram_Descriptor
-- Has_Init_Expression
-- Suppress_Assignment_Checks
-------------------------------------
-- 3.3.1 Defining Identifier List --
-------------------------------------
-- DEFINING_IDENTIFIER_LIST ::=
-- DEFINING_IDENTIFIER {, DEFINING_IDENTIFIER}
-------------------------------
-- 3.3.2 Number Declaration --
-------------------------------
-- NUMBER_DECLARATION ::=
-- DEFINING_IDENTIFIER_LIST : constant := static_EXPRESSION;
-- Although the syntax allows multiple identifiers in the list, the
-- semantics is as though successive declarations were given with
-- identical expressions. To simplify semantic processing, the parser
-- represents a multiple declaration case as a sequence of single
-- declarations, using the More_Ids and Prev_Ids flags to preserve
-- the original source form as described in the section on "Handling
-- of Defining Identifier Lists".
-- N_Number_Declaration
-- Sloc points to first identifier
-- Defining_Identifier
-- Expression
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
----------------------------------
-- 3.4 Derived Type Definition --
----------------------------------
-- DERIVED_TYPE_DEFINITION ::=
-- [abstract] [limited] new [NULL_EXCLUSION] parent_SUBTYPE_INDICATION
-- [[and INTERFACE_LIST] RECORD_EXTENSION_PART]
-- Note: ABSTRACT, LIMITED, and record extension part are not permitted
-- in Ada 83 mode.
-- Note: a record extension part is required if ABSTRACT is present
-- N_Derived_Type_Definition
-- Sloc points to NEW
-- Abstract_Present
-- Null_Exclusion_Present (set to False if not present)
-- Subtype_Indication
-- Record_Extension_Part (set to Empty if not present)
-- Limited_Present
-- Task_Present set in task interfaces
-- Protected_Present set in protected interfaces
-- Synchronized_Present set in interfaces
-- Interface_List (set to No_List if none)
-- Interface_Present set in abstract interfaces
-- Note: Task_Present, Protected_Present, Synchronized_Present,
-- Interface_List, and Interface_Present are used for abstract
-- interfaces (see comments for INTERFACE_TYPE_DEFINITION).
---------------------------
-- 3.5 Range Constraint --
---------------------------
-- RANGE_CONSTRAINT ::= range RANGE
-- N_Range_Constraint
-- Sloc points to RANGE
-- Range_Expression
----------------
-- 3.5 Range --
----------------
-- RANGE ::=
-- RANGE_ATTRIBUTE_REFERENCE
-- | SIMPLE_EXPRESSION .. SIMPLE_EXPRESSION
-- Note: the case of a range given as a range attribute reference
-- appears directly in the tree as an attribute reference.
-- Note: the field name for a reference to a range is Range_Expression
-- rather than Range, because range is a reserved keyword in Ada.
-- Note: the reason that this node has expression fields is that a
-- range can appear as an operand of a membership test. The Etype
-- field is the type of the range (we do NOT construct an implicit
-- subtype to represent the range exactly).
-- N_Range
-- Sloc points to ..
-- Low_Bound
-- High_Bound
-- Includes_Infinities
-- plus fields for expression
-- Note: if the range appears in a context, such as a subtype
-- declaration, where range checks are required on one or both of
-- the expression fields, then type conversion nodes are inserted
-- to represent the required checks.
----------------------------------------
-- 3.5.1 Enumeration Type Definition --
----------------------------------------
-- ENUMERATION_TYPE_DEFINITION ::=
-- (ENUMERATION_LITERAL_SPECIFICATION
-- {, ENUMERATION_LITERAL_SPECIFICATION})
-- Note: the Literals field in the node described below is null for
-- the case of the standard types CHARACTER and WIDE_CHARACTER, for
-- which special processing handles these types as special cases.
-- N_Enumeration_Type_Definition
-- Sloc points to left parenthesis
-- Literals (Empty for CHARACTER or WIDE_CHARACTER)
-- End_Label (set to Empty if internally generated record)
----------------------------------------------
-- 3.5.1 Enumeration Literal Specification --
----------------------------------------------
-- ENUMERATION_LITERAL_SPECIFICATION ::=
-- DEFINING_IDENTIFIER | DEFINING_CHARACTER_LITERAL
---------------------------------------
-- 3.5.1 Defining Character Literal --
---------------------------------------
-- DEFINING_CHARACTER_LITERAL ::= CHARACTER_LITERAL
-- A defining character literal is an entity, which has additional
-- fields depending on the setting of the Ekind field. These
-- additional fields are defined (and access subprograms declared)
-- in package Einfo.
-- Note: N_Defining_Character_Literal is an extended node whose fields
-- are deliberately laid out to match layout of fields in an ordinary
-- N_Character_Literal node, allowing for easy alteration of a character
-- literal node into a defining character literal node. For details, see
-- Sinfo.CN.Change_Character_Literal_To_Defining_Character_Literal.
-- N_Defining_Character_Literal
-- Sloc points to literal
-- Chars contains the Name_Id for the identifier
-- Next_Entity
-- Scope
-- Etype
------------------------------------
-- 3.5.4 Integer Type Definition --
------------------------------------
-- Note: there is an error in this rule in the latest version of the
-- grammar, so we have retained the old rule pending clarification.
-- INTEGER_TYPE_DEFINITION ::=
-- SIGNED_INTEGER_TYPE_DEFINITION
-- | MODULAR_TYPE_DEFINITION
-------------------------------------------
-- 3.5.4 Signed Integer Type Definition --
-------------------------------------------
-- SIGNED_INTEGER_TYPE_DEFINITION ::=
-- range static_SIMPLE_EXPRESSION .. static_SIMPLE_EXPRESSION
-- Note: the Low_Bound and High_Bound fields are set to Empty
-- for integer types defined in package Standard.
-- N_Signed_Integer_Type_Definition
-- Sloc points to RANGE
-- Low_Bound
-- High_Bound
------------------------------------
-- 3.5.4 Modular Type Definition --
------------------------------------
-- MODULAR_TYPE_DEFINITION ::= mod static_EXPRESSION
-- N_Modular_Type_Definition
-- Sloc points to MOD
-- Expression
---------------------------------
-- 3.5.6 Real Type Definition --
---------------------------------
-- REAL_TYPE_DEFINITION ::=
-- FLOATING_POINT_DEFINITION | FIXED_POINT_DEFINITION
--------------------------------------
-- 3.5.7 Floating Point Definition --
--------------------------------------
-- FLOATING_POINT_DEFINITION ::=
-- digits static_SIMPLE_EXPRESSION [REAL_RANGE_SPECIFICATION]
-- Note: The Digits_Expression and Real_Range_Specifications fields
-- are set to Empty for floating-point types declared in Standard.
-- N_Floating_Point_Definition
-- Sloc points to DIGITS
-- Digits_Expression
-- Real_Range_Specification (set to Empty if not present)
-------------------------------------
-- 3.5.7 Real Range Specification --
-------------------------------------
-- REAL_RANGE_SPECIFICATION ::=
-- range static_SIMPLE_EXPRESSION .. static_SIMPLE_EXPRESSION
-- N_Real_Range_Specification
-- Sloc points to RANGE
-- Low_Bound
-- High_Bound
-----------------------------------
-- 3.5.9 Fixed Point Definition --
-----------------------------------
-- FIXED_POINT_DEFINITION ::=
-- ORDINARY_FIXED_POINT_DEFINITION | DECIMAL_FIXED_POINT_DEFINITION
--------------------------------------------
-- 3.5.9 Ordinary Fixed Point Definition --
--------------------------------------------
-- ORDINARY_FIXED_POINT_DEFINITION ::=
-- delta static_EXPRESSION REAL_RANGE_SPECIFICATION
-- Note: In Ada 83, the EXPRESSION must be a SIMPLE_EXPRESSION
-- N_Ordinary_Fixed_Point_Definition
-- Sloc points to DELTA
-- Delta_Expression
-- Real_Range_Specification
-------------------------------------------
-- 3.5.9 Decimal Fixed Point Definition --
-------------------------------------------
-- DECIMAL_FIXED_POINT_DEFINITION ::=
-- delta static_EXPRESSION
-- digits static_EXPRESSION [REAL_RANGE_SPECIFICATION]
-- Note: decimal types are not permitted in Ada 83 mode
-- N_Decimal_Fixed_Point_Definition
-- Sloc points to DELTA
-- Delta_Expression
-- Digits_Expression
-- Real_Range_Specification (set to Empty if not present)
------------------------------
-- 3.5.9 Digits Constraint --
------------------------------
-- DIGITS_CONSTRAINT ::=
-- digits static_EXPRESSION [RANGE_CONSTRAINT]
-- Note: in Ada 83, the EXPRESSION must be a SIMPLE_EXPRESSION
-- Note: in Ada 95, reduced accuracy subtypes are obsolescent
-- N_Digits_Constraint
-- Sloc points to DIGITS
-- Digits_Expression
-- Range_Constraint (set to Empty if not present)
--------------------------------
-- 3.6 Array Type Definition --
--------------------------------
-- ARRAY_TYPE_DEFINITION ::=
-- UNCONSTRAINED_ARRAY_DEFINITION | CONSTRAINED_ARRAY_DEFINITION
-----------------------------------------
-- 3.6 Unconstrained Array Definition --
-----------------------------------------
-- UNCONSTRAINED_ARRAY_DEFINITION ::=
-- array (INDEX_SUBTYPE_DEFINITION {, INDEX_SUBTYPE_DEFINITION}) of
-- COMPONENT_DEFINITION
-- Note: dimensionality of array is indicated by number of entries in
-- the Subtype_Marks list, which has one entry for each dimension.
-- N_Unconstrained_Array_Definition
-- Sloc points to ARRAY
-- Subtype_Marks
-- Component_Definition
-----------------------------------
-- 3.6 Index Subtype Definition --
-----------------------------------
-- INDEX_SUBTYPE_DEFINITION ::= SUBTYPE_MARK range <>
-- There is no explicit node in the tree for an index subtype
-- definition since the N_Unconstrained_Array_Definition node
-- incorporates the type marks which appear in this context.
---------------------------------------
-- 3.6 Constrained Array Definition --
---------------------------------------
-- CONSTRAINED_ARRAY_DEFINITION ::=
-- array (DISCRETE_SUBTYPE_DEFINITION
-- {, DISCRETE_SUBTYPE_DEFINITION})
-- of COMPONENT_DEFINITION
-- Note: dimensionality of array is indicated by number of entries
-- in the Discrete_Subtype_Definitions list, which has one entry
-- for each dimension.
-- N_Constrained_Array_Definition
-- Sloc points to ARRAY
-- Discrete_Subtype_Definitions
-- Component_Definition
-- Note: although the language allows the full syntax for discrete
-- subtype definitions (i.e. a discrete subtype indication or a range),
-- in the generated tree, we always rewrite these as N_Range nodes.
--------------------------------------
-- 3.6 Discrete Subtype Definition --
--------------------------------------
-- DISCRETE_SUBTYPE_DEFINITION ::=
-- discrete_SUBTYPE_INDICATION | RANGE
-------------------------------
-- 3.6 Component Definition --
-------------------------------
-- COMPONENT_DEFINITION ::=
-- [aliased] [NULL_EXCLUSION] SUBTYPE_INDICATION | ACCESS_DEFINITION
-- Note: although the syntax does not permit a component definition to
-- be an anonymous array (and the parser will diagnose such an attempt
-- with an appropriate message), it is possible for anonymous arrays
-- to appear as component definitions. The semantics and back end handle
-- this case properly, and the expander in fact generates such cases.
-- Access_Definition is an optional field that gives support to
-- Ada 2005 (AI-230). The parser generates nodes that have either the
-- Subtype_Indication field or else the Access_Definition field.
-- N_Component_Definition
-- Sloc points to ALIASED, ACCESS, or to first token of subtype mark
-- Aliased_Present
-- Null_Exclusion_Present
-- Subtype_Indication (set to Empty if not present)
-- Access_Definition (set to Empty if not present)
-----------------------------
-- 3.6.1 Index Constraint --
-----------------------------
-- INDEX_CONSTRAINT ::= (DISCRETE_RANGE {, DISCRETE_RANGE})
-- It is not in general possible to distinguish between discriminant
-- constraints and index constraints at parse time, since a simple
-- name could be either the subtype mark of a discrete range, or an
-- expression in a discriminant association with no name. Either
-- entry appears simply as the name, and the semantic parse must
-- distinguish between the two cases. Thus we use a common tree
-- node format for both of these constraint types.
-- See Discriminant_Constraint for format of node
---------------------------
-- 3.6.1 Discrete Range --
---------------------------
-- DISCRETE_RANGE ::= discrete_SUBTYPE_INDICATION | RANGE
----------------------------
-- 3.7 Discriminant Part --
----------------------------
-- DISCRIMINANT_PART ::=
-- UNKNOWN_DISCRIMINANT_PART | KNOWN_DISCRIMINANT_PART
------------------------------------
-- 3.7 Unknown Discriminant Part --
------------------------------------
-- UNKNOWN_DISCRIMINANT_PART ::= (<>)
-- Note: unknown discriminant parts are not permitted in Ada 83 mode
-- There is no explicit node in the tree for an unknown discriminant
-- part. Instead the Unknown_Discriminants_Present flag is set in the
-- parent node.
----------------------------------
-- 3.7 Known Discriminant Part --
----------------------------------
-- KNOWN_DISCRIMINANT_PART ::=
-- (DISCRIMINANT_SPECIFICATION {; DISCRIMINANT_SPECIFICATION})
-------------------------------------
-- 3.7 Discriminant Specification --
-------------------------------------
-- DISCRIMINANT_SPECIFICATION ::=
-- DEFINING_IDENTIFIER_LIST : [NULL_EXCLUSION] SUBTYPE_MARK
-- [:= DEFAULT_EXPRESSION]
-- | DEFINING_IDENTIFIER_LIST : ACCESS_DEFINITION
-- [:= DEFAULT_EXPRESSION]
-- Although the syntax allows multiple identifiers in the list, the
-- semantics is as though successive specifications were given with
-- identical type definition and expression components. To simplify
-- semantic processing, the parser represents a multiple declaration
-- case as a sequence of single specifications, using the More_Ids and
-- Prev_Ids flags to preserve the original source form as described
-- in the section on "Handling of Defining Identifier Lists".
-- N_Discriminant_Specification
-- Sloc points to first identifier
-- Defining_Identifier
-- Null_Exclusion_Present
-- Discriminant_Type subtype mark or access parameter definition
-- Expression (set to Empty if no default expression)
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
-----------------------------
-- 3.7 Default Expression --
-----------------------------
-- DEFAULT_EXPRESSION ::= EXPRESSION
------------------------------------
-- 3.7.1 Discriminant Constraint --
------------------------------------
-- DISCRIMINANT_CONSTRAINT ::=
-- (DISCRIMINANT_ASSOCIATION {, DISCRIMINANT_ASSOCIATION})
-- It is not in general possible to distinguish between discriminant
-- constraints and index constraints at parse time, since a simple
-- name could be either the subtype mark of a discrete range, or an
-- expression in a discriminant association with no name. Either
-- entry appears simply as the name, and the semantic parse must
-- distinguish between the two cases. Thus we use a common tree
-- node format for both of these constraint types.
-- N_Index_Or_Discriminant_Constraint
-- Sloc points to left paren
-- Constraints points to list of discrete ranges or
-- discriminant associations
-------------------------------------
-- 3.7.1 Discriminant Association --
-------------------------------------
-- DISCRIMINANT_ASSOCIATION ::=
-- [discriminant_SELECTOR_NAME
-- {| discriminant_SELECTOR_NAME} =>] EXPRESSION
-- Note: a discriminant association that has no selector name list
-- appears directly as an expression in the tree.
-- N_Discriminant_Association
-- Sloc points to first token of discriminant association
-- Selector_Names (always non-empty, since if no selector
-- names are present, this node is not used, see comment above)
-- Expression
---------------------------------
-- 3.8 Record Type Definition --
---------------------------------
-- RECORD_TYPE_DEFINITION ::=
-- [[abstract] tagged] [limited] RECORD_DEFINITION
-- Note: ABSTRACT, TAGGED, LIMITED are not permitted in Ada 83 mode
-- There is no explicit node in the tree for a record type definition.
-- Instead the flags for Tagged_Present and Limited_Present appear in
-- the N_Record_Definition node for a record definition appearing in
-- the context of a record type definition.
----------------------------
-- 3.8 Record Definition --
----------------------------
-- RECORD_DEFINITION ::=
-- record
-- COMPONENT_LIST
-- end record
-- | null record
-- Note: the Abstract_Present, Tagged_Present, and Limited_Present
-- flags appear only for a record definition appearing in a record
-- type definition.
-- Note: the NULL RECORD case is not permitted in Ada 83
-- N_Record_Definition
-- Sloc points to RECORD or NULL
-- End_Label (set to Empty if internally generated record)
-- Abstract_Present
-- Tagged_Present
-- Limited_Present
-- Component_List empty in null record case
-- Null_Present set in null record case
-- Task_Present set in task interfaces
-- Protected_Present set in protected interfaces
-- Synchronized_Present set in interfaces
-- Interface_Present set in abstract interfaces
-- Interface_List (set to No_List if none)
-- Note: Task_Present, Protected_Present, Synchronized _Present,
-- Interface_List and Interface_Present are used for abstract
-- interfaces (see comments for INTERFACE_TYPE_DEFINITION).
-------------------------
-- 3.8 Component List --
-------------------------
-- COMPONENT_LIST ::=
-- COMPONENT_ITEM {COMPONENT_ITEM}
-- | {COMPONENT_ITEM} VARIANT_PART
-- | null;
-- N_Component_List
-- Sloc points to first token of component list
-- Component_Items
-- Variant_Part (set to Empty if no variant part)
-- Null_Present
-------------------------
-- 3.8 Component Item --
-------------------------
-- COMPONENT_ITEM ::= COMPONENT_DECLARATION | REPRESENTATION_CLAUSE
-- Note: A component item can also be a pragma, and in the tree
-- that is obtained after semantic processing, a component item
-- can be an N_Null node resulting from a non-recognized pragma.
--------------------------------
-- 3.8 Component Declaration --
--------------------------------
-- COMPONENT_DECLARATION ::=
-- DEFINING_IDENTIFIER_LIST : COMPONENT_DEFINITION
-- [:= DEFAULT_EXPRESSION]
-- [ASPECT_SPECIFICATIONS];
-- Note: although the syntax does not permit a component definition to
-- be an anonymous array (and the parser will diagnose such an attempt
-- with an appropriate message), it is possible for anonymous arrays
-- to appear as component definitions. The semantics and back end handle
-- this case properly, and the expander in fact generates such cases.
-- Although the syntax allows multiple identifiers in the list, the
-- semantics is as though successive declarations were given with the
-- same component definition and expression components. To simplify
-- semantic processing, the parser represents a multiple declaration
-- case as a sequence of single declarations, using the More_Ids and
-- Prev_Ids flags to preserve the original source form as described
-- in the section on "Handling of Defining Identifier Lists".
-- N_Component_Declaration
-- Sloc points to first identifier
-- Defining_Identifier
-- Component_Definition
-- Expression (set to Empty if no default expression)
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
-------------------------
-- 3.8.1 Variant Part --
-------------------------
-- VARIANT_PART ::=
-- case discriminant_DIRECT_NAME is
-- VARIANT {VARIANT}
-- end case;
-- Note: the variants list can contain pragmas as well as variants.
-- In a properly formed program there is at least one variant.
-- N_Variant_Part
-- Sloc points to CASE
-- Name
-- Variants
--------------------
-- 3.8.1 Variant --
--------------------
-- VARIANT ::=
-- when DISCRETE_CHOICE_LIST =>
-- COMPONENT_LIST
-- N_Variant
-- Sloc points to WHEN
-- Discrete_Choices
-- Component_List
-- Enclosing_Variant
-- Present_Expr
-- Dcheck_Function
-- Has_SP_Choice
-- Note: in the list of Discrete_Choices, the tree passed to the back
-- end does not have choice entries corresponding to names of statically
-- predicated subtypes. Such entries are always expanded out to the list
-- of equivalent values or ranges.
---------------------------------
-- 3.8.1 Discrete Choice List --
---------------------------------
-- DISCRETE_CHOICE_LIST ::= DISCRETE_CHOICE {| DISCRETE_CHOICE}
----------------------------
-- 3.8.1 Discrete Choice --
----------------------------
-- DISCRETE_CHOICE ::= EXPRESSION | DISCRETE_RANGE | others
-- Note: in Ada 83 mode, the expression must be a simple expression
-- The only choice that appears explicitly is the OTHERS choice, as
-- defined here. Other cases of discrete choice (expression and
-- discrete range) appear directly. This production is also used
-- for the OTHERS possibility of an exception choice.
-- Note: in accordance with the syntax, the parser does not check that
-- OTHERS appears at the end on its own in a choice list context. This
-- is a semantic check.
-- N_Others_Choice
-- Sloc points to OTHERS
-- Others_Discrete_Choices
-- All_Others
----------------------------------
-- 3.9.1 Record Extension Part --
----------------------------------
-- RECORD_EXTENSION_PART ::= with RECORD_DEFINITION
-- Note: record extension parts are not permitted in Ada 83 mode
--------------------------------------
-- 3.9.4 Interface Type Definition --
--------------------------------------
-- INTERFACE_TYPE_DEFINITION ::=
-- [limited | task | protected | synchronized]
-- interface [interface_list]
-- Note: Interfaces are implemented with N_Record_Definition and
-- N_Derived_Type_Definition nodes because most of the support
-- for the analysis of abstract types has been reused to
-- analyze abstract interfaces.
----------------------------------
-- 3.10 Access Type Definition --
----------------------------------
-- ACCESS_TYPE_DEFINITION ::=
-- ACCESS_TO_OBJECT_DEFINITION
-- | ACCESS_TO_SUBPROGRAM_DEFINITION
--------------------------
-- 3.10 Null Exclusion --
--------------------------
-- NULL_EXCLUSION ::= not null
---------------------------------------
-- 3.10 Access To Object Definition --
---------------------------------------
-- ACCESS_TO_OBJECT_DEFINITION ::=
-- [NULL_EXCLUSION] access [GENERAL_ACCESS_MODIFIER]
-- SUBTYPE_INDICATION
-- N_Access_To_Object_Definition
-- Sloc points to ACCESS
-- All_Present
-- Null_Exclusion_Present
-- Null_Excluding_Subtype
-- Subtype_Indication
-- Constant_Present
-----------------------------------
-- 3.10 General Access Modifier --
-----------------------------------
-- GENERAL_ACCESS_MODIFIER ::= all | constant
-- Note: general access modifiers are not permitted in Ada 83 mode
-- There is no explicit node in the tree for general access modifier.
-- Instead the All_Present or Constant_Present flags are set in the
-- parent node.
-------------------------------------------
-- 3.10 Access To Subprogram Definition --
-------------------------------------------
-- ACCESS_TO_SUBPROGRAM_DEFINITION
-- [NULL_EXCLUSION] access [protected] procedure PARAMETER_PROFILE
-- | [NULL_EXCLUSION] access [protected] function
-- PARAMETER_AND_RESULT_PROFILE
-- Note: access to subprograms are not permitted in Ada 83 mode
-- N_Access_Function_Definition
-- Sloc points to ACCESS
-- Null_Exclusion_Present
-- Null_Exclusion_In_Return_Present
-- Protected_Present
-- Parameter_Specifications (set to No_List if no formal part)
-- Result_Definition result subtype (subtype mark or access def)
-- N_Access_Procedure_Definition
-- Sloc points to ACCESS
-- Null_Exclusion_Present
-- Protected_Present
-- Parameter_Specifications (set to No_List if no formal part)
-----------------------------
-- 3.10 Access Definition --
-----------------------------
-- ACCESS_DEFINITION ::=
-- [NULL_EXCLUSION] access [GENERAL_ACCESS_MODIFIER] SUBTYPE_MARK
-- | ACCESS_TO_SUBPROGRAM_DEFINITION
-- Note: access to subprograms are an Ada 2005 (AI-254) extension
-- N_Access_Definition
-- Sloc points to ACCESS
-- Null_Exclusion_Present
-- All_Present
-- Constant_Present
-- Subtype_Mark
-- Access_To_Subprogram_Definition (set to Empty if not present)
-----------------------------------------
-- 3.10.1 Incomplete Type Declaration --
-----------------------------------------
-- INCOMPLETE_TYPE_DECLARATION ::=
-- type DEFINING_IDENTIFIER [DISCRIMINANT_PART] [IS TAGGED];
-- N_Incomplete_Type_Declaration
-- Sloc points to TYPE
-- Defining_Identifier
-- Discriminant_Specifications (set to No_List if no
-- discriminant part, or if the discriminant part is an
-- unknown discriminant part)
-- Premature_Use used for improved diagnostics.
-- Unknown_Discriminants_Present set if (<>) discriminant
-- Tagged_Present
----------------------------
-- 3.11 Declarative Part --
----------------------------
-- DECLARATIVE_PART ::= {DECLARATIVE_ITEM}
-- Note: although the parser enforces the syntactic requirement that
-- a declarative part can contain only declarations, the semantic
-- processing may add statements to the list of actions in a
-- declarative part, so the code generator should be prepared
-- to accept a statement in this position.
----------------------------
-- 3.11 Declarative Item --
----------------------------
-- DECLARATIVE_ITEM ::= BASIC_DECLARATIVE_ITEM | BODY
----------------------------------
-- 3.11 Basic Declarative Item --
----------------------------------
-- BASIC_DECLARATIVE_ITEM ::=
-- BASIC_DECLARATION | REPRESENTATION_CLAUSE | USE_CLAUSE
----------------
-- 3.11 Body --
----------------
-- BODY ::= PROPER_BODY | BODY_STUB
-----------------------
-- 3.11 Proper Body --
-----------------------
-- PROPER_BODY ::=
-- SUBPROGRAM_BODY | PACKAGE_BODY | TASK_BODY | PROTECTED_BODY
---------------
-- 4.1 Name --
---------------
-- NAME ::=
-- DIRECT_NAME | EXPLICIT_DEREFERENCE
-- | INDEXED_COMPONENT | SLICE
-- | SELECTED_COMPONENT | ATTRIBUTE_REFERENCE
-- | TYPE_CONVERSION | FUNCTION_CALL
-- | CHARACTER_LITERAL
----------------------
-- 4.1 Direct Name --
----------------------
-- DIRECT_NAME ::= IDENTIFIER | OPERATOR_SYMBOL
-----------------
-- 4.1 Prefix --
-----------------
-- PREFIX ::= NAME | IMPLICIT_DEREFERENCE
-------------------------------
-- 4.1 Explicit Dereference --
-------------------------------
-- EXPLICIT_DEREFERENCE ::= NAME . all
-- N_Explicit_Dereference
-- Sloc points to ALL
-- Prefix
-- Actual_Designated_Subtype
-- Has_Dereference_Action
-- Atomic_Sync_Required
-- plus fields for expression
-------------------------------
-- 4.1 Implicit Dereference --
-------------------------------
-- IMPLICIT_DEREFERENCE ::= NAME
------------------------------
-- 4.1.1 Indexed Component --
------------------------------
-- INDEXED_COMPONENT ::= PREFIX (EXPRESSION {, EXPRESSION})
-- Note: the parser may generate this node in some situations where it
-- should be a function call. The semantic pass must correct this
-- misidentification (which is inevitable at the parser level).
-- N_Indexed_Component
-- Sloc contains a copy of the Sloc value of the Prefix
-- Prefix
-- Expressions
-- Generalized_Indexing
-- Atomic_Sync_Required
-- plus fields for expression
-- Note: if any of the subscripts requires a range check, then the
-- Do_Range_Check flag is set on the corresponding expression, with
-- the index type being determined from the type of the Prefix, which
-- references the array being indexed.
-- Note: in a fully analyzed and expanded indexed component node, and
-- hence in any such node that gigi sees, if the prefix is an access
-- type, then an explicit dereference operation has been inserted.
------------------
-- 4.1.2 Slice --
------------------
-- SLICE ::= PREFIX (DISCRETE_RANGE)
-- Note: an implicit subtype is created to describe the resulting
-- type, so that the bounds of this type are the bounds of the slice.
-- N_Slice
-- Sloc points to first token of prefix
-- Prefix
-- Discrete_Range
-- plus fields for expression
-------------------------------
-- 4.1.3 Selected Component --
-------------------------------
-- SELECTED_COMPONENT ::= PREFIX . SELECTOR_NAME
-- Note: selected components that are semantically expanded names get
-- changed during semantic processing into the separate N_Expanded_Name
-- node. See description of this node in the section on semantic nodes.
-- N_Selected_Component
-- Sloc points to the period
-- Prefix
-- Selector_Name
-- Associated_Node
-- Do_Discriminant_Check
-- Is_In_Discriminant_Check
-- Atomic_Sync_Required
-- Is_Prefixed_Call
-- plus fields for expression
--------------------------
-- 4.1.3 Selector Name --
--------------------------
-- SELECTOR_NAME ::= IDENTIFIER | CHARACTER_LITERAL | OPERATOR_SYMBOL
--------------------------------
-- 4.1.4 Attribute Reference --
--------------------------------
-- ATTRIBUTE_REFERENCE ::= PREFIX ' ATTRIBUTE_DESIGNATOR
-- Note: the syntax is quite ambiguous at this point. Consider:
-- A'Length (X) X is part of the attribute designator
-- A'Pos (X) X is an explicit actual parameter of function A'Pos
-- A'Class (X) X is the expression of a type conversion
-- It would be possible for the parser to distinguish these cases
-- by looking at the attribute identifier. However, that would mean
-- more work in introducing new implementation defined attributes,
-- and also it would mean that special processing for attributes
-- would be scattered around, instead of being centralized in the
-- semantic routine that handles an N_Attribute_Reference node.
-- Consequently, the parser in all the above cases stores the
-- expression (X in these examples) as a single element list in
-- in the Expressions field of the N_Attribute_Reference node.
-- Similarly, for attributes like Max which take two arguments,
-- we store the two arguments as a two element list in the
-- Expressions field. Of course it is clear at parse time that
-- this case is really a function call with an attribute as the
-- prefix, but it turns out to be convenient to handle the two
-- argument case in a similar manner to the one argument case,
-- and indeed in general the parser will accept any number of
-- expressions in this position and store them as a list in the
-- attribute reference node. This allows for future addition of
-- attributes that take more than two arguments.
-- Note: named associates are not permitted in function calls where
-- the function is an attribute (see RM 6.4(3)) so it is legitimate
-- to skip the normal subprogram argument processing.
-- Note: for the attributes whose designators are technically keywords,
-- i.e. digits, access, delta, range, the Attribute_Name field contains
-- the corresponding name, even though no identifier is involved.
-- Note: the generated code may contain stream attributes applied to
-- limited types for which no stream routines exist officially. In such
-- case, the result is to use the stream attribute for the underlying
-- full type, or in the case of a protected type, the components
-- (including any discriminants) are merely streamed in order.
-- See Exp_Attr for a complete description of which attributes are
-- passed onto Gigi, and which are handled entirely by the front end.
-- Gigi restriction: For the Pos attribute, the prefix cannot be
-- a non-standard enumeration type or a nonzero/zero semantics
-- boolean type, so the value is simply the stored representation.
-- Gigi requirement: For the Mechanism_Code attribute, if the prefix
-- references a subprogram that is a renaming, then the front end must
-- rewrite the attribute to refer directly to the renamed entity.
-- Note: syntactically the prefix of an attribute reference must be a
-- name, and this (somewhat artificial) requirement is enforced by the
-- parser. However, for many attributes, such as 'Valid, it is quite
-- reasonable to apply the attribute to any value, and hence to any
-- expression. Internally in the tree, the prefix is an expression which
-- does not have to be a name, and this is handled fine by the semantic
-- analysis and expansion, and back ends. This arises for the case of
-- attribute references built by the expander (e.g. 'Valid for the case
-- of an implicit validity check).
-- Note: In generated code, the Address and Unrestricted_Access
-- attributes can be applied to any expression, and the meaning is
-- to create an object containing the value (the object is in the
-- current stack frame), and pass the address of this value. If the
-- Must_Be_Byte_Aligned flag is set, then the object whose address
-- is taken must be on a byte (storage unit) boundary, and if it is
-- not (or may not be), then the generated code must create a copy
-- that is byte aligned, and pass the address of this copy.
-- N_Attribute_Reference
-- Sloc points to apostrophe
-- Prefix (general expression, see note above)
-- Attribute_Name identifier name from attribute designator
-- Expressions (set to No_List if no associated expressions)
-- Entity used if the attribute yields a type
-- Associated_Node
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Header_Size_Added
-- Redundant_Use
-- Must_Be_Byte_Aligned
-- plus fields for expression
-- Note: in Modify_Tree_For_C mode, Max and Min attributes are expanded
-- into equivalent if expressions, properly taking care of side effects.
---------------------------------
-- 4.1.4 Attribute Designator --
---------------------------------
-- ATTRIBUTE_DESIGNATOR ::=
-- IDENTIFIER [(static_EXPRESSION)]
-- | access | delta | digits
-- There is no explicit node in the tree for an attribute designator.
-- Instead the Attribute_Name and Expressions fields of the parent
-- node (N_Attribute_Reference node) hold the information.
-- Note: if ACCESS, DELTA, or DIGITS appears in an attribute
-- designator, then they are treated as identifiers internally
-- rather than the keywords of the same name.
--------------------------------------
-- 4.1.4 Range Attribute Reference --
--------------------------------------
-- RANGE_ATTRIBUTE_REFERENCE ::= PREFIX ' RANGE_ATTRIBUTE_DESIGNATOR
-- A range attribute reference is represented in the tree using the
-- normal N_Attribute_Reference node.
---------------------------------------
-- 4.1.4 Range Attribute Designator --
---------------------------------------
-- RANGE_ATTRIBUTE_DESIGNATOR ::= Range [(static_EXPRESSION)]
-- A range attribute designator is represented in the tree using the
-- normal N_Attribute_Reference node.
--------------------
-- 4.3 Aggregate --
--------------------
-- AGGREGATE ::=
-- RECORD_AGGREGATE | EXTENSION_AGGREGATE | ARRAY_AGGREGATE
-----------------------------
-- 4.3.1 Record Aggregate --
-----------------------------
-- RECORD_AGGREGATE ::= (RECORD_COMPONENT_ASSOCIATION_LIST)
-- N_Aggregate
-- Sloc points to left parenthesis
-- Expressions (set to No_List if none or null record case)
-- Component_Associations (set to No_List if none)
-- Null_Record_Present
-- Aggregate_Bounds
-- Associated_Node
-- Compile_Time_Known_Aggregate
-- Expansion_Delayed
-- Has_Self_Reference
-- Is_Homogeneous_Aggregate
-- plus fields for expression
-- Note: this structure is used for both record and array aggregates
-- since the two cases are not separable by the parser. The parser
-- makes no attempt to enforce consistency here, so it is up to the
-- semantic phase to make sure that the aggregate is consistent (i.e.
-- that it is not a "half-and-half" case that mixes record and array
-- syntax). In particular, for a record aggregate, the expressions
-- field will be set if there are positional associations.
-- Note: N_Aggregate is not used for all aggregates; in particular,
-- there is a separate node kind for extension aggregates.
-- Note: gigi/gcc can handle array aggregates correctly providing that
-- they are entirely positional, and the array subtype involved has a
-- known at compile time length and is not bit packed, or a convention
-- Fortran array with more than one dimension. If these conditions
-- are not met, then the front end must translate the aggregate into
-- an appropriate set of assignments into a temporary.
-- Note: for the record aggregate case, gigi/gcc can handle most cases
-- of record aggregates, including those for packed, and rep-claused
-- records, and also variant records, providing that there are no
-- variable length fields whose size is not known at compile time,
-- and providing that the aggregate is presented in fully named form.
-- The other situation in which array aggregates and record aggregates
-- cannot be passed to the back end is if assignment to one or more
-- components itself needs expansion, e.g. in the case of an assignment
-- of an object of a controlled type. In such cases, the front end
-- must expand the aggregate to a series of assignments, and apply
-- the required expansion to the individual assignment statements.
----------------------------------------------
-- 4.3.1 Record Component Association List --
----------------------------------------------
-- RECORD_COMPONENT_ASSOCIATION_LIST ::=
-- RECORD_COMPONENT_ASSOCIATION {, RECORD_COMPONENT_ASSOCIATION}
-- | null record
-- There is no explicit node in the tree for a record component
-- association list. Instead the Null_Record_Present flag is set in
-- the parent node for the NULL RECORD case.
------------------------------------------------------
-- 4.3.1 Record Component Association (also 4.3.3) --
------------------------------------------------------
-- RECORD_COMPONENT_ASSOCIATION ::=
-- [COMPONENT_CHOICE_LIST =>] EXPRESSION
-- N_Component_Association
-- Sloc points to first selector name
-- Choices
-- Expression (empty if Box_Present)
-- Loop_Actions
-- Box_Present
-- Inherited_Discriminant
-- Binding_Chars
-- Note: this structure is used for both record component associations
-- and array component associations, since the two cases aren't always
-- separable by the parser. The choices list may represent either a
-- list of selector names in the record aggregate case, or a list of
-- discrete choices in the array aggregate case or an N_Others_Choice
-- node (which appears as a singleton list). Box_Present gives support
-- to Ada 2005 (AI-287). Binding_Chars is only set if GNAT extensions
-- are enabled and the given component association occurs within a
-- choice_expression; in this case, it is the Name_Id, if any, specified
-- via either of two syntactic forms: "Foo => Bar is Abc" or
-- "Foo => <Abc>".
----------------------------------
-- 4.3.1 Component Choice List --
----------------------------------
-- COMPONENT_CHOICE_LIST ::=
-- component_SELECTOR_NAME {| component_SELECTOR_NAME}
-- | others
-- The entries of a component choice list appear in the Choices list of
-- the associated N_Component_Association, as either selector names, or
-- as an N_Others_Choice node.
--------------------------------
-- 4.3.2 Extension Aggregate --
--------------------------------
-- EXTENSION_AGGREGATE ::=
-- (ANCESTOR_PART with RECORD_COMPONENT_ASSOCIATION_LIST)
-- Note: extension aggregates are not permitted in Ada 83 mode
-- N_Extension_Aggregate
-- Sloc points to left parenthesis
-- Ancestor_Part
-- Associated_Node
-- Expressions (set to No_List if none or null record case)
-- Component_Associations (set to No_List if none)
-- Null_Record_Present
-- Expansion_Delayed
-- Has_Self_Reference
-- plus fields for expression
--------------------------
-- 4.3.2 Ancestor Part --
--------------------------
-- ANCESTOR_PART ::= EXPRESSION | SUBTYPE_MARK
----------------------------
-- 4.3.3 Array Aggregate --
----------------------------
-- ARRAY_AGGREGATE ::=
-- POSITIONAL_ARRAY_AGGREGATE | NAMED_ARRAY_AGGREGATE
---------------------------------------
-- 4.3.3 Positional Array Aggregate --
---------------------------------------
-- POSITIONAL_ARRAY_AGGREGATE ::=
-- (EXPRESSION, EXPRESSION {, EXPRESSION})
-- | (EXPRESSION {, EXPRESSION}, others => EXPRESSION)
-- See Record_Aggregate (4.3.1) for node structure
----------------------------------
-- 4.3.3 Named Array Aggregate --
----------------------------------
-- NAMED_ARRAY_AGGREGATE ::=
-- (ARRAY_COMPONENT_ASSOCIATION {, ARRAY_COMPONENT_ASSOCIATION})
-- See Record_Aggregate (4.3.1) for node structure
----------------------------------------
-- 4.3.3 Array Component Association --
----------------------------------------
-- ARRAY_COMPONENT_ASSOCIATION ::=
-- DISCRETE_CHOICE_LIST => EXPRESSION
-- | ITERATED_COMPONENT_ASSOCIATION
-- See Record_Component_Association (4.3.1) for node structure
-- The iterated_component_association is introduced into the
-- Corrigendum of Ada_2012 by AI12-061.
------------------------------------------
-- 4.3.3 Iterated component Association --
------------------------------------------
-- ITERATED_COMPONENT_ASSOCIATION ::=
-- for DEFINING_IDENTIFIER in DISCRETE_CHOICE_LIST => EXPRESSION
-- N_Iterated_Component_Association
-- Sloc points to FOR
-- Defining_Identifier
-- Iterator_Specification (set to Empty if no Iterator_Spec)
-- Expression
-- Discrete_Choices
-- Loop_Actions
-- Box_Present
-- Note that Box_Present is always False, but it is intentionally added
-- for completeness.
----------------------------
-- 4.3.4 Delta Aggregate --
----------------------------
-- N_Delta_Aggregate
-- Sloc points to left parenthesis
-- Expression
-- Component_Associations
-- Etype
---------------------------------
-- 3.4.5 Comtainer_Aggregates --
---------------------------------
-- N_Iterated_Element_Association
-- Key_Expression
-- Iterator_Specification
-- Expression
-- Loop_Parameter_Specification
-- Loop_Actions
-- Box_Present
-- Exactly one of Iterator_Specification or Loop_Parameter_
-- specification is present. If the Key_Expression is absent,
-- the construct is parsed as an Iterated_Component_Association,
-- and legality checks are performed during semantic analysis.
-- Both iterated associations are Ada 2022 features that are
-- expanded during aggregate construction, and do not appear in
-- expanded code.
--------------------------------------------------
-- 4.4 Expression/Relation/Term/Factor/Primary --
--------------------------------------------------
-- EXPRESSION ::=
-- RELATION {LOGICAL_OPERATOR RELATION}
-- CHOICE_EXPRESSION ::=
-- CHOICE_RELATION {LOGICAL_OPERATOR CHOICE_RELATION}
-- CHOICE_RELATION ::=
-- SIMPLE_EXPRESSION [RELATIONAL_OPERATOR SIMPLE_EXPRESSION]
-- RELATION ::=
-- SIMPLE_EXPRESSION [not] in MEMBERSHIP_CHOICE_LIST
-- | RAISE_EXPRESSION
-- MEMBERSHIP_CHOICE_LIST ::=
-- MEMBERSHIP_CHOICE {'|' MEMBERSHIP CHOICE}
-- MEMBERSHIP_CHOICE ::=
-- CHOICE_EXPRESSION | RANGE | SUBTYPE_MARK
-- LOGICAL_OPERATOR ::= and | and then | or | or else | xor
-- SIMPLE_EXPRESSION ::=
-- [UNARY_ADDING_OPERATOR] TERM {BINARY_ADDING_OPERATOR TERM}
-- TERM ::= FACTOR {MULTIPLYING_OPERATOR FACTOR}
-- FACTOR ::= PRIMARY [** PRIMARY] | abs PRIMARY | not PRIMARY
-- No nodes are generated for any of these constructs. Instead, the
-- node for the operator appears directly. When we refer to an
-- expression in this description, we mean any of the possible
-- constituent components of an expression (e.g. identifier is
-- an example of an expression).
-- Note: the above syntax is that Ada 2012 syntax which restricts
-- choice relations to simple expressions to avoid ambiguities in
-- some contexts with set membership notation. It has been decided
-- that in retrospect, the Ada 95 change allowing general expressions
-- in this context was a mistake, so we have reverted to the above
-- syntax in Ada 95 and Ada 2005 modes (the restriction to simple
-- expressions was there in Ada 83 from the start).
------------------
-- 4.4 Primary --
------------------
-- PRIMARY ::=
-- NUMERIC_LITERAL | null
-- | STRING_LITERAL | AGGREGATE
-- | NAME | QUALIFIED_EXPRESSION
-- | ALLOCATOR | (EXPRESSION)
-- Usually there is no explicit node in the tree for primary. Instead
-- the constituent (e.g. AGGREGATE) appears directly. There are two
-- exceptions. First, there is an explicit node for a null primary.
-- N_Null
-- Sloc points to NULL
-- plus fields for expression
-- Second, the case of (EXPRESSION) is handled specially. Ada requires
-- that the parser keep track of which subexpressions are enclosed
-- in parentheses, and how many levels of parentheses are used. This
-- information is required for optimization purposes, and also for
-- some semantic checks (e.g. (((1))) in a procedure spec does not
-- conform with ((((1)))) in the body).
-- The parentheses are recorded by keeping a Paren_Count field in every
-- subexpression node (it is actually present in all nodes, but only
-- used in subexpression nodes). This count records the number of
-- levels of parentheses. If the number of levels in the source exceeds
-- the maximum accommodated by this count, then the count is simply left
-- at the maximum value. This means that there are some pathological
-- cases of failure to detect conformance failures (e.g. an expression
-- with 500 levels of parens will conform with one with 501 levels),
-- but we do not need to lose sleep over this.
-- Historical note: in versions of GNAT prior to 1.75, there was a node
-- type N_Parenthesized_Expression used to accurately record unlimited
-- numbers of levels of parentheses. However, it turned out to be a
-- real nuisance to have to take into account the possible presence of
-- this node during semantic analysis, since basically parentheses have
-- zero relevance to semantic analysis.
-- Note: the level of parentheses always present in things like
-- aggregates does not count, only the parentheses in the primary
-- (EXPRESSION) affect the setting of the Paren_Count field.
-- 2nd Note: the contents of the Expression field must be ignored (i.e.
-- treated as though it were Empty) if No_Initialization is set True.
--------------------------------------
-- 4.5 Short-Circuit Control Forms --
--------------------------------------
-- EXPRESSION ::=
-- RELATION {and then RELATION} | RELATION {or else RELATION}
-- Gigi restriction: For both these control forms, the operand and
-- result types are always Standard.Boolean. The expander inserts the
-- required conversion operations where needed to ensure this is the
-- case.
-- N_And_Then
-- Sloc points to AND of AND THEN
-- Left_Opnd
-- Right_Opnd
-- Actions
-- plus fields for expression
-- N_Or_Else
-- Sloc points to OR of OR ELSE
-- Left_Opnd
-- Right_Opnd
-- Actions
-- plus fields for expression
-- Note: The Actions field is used to hold actions associated with
-- the right hand operand. These have to be treated specially since
-- they are not unconditionally executed. See Insert_Actions for a
-- more detailed description of how these actions are handled.
---------------------------
-- 4.5 Membership Tests --
---------------------------
-- RELATION ::=
-- SIMPLE_EXPRESSION [not] in MEMBERSHIP_CHOICE_LIST
-- MEMBERSHIP_CHOICE_LIST ::=
-- MEMBERSHIP_CHOICE {'|' MEMBERSHIP CHOICE}
-- MEMBERSHIP_CHOICE ::=
-- CHOICE_EXPRESSION | RANGE | SUBTYPE_MARK
-- Note: although the grammar above allows only a range or a subtype
-- mark, the parser in fact will accept any simple expression in place
-- of a subtype mark. This means that the semantic analyzer must be able
-- to deal with, and diagnose a simple expression other than a name for
-- the right operand. This simplifies error recovery in the parser.
-- The Alternatives field below is present only if there is more than
-- one Membership_Choice present (which is legitimate only in Ada 2012
-- mode) in which case Right_Opnd is Empty, and Alternatives contains
-- the list of choices. In the tree passed to the back end, Alternatives
-- is always No_List, and Right_Opnd is set (i.e. the expansion circuit
-- expands out the complex set membership case using simple membership
-- and equality operations).
-- Should we rename Alternatives here to Membership_Choices ???
-- N_In
-- Sloc points to IN
-- Left_Opnd
-- Right_Opnd
-- Alternatives (set to No_List if only one set alternative)
-- No_Minimize_Eliminate
-- plus fields for expression
-- N_Not_In
-- Sloc points to NOT of NOT IN
-- Left_Opnd
-- Right_Opnd
-- Alternatives (set to No_List if only one set alternative)
-- No_Minimize_Eliminate
-- plus fields for expression
--------------------
-- 4.5 Operators --
--------------------
-- LOGICAL_OPERATOR ::= and | or | xor
-- RELATIONAL_OPERATOR ::= = | /= | < | <= | > | >=
-- BINARY_ADDING_OPERATOR ::= + | - | &
-- UNARY_ADDING_OPERATOR ::= + | -
-- MULTIPLYING_OPERATOR ::= * | / | mod | rem
-- HIGHEST_PRECEDENCE_OPERATOR ::= ** | abs | not
-- Gigi restriction: Gigi will never be given * / mod rem nodes with
-- fixed-point operands. All handling of smalls for multiplication and
-- division is handled by the front end (mod and rem result only from
-- expansion). Gigi thus never needs to worry about small values (for
-- other operators operating on fixed-point, e.g. addition, the small
-- value does not have any semantic effect anyway, these are always
-- integer operations).
-- Gigi restriction: For all operators taking Boolean operands, the
-- type is always Standard.Boolean. The expander inserts the required
-- conversion operations where needed to ensure this is the case.
-- N_Op_And
-- Sloc points to AND
-- Do_Length_Check
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Or
-- Sloc points to OR
-- Do_Length_Check
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Xor
-- Sloc points to XOR
-- Do_Length_Check
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Eq
-- Sloc points to =
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Ne
-- Sloc points to /=
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Lt
-- Sloc points to <
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Le
-- Sloc points to <=
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Gt
-- Sloc points to >
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Ge
-- Sloc points to >=
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Add
-- Sloc points to + (binary)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Subtract
-- Sloc points to - (binary)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Concat
-- Sloc points to &
-- Is_Component_Left_Opnd
-- Is_Component_Right_Opnd
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Multiply
-- Sloc points to *
-- Rounded_Result
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Divide
-- Sloc points to /
-- Do_Division_Check
-- Rounded_Result
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Mod
-- Sloc points to MOD
-- Do_Division_Check
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Rem
-- Sloc points to REM
-- Do_Division_Check
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Expon
-- Sloc points to **
-- Is_Power_Of_2_For_Shift
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Plus
-- Sloc points to + (unary)
-- plus fields for unary operator
-- plus fields for expression
-- N_Op_Minus
-- Sloc points to - (unary)
-- plus fields for unary operator
-- plus fields for expression
-- N_Op_Abs
-- Sloc points to ABS
-- plus fields for unary operator
-- plus fields for expression
-- N_Op_Not
-- Sloc points to NOT
-- plus fields for unary operator
-- plus fields for expression
-- See also shift operators in section B.2
-- Note on fixed-point operations passed to Gigi: For adding operators,
-- the semantics is to treat these simply as integer operations, with
-- the small values being ignored (the bounds are already stored in
-- units of small, so that constraint checking works as usual). For the
-- case of multiply/divide/rem/mod operations, Gigi will never see them.
-- Note on equality/inequality tests for records. In the expanded tree,
-- record comparisons are always expanded to be a series of component
-- comparisons, so the back end will never see an equality or inequality
-- operation with operands of a record type.
-- Note on overflow handling: When the overflow checking mode is set to
-- MINIMIZED or ELIMINATED, nodes for signed arithmetic operations may
-- be modified to use a larger type for the operands and result. In
-- the case where the computed range exceeds that of Long_Long_Integer,
-- and we are running in ELIMINATED mode, the operator node will be
-- changed to be a call to the appropriate routine in System.Bignums.
-- Note: In Modify_Tree_For_C mode, we do not generate an N_Op_Mod node
-- for signed integer types (since there is no equivalent operator in
-- C). Instead we rewrite such an operation in terms of REM (which is
-- % in C) and other C-available operators.
------------------------------------
-- 4.5.7 Conditional Expressions --
------------------------------------
-- CONDITIONAL_EXPRESSION ::= IF_EXPRESSION | CASE_EXPRESSION
--------------------------
-- 4.5.7 If Expression --
--------------------------
-- IF_EXPRESSION ::=
-- if CONDITION then DEPENDENT_EXPRESSION
-- {elsif CONDITION then DEPENDENT_EXPRESSION}
-- [else DEPENDENT_EXPRESSION]
-- DEPENDENT_EXPRESSION ::= EXPRESSION
-- Note: if we have (IF x1 THEN x2 ELSIF x3 THEN x4 ELSE x5) then it
-- is represented as (IF x1 THEN x2 ELSE (IF x3 THEN x4 ELSE x5)) and
-- the Is_Elsif flag is set on the inner if expression.
-- N_If_Expression
-- Sloc points to IF or ELSIF keyword
-- Expressions
-- Then_Actions
-- Else_Actions
-- Is_Elsif (set if comes from ELSIF)
-- Do_Overflow_Check
-- plus fields for expression
-- Expressions here is a three-element list, whose first element is the
-- condition, the second element is the dependent expression after THEN
-- and the third element is the dependent expression after the ELSE
-- (explicitly set to True if missing).
-- Note: the Then_Actions and Else_Actions fields are always set to
-- No_List in the tree passed to the back end. These are used only
-- for temporary processing purposes in the expander. Even though they
-- are semantic fields, their parent pointers are set because analysis
-- of actions nodes in those lists may generate additional actions that
-- need to know their insertion point (for example for the creation of
-- transient scopes).
-- Note: in the tree passed to the back end, if the result type is
-- an unconstrained array, the if expression can only appears in the
-- initializing expression of an object declaration (this avoids the
-- back end having to create a variable length temporary on the fly).
----------------------------
-- 4.5.7 Case Expression --
----------------------------
-- CASE_EXPRESSION ::=
-- case SELECTING_EXPRESSION is
-- CASE_EXPRESSION_ALTERNATIVE
-- {,CASE_EXPRESSION_ALTERNATIVE}
-- Note that the Alternatives cannot include pragmas (this contrasts
-- with the situation of case statements where pragmas are allowed).
-- N_Case_Expression
-- Sloc points to CASE
-- Expression (the selecting expression)
-- Alternatives (the case expression alternatives)
-- Etype
-- Do_Overflow_Check
----------------------------------------
-- 4.5.7 Case Expression Alternative --
----------------------------------------
-- CASE_EXPRESSION_ALTERNATIVE ::=
-- when DISCRETE_CHOICE_LIST =>
-- DEPENDENT_EXPRESSION
-- N_Case_Expression_Alternative
-- Sloc points to WHEN
-- Actions
-- Discrete_Choices
-- Expression
-- Has_SP_Choice
-- Note: The Actions field temporarily holds any actions associated with
-- evaluation of the Expression. During expansion of the case expression
-- these actions are wrapped into an N_Expressions_With_Actions node
-- replacing the original expression.
-- Note: this node never appears in the tree passed to the back end,
-- since the expander converts case expressions into case statements.
---------------------------------
-- 4.5.8 Quantified Expression --
---------------------------------
-- QUANTIFIED_EXPRESSION ::=
-- for QUANTIFIER LOOP_PARAMETER_SPECIFICATION => PREDICATE
-- | for QUANTIFIER ITERATOR_SPECIFICATION => PREDICATE
--
-- QUANTIFIER ::= all | some
-- At most one of (Iterator_Specification, Loop_Parameter_Specification)
-- is present at a time, in which case the other one is empty.
-- N_Quantified_Expression
-- Sloc points to FOR
-- Iterator_Specification
-- Loop_Parameter_Specification
-- Condition
-- All_Present
--------------------------
-- 4.6 Type Conversion --
--------------------------
-- TYPE_CONVERSION ::=
-- SUBTYPE_MARK (EXPRESSION) | SUBTYPE_MARK (NAME)
-- In the (NAME) case, the name is stored as the expression
-- Note: the parser never generates a type conversion node, since it
-- looks like an indexed component which is generated by preference.
-- The semantic pass must correct this misidentification.
-- Gigi handles conversions that involve no change in the root type,
-- and also all conversions from integer to floating-point types.
-- Conversions from floating-point to integer are only handled in
-- the case where Float_Truncate flag set. Other conversions from
-- floating-point to integer (involving rounding) and all conversions
-- involving fixed-point types are handled by the expander, unless the
-- Conversion_OK flag is set.
-- Sprint syntax if Float_Truncate set: X^(Y)
-- Sprint syntax if Conversion_OK set X?(Y)
-- Sprint syntax if both flags set X?^(Y)
-- Note: If either the operand or result type is fixed-point, Gigi will
-- only see a type conversion node with Conversion_OK set. The front end
-- takes care of all handling of small's for fixed-point conversions.
-- N_Type_Conversion
-- Sloc points to first token of subtype mark
-- Subtype_Mark
-- Expression
-- Do_Discriminant_Check
-- Do_Length_Check
-- Float_Truncate
-- Conversion_OK
-- Do_Overflow_Check
-- Rounded_Result
-- plus fields for expression
-- Note: if a range check is required, then the Do_Range_Check flag
-- is set in the Expression with the check being done against the
-- target type range (after the base type conversion, if any).
-------------------------------
-- 4.7 Qualified Expression --
-------------------------------
-- QUALIFIED_EXPRESSION ::=
-- SUBTYPE_MARK ' (EXPRESSION) | SUBTYPE_MARK ' AGGREGATE
-- Note: the parentheses in the (EXPRESSION) case are deemed to enclose
-- the expression, so the Expression field of this node always points
-- to a parenthesized expression in this case (i.e. Paren_Count will
-- always be non-zero for the referenced expression if it is not an
-- aggregate).
-- N_Qualified_Expression
-- Sloc points to apostrophe
-- Subtype_Mark
-- Expression expression or aggregate
-- Is_Qualified_Universal_Literal
-- plus fields for expression
--------------------
-- 4.8 Allocator --
--------------------
-- ALLOCATOR ::=
-- new [SUBPOOL_SPECIFICATION] SUBTYPE_INDICATION
-- | new [SUBPOOL_SPECIFICATION] QUALIFIED_EXPRESSION
--
-- SUBPOOL_SPECIFICATION ::= (subpool_handle_NAME)
-- Sprint syntax (when storage pool present)
-- new xxx (storage_pool = pool)
-- or
-- new (subpool) xxx (storage_pool = pool)
-- N_Allocator
-- Sloc points to NEW
-- Expression subtype indication or qualified expression
-- Subpool_Handle_Name (set to Empty if not present)
-- Storage_Pool
-- Procedure_To_Call
-- Alloc_For_BIP_Return
-- Null_Exclusion_Present
-- No_Initialization
-- Is_Static_Coextension
-- Do_Storage_Check
-- Is_Dynamic_Coextension
-- plus fields for expression
-- Note: like all nodes, the N_Allocator has the Comes_From_Source flag.
-- This flag has a special function in conjunction with the restriction
-- No_Implicit_Heap_Allocations, which will be triggered if this flag
-- is not set. This means that if a source allocator is replaced with
-- a constructed allocator, the Comes_From_Source flag should be copied
-- to the newly created allocator.
---------------------------------
-- 5.1 Sequence Of Statements --
---------------------------------
-- SEQUENCE_OF_STATEMENTS ::= STATEMENT {STATEMENT}
-- Note: Although the parser will not accept a declaration as a
-- statement, the semantic analyzer may insert declarations (e.g.
-- declarations of implicit types needed for execution of other
-- statements) into a sequence of statements, so the code generator
-- should be prepared to accept a declaration where a statement is
-- expected. Note also that pragmas can appear as statements.
--------------------
-- 5.1 Statement --
--------------------
-- STATEMENT ::=
-- {LABEL} SIMPLE_STATEMENT | {LABEL} COMPOUND_STATEMENT
-- There is no explicit node in the tree for a statement. Instead, the
-- individual statement appears directly. Labels are treated as a
-- kind of statement, i.e. they are linked into a statement list at
-- the point they appear, so the labeled statement appears following
-- the label or labels in the statement list.
---------------------------
-- 5.1 Simple Statement --
---------------------------
-- SIMPLE_STATEMENT ::= NULL_STATEMENT
-- | ASSIGNMENT_STATEMENT | EXIT_STATEMENT
-- | GOTO_STATEMENT | PROCEDURE_CALL_STATEMENT
-- | SIMPLE_RETURN_STATEMENT | ENTRY_CALL_STATEMENT
-- | REQUEUE_STATEMENT | DELAY_STATEMENT
-- | ABORT_STATEMENT | RAISE_STATEMENT
-- | CODE_STATEMENT
-----------------------------
-- 5.1 Compound Statement --
-----------------------------
-- COMPOUND_STATEMENT ::=
-- IF_STATEMENT | CASE_STATEMENT
-- | LOOP_STATEMENT | BLOCK_STATEMENT
-- | EXTENDED_RETURN_STATEMENT
-- | ACCEPT_STATEMENT | SELECT_STATEMENT
-------------------------
-- 5.1 Null Statement --
-------------------------
-- NULL_STATEMENT ::= null;
-- N_Null_Statement
-- Sloc points to NULL
-- Next_Rep_Item
----------------
-- 5.1 Label --
----------------
-- LABEL ::= <<label_STATEMENT_IDENTIFIER>>
-- Note that the occurrence of a label is not a defining identifier,
-- but rather a referencing occurrence. The defining occurrence is
-- in the implicit label declaration which occurs in the innermost
-- enclosing block.
-- N_Label
-- Sloc points to <<
-- Identifier direct name of statement identifier
-- Exception_Junk
-- Note: Before Ada 2012, a label is always followed by a statement,
-- and this is true in the tree even in Ada 2012 mode (the parser
-- inserts a null statement marked with Comes_From_Source False).
-------------------------------
-- 5.1 Statement Identifier --
-------------------------------
-- STATEMENT_IDENTIFIER ::= DIRECT_NAME
-- The IDENTIFIER of a STATEMENT_IDENTIFIER shall be an identifier
-- (not an OPERATOR_SYMBOL)
-------------------------------
-- 5.2 Assignment Statement --
-------------------------------
-- ASSIGNMENT_STATEMENT ::=
-- variable_NAME := EXPRESSION;
-- N_Assignment_Statement
-- Sloc points to :=
-- Name
-- Expression
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Do_Discriminant_Check
-- Do_Length_Check
-- Forwards_OK
-- Backwards_OK
-- No_Ctrl_Actions
-- Has_Target_Names
-- Is_Elaboration_Code
-- Componentwise_Assignment
-- Suppress_Assignment_Checks
-- Note: if a range check is required, then the Do_Range_Check flag
-- is set in the Expression (right hand side), with the check being
-- done against the type of the Name (left hand side).
-- Note: the back end places some restrictions on the form of the
-- Expression field. If the object being assigned to is Atomic, then
-- the Expression may not have the form of an aggregate (since this
-- might cause the back end to generate separate assignments). In this
-- case the front end must generate an extra temporary and initialize
-- this temporary as required (the temporary itself is not atomic).
------------------
-- Target_Name --
------------------
-- N_Target_Name
-- Sloc points to @
-- Etype
-- Note (Ada 2022): node is used during analysis as a placeholder for
-- the value of the LHS of the enclosing assignment statement. Node is
-- eventually rewritten together with enclosing assignment, and backends
-- are not aware of it.
-----------------------
-- 5.3 If Statement --
-----------------------
-- IF_STATEMENT ::=
-- if CONDITION then
-- SEQUENCE_OF_STATEMENTS
-- {elsif CONDITION then
-- SEQUENCE_OF_STATEMENTS}
-- [else
-- SEQUENCE_OF_STATEMENTS]
-- end if;
-- Gigi restriction: This expander ensures that the type of the
-- Condition fields is always Standard.Boolean, even if the type
-- in the source is some non-standard boolean type.
-- N_If_Statement
-- Sloc points to IF
-- Condition
-- Then_Statements
-- Elsif_Parts (set to No_List if none present)
-- Else_Statements (set to No_List if no else part present)
-- End_Span (set to Uint_0 if expander generated)
-- From_Conditional_Expression
-- N_Elsif_Part
-- Sloc points to ELSIF
-- Condition
-- Then_Statements
-- Condition_Actions
--------------------
-- 5.3 Condition --
--------------------
-- CONDITION ::= boolean_EXPRESSION
-------------------------
-- 5.4 Case Statement --
-------------------------
-- CASE_STATEMENT ::=
-- case EXPRESSION is
-- CASE_STATEMENT_ALTERNATIVE
-- {CASE_STATEMENT_ALTERNATIVE}
-- end case;
-- Note: the Alternatives can contain pragmas. These only occur at
-- the start of the list, since any pragmas occurring after the first
-- alternative are absorbed into the corresponding statement sequence.
-- N_Case_Statement
-- Sloc points to CASE
-- Expression
-- Alternatives
-- End_Span (set to Uint_0 if expander generated)
-- From_Conditional_Expression
-- Note: Before Ada 2012, a pragma in a statement sequence is always
-- followed by a statement, and this is true in the tree even in Ada
-- 2012 mode (the parser inserts a null statement marked with the flag
-- Comes_From_Source False).
-------------------------------------
-- 5.4 Case Statement Alternative --
-------------------------------------
-- CASE_STATEMENT_ALTERNATIVE ::=
-- when DISCRETE_CHOICE_LIST =>
-- SEQUENCE_OF_STATEMENTS
-- N_Case_Statement_Alternative
-- Sloc points to WHEN
-- Discrete_Choices
-- Statements
-- Has_SP_Choice
-- Multidefined_Bindings
-- Note: in the list of Discrete_Choices, the tree passed to the back
-- end does not have choice entries corresponding to names of statically
-- predicated subtypes. Such entries are always expanded out to the list
-- of equivalent values or ranges. Multidefined_Bindings is True iff
-- more than one choice is present and each choice contains
-- at least one component association having a non-null Binding_Chars
-- attribute; this can only occur if GNAT extensions are enabled
-- and the type of the case selector is composite.
-------------------------
-- 5.5 Loop Statement --
-------------------------
-- LOOP_STATEMENT ::=
-- [loop_STATEMENT_IDENTIFIER :]
-- [ITERATION_SCHEME] loop
-- SEQUENCE_OF_STATEMENTS
-- end loop [loop_IDENTIFIER];
-- Note: The occurrence of a loop label is not a defining identifier
-- but rather a referencing occurrence. The defining occurrence is in
-- the implicit label declaration which occurs in the innermost
-- enclosing block.
-- Note: there is always a loop statement identifier present in the
-- tree, even if none was given in the source. In the case where no loop
-- identifier is given in the source, the parser creates a name of the
-- form _Loop_n, where n is a decimal integer (the two underlines ensure
-- that the loop names created in this manner do not conflict with any
-- user defined identifiers), and the flag Has_Created_Identifier is set
-- to True. The only exception to the rule that all loop statement nodes
-- have identifiers occurs for loops constructed by the expander, and
-- the semantic analyzer will create and supply dummy loop identifiers
-- in these cases.
-- N_Loop_Statement
-- Sloc points to LOOP
-- Identifier loop identifier (set to Empty if no identifier)
-- Iteration_Scheme (set to Empty if no iteration scheme)
-- Statements
-- End_Label
-- Has_Created_Identifier
-- Is_Null_Loop
-- Suppress_Loop_Warnings
-- Note: the parser fills in the Identifier field if there is an
-- explicit loop identifier. Otherwise the parser leaves this field
-- set to Empty, and then the semantic processing for a loop statement
-- creates an identifier, setting the Has_Created_Identifier flag to
-- True. So after semantic analysis, the Identifier is always set,
-- referencing an identifier whose entity has an Ekind of E_Loop.
---------------------------
-- 5.5 Iteration Scheme --
---------------------------
-- ITERATION_SCHEME ::=
-- while CONDITION
-- | for LOOP_PARAMETER_SPECIFICATION
-- | for ITERATOR_SPECIFICATION
-- At most one of (Iterator_Specification, Loop_Parameter_Specification)
-- is present at a time, in which case the other one is empty. Both are
-- empty in the case of a WHILE loop.
-- Gigi restriction: The expander ensures that the type of the Condition
-- field is always Standard.Boolean, even if the type in the source is
-- some non-standard boolean type.
-- N_Iteration_Scheme
-- Sloc points to WHILE or FOR
-- Condition (set to Empty if FOR case)
-- Condition_Actions
-- Iterator_Specification (set to Empty if WHILE case)
-- Loop_Parameter_Specification (set to Empty if WHILE case)
---------------------------------------
-- 5.5 Loop Parameter Specification --
---------------------------------------
-- LOOP_PARAMETER_SPECIFICATION ::=
-- DEFINING_IDENTIFIER in [reverse] DISCRETE_SUBTYPE_DEFINITION
-- [Iterator_Filter]
-- Note: the optional Iterator_Filter is an Ada 2022 construct.
-- N_Loop_Parameter_Specification
-- Sloc points to first identifier
-- Defining_Identifier
-- Reverse_Present
-- Iterator_Filter (set to Empty if not present)
-- Discrete_Subtype_Definition
-----------------------------------
-- 5.5.1 Iterator Specification --
-----------------------------------
-- ITERATOR_SPECIFICATION ::=
-- DEFINING_IDENTIFIER in [reverse] NAME
-- | DEFINING_IDENTIFIER [: SUBTYPE_INDICATION] of [reverse] NAME
-- N_Iterator_Specification
-- Sloc points to defining identifier
-- Defining_Identifier
-- Name
-- Reverse_Present
-- Of_Present
-- Iterator_Filter (set to Empty if not present)
-- Subtype_Indication
-- Note: The Of_Present flag distinguishes the two forms
--------------------------
-- 5.6 Block Statement --
--------------------------
-- BLOCK_STATEMENT ::=
-- [block_STATEMENT_IDENTIFIER:]
-- [declare
-- DECLARATIVE_PART]
-- begin
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [block_IDENTIFIER];
-- Note that the occurrence of a block identifier is not a defining
-- identifier, but rather a referencing occurrence. The defining
-- occurrence is an E_Block entity declared by the implicit label
-- declaration which occurs in the innermost enclosing block statement
-- or body; the block identifier denotes that E_Block.
-- For block statements that come from source code, there is always a
-- block statement identifier present in the tree, denoting an E_Block.
-- In the case where no block identifier is given in the source,
-- the parser creates a name of the form B_n, where n is a decimal
-- integer, and the flag Has_Created_Identifier is set to True. Blocks
-- constructed by the expander usually have no identifier, and no
-- corresponding entity.
-- Note: the block statement created for an extended return statement
-- has an entity, and this entity is an E_Return_Statement, rather than
-- the usual E_Block.
-- Note: Exception_Junk is set for the wrapping blocks created during
-- local raise optimization (Exp_Ch11.Expand_Local_Exception_Handlers).
-- Note: from a control flow viewpoint, a block statement defines an
-- extended basic block, i.e. the entry of the block dominates every
-- statement in the sequence. When generating new statements with
-- exception handlers in the expander at the end of a sequence that
-- comes from source code, it can be necessary to wrap them all in a
-- block statement in order to expose the implicit control flow to
-- gigi and thus prevent it from issuing bogus control flow warnings.
-- N_Block_Statement
-- Sloc points to DECLARE or BEGIN
-- Identifier block direct name (set to Empty if not present)
-- Declarations (set to No_List if no DECLARE part)
-- Handled_Statement_Sequence
-- Activation_Chain_Entity
-- Cleanup_Actions
-- Has_Created_Identifier
-- Is_Asynchronous_Call_Block
-- Is_Task_Allocation_Block
-- Exception_Junk
-- Is_Abort_Block
-- Is_Finalization_Wrapper
-- Is_Initialization_Block
-- Is_Task_Master
-------------------------
-- 5.7 Exit Statement --
-------------------------
-- EXIT_STATEMENT ::= exit [loop_NAME] [when CONDITION];
-- Gigi restriction: The expander ensures that the type of the Condition
-- field is always Standard.Boolean, even if the type in the source is
-- some non-standard boolean type.
-- N_Exit_Statement
-- Sloc points to EXIT
-- Name (set to Empty if no loop name present)
-- Condition (set to Empty if no WHEN part present)
-- Next_Exit_Statement : Next exit on chain
-------------------------
-- 5.9 Goto Statement --
-------------------------
-- GOTO_STATEMENT ::= goto label_NAME;
-- N_Goto_Statement
-- Sloc points to GOTO
-- Name
-- Exception_Junk
---------------------------------
-- 6.1 Subprogram Declaration --
---------------------------------
-- SUBPROGRAM_DECLARATION ::=
-- SUBPROGRAM_SPECIFICATION
-- [ASPECT_SPECIFICATIONS];
-- N_Subprogram_Declaration
-- Sloc points to FUNCTION or PROCEDURE
-- Specification
-- Body_To_Inline
-- Corresponding_Body
-- Parent_Spec
-- Is_Entry_Barrier_Function
-- Is_Task_Body_Procedure
------------------------------------------
-- 6.1 Abstract Subprogram Declaration --
------------------------------------------
-- ABSTRACT_SUBPROGRAM_DECLARATION ::=
-- SUBPROGRAM_SPECIFICATION is abstract
-- [ASPECT_SPECIFICATIONS];
-- N_Abstract_Subprogram_Declaration
-- Sloc points to ABSTRACT
-- Specification
-----------------------------------
-- 6.1 Subprogram Specification --
-----------------------------------
-- SUBPROGRAM_SPECIFICATION ::=
-- [[not] overriding]
-- procedure DEFINING_PROGRAM_UNIT_NAME PARAMETER_PROFILE
-- | [[not] overriding]
-- function DEFINING_DESIGNATOR PARAMETER_AND_RESULT_PROFILE
-- Note: there are no separate nodes for the profiles, instead the
-- information appears directly in the following nodes.
-- N_Function_Specification
-- Sloc points to FUNCTION
-- Defining_Unit_Name (the designator)
-- Parameter_Specifications (set to No_List if no formal part)
-- Null_Exclusion_Present
-- Result_Definition for result subtype
-- Generic_Parent
-- Must_Override set if overriding indicator present
-- Must_Not_Override set if not_overriding indicator present
-- N_Procedure_Specification
-- Sloc points to PROCEDURE
-- Defining_Unit_Name
-- Null_Statement NULL statement for body, if Null_Present
-- Parameter_Specifications (set to No_List if no formal part)
-- Generic_Parent
-- Null_Present set for null procedure case (Ada 2005 feature)
-- Must_Override set if overriding indicator present
-- Must_Not_Override set if not_overriding indicator present
-- Note: overriding indicator is an Ada 2005 feature
---------------------
-- 6.1 Designator --
---------------------
-- DESIGNATOR ::=
-- [PARENT_UNIT_NAME .] IDENTIFIER | OPERATOR_SYMBOL
-- Designators that are simply identifiers or operator symbols appear
-- directly in the tree in this form. The following node is used only
-- in the case where the designator has a parent unit name component.
-- N_Designator
-- Sloc points to period
-- Name holds the parent unit name
-- Identifier
-- Note: Name is always non-Empty, since this node is only used for the
-- case where a parent library unit package name is present.
-- Note that the identifier can also be an operator symbol here
------------------------------
-- 6.1 Defining Designator --
------------------------------
-- DEFINING_DESIGNATOR ::=
-- DEFINING_PROGRAM_UNIT_NAME | DEFINING_OPERATOR_SYMBOL
-------------------------------------
-- 6.1 Defining Program Unit Name --
-------------------------------------
-- DEFINING_PROGRAM_UNIT_NAME ::=
-- [PARENT_UNIT_NAME .] DEFINING_IDENTIFIER
-- The parent unit name is present only in the case of a child unit name
-- (permissible only for Ada 95 for a library level unit, i.e. a unit
-- at scope level one). If no such name is present, the defining program
-- unit name is represented simply as the defining identifier. In the
-- child unit case, the following node is used to represent the child
-- unit name.
-- N_Defining_Program_Unit_Name
-- Sloc points to period
-- Name holds the parent unit name
-- Defining_Identifier
-- Note: Name is always non-Empty, since this node is only used for the
-- case where a parent unit name is present.
--------------------------
-- 6.1 Operator Symbol --
--------------------------
-- OPERATOR_SYMBOL ::= STRING_LITERAL
-- Note: the fields of the N_Operator_Symbol node are laid out to match
-- the corresponding fields of an N_Character_Literal node. This allows
-- easy conversion of the operator symbol node into a character literal
-- node in the case where a string constant of the form of an operator
-- symbol is scanned out as such, but turns out semantically to be a
-- string literal that is not an operator. For details see Sinfo.CN.
-- Change_Operator_Symbol_To_String_Literal.
-- N_Operator_Symbol
-- Sloc points to literal
-- Chars contains the Name_Id for the operator symbol
-- Strval Id of string value. This is used if the operator
-- symbol turns out to be a normal string after all.
-- Entity
-- Associated_Node Note this is shared with Entity
-- Etype
-- Has_Private_View (set in generic units)
-- Note: the Strval field may be set to No_String for generated
-- operator symbols that are known not to be string literals
-- semantically.
-----------------------------------
-- 6.1 Defining Operator Symbol --
-----------------------------------
-- DEFINING_OPERATOR_SYMBOL ::= OPERATOR_SYMBOL
-- A defining operator symbol is an entity, which has additional
-- fields depending on the setting of the Ekind field. These
-- additional fields are defined (and access subprograms declared)
-- in package Einfo.
-- Note: N_Defining_Operator_Symbol is an extended node whose fields
-- are deliberately laid out to match the layout of fields in an
-- ordinary N_Operator_Symbol node allowing for easy alteration of
-- an operator symbol node into a defining operator symbol node.
-- See Sinfo.CN.Change_Operator_Symbol_To_Defining_Operator_Symbol
-- for further details.
-- N_Defining_Operator_Symbol
-- Sloc points to literal
-- Chars contains the Name_Id for the operator symbol
-- Next_Entity
-- Scope
-- Etype
----------------------------
-- 6.1 Parameter Profile --
----------------------------
-- PARAMETER_PROFILE ::= [FORMAL_PART]
---------------------------------------
-- 6.1 Parameter and Result Profile --
---------------------------------------
-- PARAMETER_AND_RESULT_PROFILE ::=
-- [FORMAL_PART] return [NULL_EXCLUSION] SUBTYPE_MARK
-- | [FORMAL_PART] return ACCESS_DEFINITION
-- There is no explicit node in the tree for a parameter and result
-- profile. Instead the information appears directly in the parent.
----------------------
-- 6.1 Formal Part --
----------------------
-- FORMAL_PART ::=
-- (PARAMETER_SPECIFICATION {; PARAMETER_SPECIFICATION})
----------------------------------
-- 6.1 Parameter Specification --
----------------------------------
-- PARAMETER_SPECIFICATION ::=
-- DEFINING_IDENTIFIER_LIST : [ALIASED] MODE [NULL_EXCLUSION]
-- SUBTYPE_MARK [:= DEFAULT_EXPRESSION] [ASPECT_SPECIFICATIONS]
-- | DEFINING_IDENTIFIER_LIST : ACCESS_DEFINITION
-- [:= DEFAULT_EXPRESSION] [ASPECT_SPECIFICATIONS]
-- Although the syntax allows multiple identifiers in the list, the
-- semantics is as though successive specifications were given with
-- identical type definition and expression components. To simplify
-- semantic processing, the parser represents a multiple declaration
-- case as a sequence of single Specifications, using the More_Ids and
-- Prev_Ids flags to preserve the original source form as described
-- in the section on "Handling of Defining Identifier Lists".
-- ALIASED can only be present in Ada 2012 mode
-- N_Parameter_Specification
-- Sloc points to first identifier
-- Defining_Identifier
-- Aliased_Present
-- In_Present
-- Out_Present
-- Null_Exclusion_Present
-- Parameter_Type subtype mark or access definition
-- Expression (set to Empty if no default expression present)
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
-- Default_Expression
---------------
-- 6.1 Mode --
---------------
-- MODE ::= [in] | in out | out
-- There is no explicit node in the tree for the Mode. Instead the
-- In_Present and Out_Present flags are set in the parent node to
-- record the presence of keywords specifying the mode.
--------------------------
-- 6.3 Subprogram Body --
--------------------------
-- SUBPROGRAM_BODY ::=
-- SUBPROGRAM_SPECIFICATION [ASPECT_SPECIFICATIONS] is
-- DECLARATIVE_PART
-- begin
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [DESIGNATOR];
-- N_Subprogram_Body
-- Sloc points to FUNCTION or PROCEDURE
-- Specification
-- Declarations
-- Handled_Statement_Sequence
-- Activation_Chain_Entity
-- Corresponding_Spec
-- Acts_As_Spec
-- Bad_Is_Detected used only by parser
-- Do_Storage_Check
-- Has_Relative_Deadline_Pragma
-- Is_Entry_Barrier_Function
-- Is_Protected_Subprogram_Body
-- Is_Task_Body_Procedure
-- Is_Task_Master
-- Was_Attribute_Reference
-- Was_Expression_Function
-- Was_Originally_Stub
-----------------------------------
-- 6.4 Procedure Call Statement --
-----------------------------------
-- PROCEDURE_CALL_STATEMENT ::=
-- procedure_NAME; | procedure_PREFIX ACTUAL_PARAMETER_PART;
-- Note: the reason that a procedure call has expression fields is that
-- it semantically resembles an expression, e.g. overloading is allowed
-- and a type is concocted for semantic processing purposes. Certain of
-- these fields, such as Parens are not relevant, but it is easier to
-- just supply all of them together.
-- N_Procedure_Call_Statement
-- Sloc points to first token of name or prefix
-- Name stores name or prefix
-- Parameter_Associations (set to No_List if no
-- actual parameter part)
-- First_Named_Actual
-- Controlling_Argument (set to Empty if not dispatching)
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- No_Elaboration_Check
-- Is_Known_Guaranteed_ABE
-- plus fields for expression
-- If any IN parameter requires a range check, then the corresponding
-- argument expression has the Do_Range_Check flag set, and the range
-- check is done against the formal type. Note that this argument
-- expression may appear directly in the Parameter_Associations list,
-- or may be a descendant of an N_Parameter_Association node that
-- appears in this list.
------------------------
-- 6.4 Function Call --
------------------------
-- FUNCTION_CALL ::=
-- function_NAME | function_PREFIX ACTUAL_PARAMETER_PART
-- Note: the parser may generate an indexed component node or simply
-- a name node instead of a function call node. The semantic pass must
-- correct this misidentification.
-- N_Function_Call
-- Sloc points to first token of name or prefix
-- Name stores name or prefix
-- Parameter_Associations (set to No_List if no
-- actual parameter part)
-- First_Named_Actual
-- Controlling_Argument (set to Empty if not dispatching)
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- No_Elaboration_Check
-- Is_Expanded_Build_In_Place_Call
-- No_Side_Effect_Removal
-- Is_Known_Guaranteed_ABE
-- plus fields for expression
--------------------------------
-- 6.4 Actual Parameter Part --
--------------------------------
-- ACTUAL_PARAMETER_PART ::=
-- (PARAMETER_ASSOCIATION {,PARAMETER_ASSOCIATION})
--------------------------------
-- 6.4 Parameter Association --
--------------------------------
-- PARAMETER_ASSOCIATION ::=
-- [formal_parameter_SELECTOR_NAME =>] EXPLICIT_ACTUAL_PARAMETER
-- Note: the N_Parameter_Association node is built only if a formal
-- parameter selector name is present, otherwise the parameter
-- association appears in the tree simply as the node for the
-- explicit actual parameter.
-- N_Parameter_Association
-- Sloc points to formal parameter
-- Selector_Name (always non-Empty)
-- Explicit_Actual_Parameter
-- Next_Named_Actual
-- Is_Accessibility_Actual
---------------------------
-- 6.4 Actual Parameter --
---------------------------
-- EXPLICIT_ACTUAL_PARAMETER ::=
-- EXPRESSION | variable_NAME | REDUCTION_EXPRESSION_PARAMETER
---------------------------
-- 6.5 Return Statement --
---------------------------
-- SIMPLE_RETURN_STATEMENT ::= return [EXPRESSION];
-- EXTENDED_RETURN_STATEMENT ::=
-- return DEFINING_IDENTIFIER : [aliased] RETURN_SUBTYPE_INDICATION
-- [:= EXPRESSION] [do
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end return];
-- RETURN_SUBTYPE_INDICATION ::= SUBTYPE_INDICATION | ACCESS_DEFINITION
-- The term "return statement" is defined in 6.5 to mean either a
-- SIMPLE_RETURN_STATEMENT or an EXTENDED_RETURN_STATEMENT. We avoid
-- the use of this term, since it used to mean someting else in earlier
-- versions of Ada.
-- N_Simple_Return_Statement
-- Sloc points to RETURN
-- Return_Statement_Entity
-- Expression (set to Empty if no expression present)
-- Storage_Pool
-- Procedure_To_Call
-- By_Ref
-- Comes_From_Extended_Return_Statement
-- Note: Return_Statement_Entity points to an E_Return_Statement
-- If a range check is required, then Do_Range_Check is set on the
-- Expression. The check is against the return subtype of the function.
-- N_Extended_Return_Statement
-- Sloc points to RETURN
-- Return_Statement_Entity
-- Return_Object_Declarations
-- Handled_Statement_Sequence (set to Empty if not present)
-- Storage_Pool
-- Procedure_To_Call
-- By_Ref
-- Note: Return_Statement_Entity points to an E_Return_Statement.
-- Note that Return_Object_Declarations is a list containing the
-- N_Object_Declaration -- see comment on this field above.
-- The declared object will have Is_Return_Object = True.
-- There is no such syntactic category as return_object_declaration
-- in the RM. Return_Object_Declarations represents this portion of
-- the syntax for EXTENDED_RETURN_STATEMENT:
-- DEFINING_IDENTIFIER : [aliased] RETURN_SUBTYPE_INDICATION
-- [:= EXPRESSION]
-- There are two entities associated with an extended_return_statement:
-- the Return_Statement_Entity represents the statement itself,
-- and the Defining_Identifier of the Object_Declaration in
-- Return_Object_Declarations represents the object being
-- returned. N_Simple_Return_Statement has only the former.
------------------------------
-- 6.8 Expression Function --
------------------------------
-- EXPRESSION_FUNCTION ::=
-- FUNCTION SPECIFICATION IS (EXPRESSION)
-- [ASPECT_SPECIFICATIONS];
-- N_Expression_Function
-- Sloc points to FUNCTION
-- Specification
-- Expression
-- Corresponding_Spec
------------------------------
-- 7.1 Package Declaration --
------------------------------
-- PACKAGE_DECLARATION ::=
-- PACKAGE_SPECIFICATION;
-- Note: the activation chain entity for a package spec is used for
-- all tasks declared in the package spec, or in the package body.
-- N_Package_Declaration
-- Sloc points to PACKAGE
-- Specification
-- Corresponding_Body
-- Parent_Spec
-- Activation_Chain_Entity
--------------------------------
-- 7.1 Package Specification --
--------------------------------
-- PACKAGE_SPECIFICATION ::=
-- package DEFINING_PROGRAM_UNIT_NAME
-- [ASPECT_SPECIFICATIONS]
-- is
-- {BASIC_DECLARATIVE_ITEM}
-- [private
-- {BASIC_DECLARATIVE_ITEM}]
-- end [[PARENT_UNIT_NAME .] IDENTIFIER]
-- N_Package_Specification
-- Sloc points to PACKAGE
-- Defining_Unit_Name
-- Visible_Declarations
-- Private_Declarations (set to No_List if no private
-- part present)
-- End_Label
-- Generic_Parent
-- Limited_View_Installed
-----------------------
-- 7.1 Package Body --
-----------------------
-- PACKAGE_BODY ::=
-- package body DEFINING_PROGRAM_UNIT_NAME
-- [ASPECT_SPECIFICATIONS]
-- is
-- DECLARATIVE_PART
-- [begin
-- HANDLED_SEQUENCE_OF_STATEMENTS]
-- end [[PARENT_UNIT_NAME .] IDENTIFIER];
-- N_Package_Body
-- Sloc points to PACKAGE
-- Defining_Unit_Name
-- Declarations
-- Handled_Statement_Sequence (set to Empty if no HSS present)
-- Corresponding_Spec
-- Was_Originally_Stub
-- Note: if a source level package does not contain a handled sequence
-- of statements, then the parser supplies a dummy one with a null
-- sequence of statements. Comes_From_Source will be False in this
-- constructed sequence. The reason we need this is for the End_Label
-- field in the HSS.
-----------------------------------
-- 7.4 Private Type Declaration --
-----------------------------------
-- PRIVATE_TYPE_DECLARATION ::=
-- type DEFINING_IDENTIFIER [DISCRIMINANT_PART]
-- is [[abstract] tagged] [limited] private
-- [ASPECT_SPECIFICATIONS];
-- Note: TAGGED is not permitted in Ada 83 mode
-- N_Private_Type_Declaration
-- Sloc points to TYPE
-- Defining_Identifier
-- Discriminant_Specifications (set to No_List if no
-- discriminant part)
-- Unknown_Discriminants_Present set if (<>) discriminant
-- Abstract_Present
-- Tagged_Present
-- Limited_Present
----------------------------------------
-- 7.4 Private Extension Declaration --
----------------------------------------
-- PRIVATE_EXTENSION_DECLARATION ::=
-- type DEFINING_IDENTIFIER [DISCRIMINANT_PART] is
-- [abstract] [limited | synchronized]
-- new ancestor_SUBTYPE_INDICATION [and INTERFACE_LIST]
-- with private [ASPECT_SPECIFICATIONS];
-- Note: LIMITED, and private extension declarations are not allowed
-- in Ada 83 mode.
-- N_Private_Extension_Declaration
-- Sloc points to TYPE
-- Defining_Identifier
-- Uninitialized_Variable
-- Discriminant_Specifications (set to No_List if no
-- discriminant part)
-- Unknown_Discriminants_Present set if (<>) discriminant
-- Abstract_Present
-- Limited_Present
-- Synchronized_Present
-- Subtype_Indication
-- Interface_List (set to No_List if none)
---------------------
-- 8.4 Use Clause --
---------------------
-- USE_CLAUSE ::= USE_PACKAGE_CLAUSE | USE_TYPE_CLAUSE
-----------------------------
-- 8.4 Use Package Clause --
-----------------------------
-- USE_PACKAGE_CLAUSE ::= use package_NAME {, package_NAME};
-- N_Use_Package_Clause
-- Sloc points to USE
-- Prev_Use_Clause
-- Name
-- Next_Use_Clause
-- Associated_Node
-- Hidden_By_Use_Clause
-- Is_Effective_Use_Clause
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
--------------------------
-- 8.4 Use Type Clause --
--------------------------
-- USE_TYPE_CLAUSE ::= use [ALL] type SUBTYPE_MARK {, SUBTYPE_MARK};
-- Note: use type clause is not permitted in Ada 83 mode
-- Note: the ALL keyword can appear only in Ada 2012 mode
-- N_Use_Type_Clause
-- Sloc points to USE
-- Prev_Use_Clause
-- Used_Operations
-- Next_Use_Clause
-- Subtype_Mark
-- Hidden_By_Use_Clause
-- Is_Effective_Use_Clause
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
-- All_Present
-------------------------------
-- 8.5 Renaming Declaration --
-------------------------------
-- RENAMING_DECLARATION ::=
-- OBJECT_RENAMING_DECLARATION
-- | EXCEPTION_RENAMING_DECLARATION
-- | PACKAGE_RENAMING_DECLARATION
-- | SUBPROGRAM_RENAMING_DECLARATION
-- | GENERIC_RENAMING_DECLARATION
--------------------------------------
-- 8.5 Object Renaming Declaration --
--------------------------------------
-- OBJECT_RENAMING_DECLARATION ::=
-- DEFINING_IDENTIFIER :
-- [NULL_EXCLUSION] SUBTYPE_MARK renames object_NAME
-- [ASPECT_SPECIFICATIONS];
-- | DEFINING_IDENTIFIER :
-- ACCESS_DEFINITION renames object_NAME
-- [ASPECT_SPECIFICATIONS];
-- Note: Access_Definition is an optional field that gives support to
-- Ada 2005 (AI-230). The parser generates nodes that have either the
-- Subtype_Indication field or else the Access_Definition field.
-- N_Object_Renaming_Declaration
-- Sloc points to first identifier
-- Defining_Identifier
-- Null_Exclusion_Present (set to False if not present)
-- Subtype_Mark (set to Empty if not present)
-- Access_Definition (set to Empty if not present)
-- Name
-- Corresponding_Generic_Association
-----------------------------------------
-- 8.5 Exception Renaming Declaration --
-----------------------------------------
-- EXCEPTION_RENAMING_DECLARATION ::=
-- DEFINING_IDENTIFIER : exception renames exception_NAME
-- [ASPECT_SPECIFICATIONS];
-- N_Exception_Renaming_Declaration
-- Sloc points to first identifier
-- Defining_Identifier
-- Name
---------------------------------------
-- 8.5 Package Renaming Declaration --
---------------------------------------
-- PACKAGE_RENAMING_DECLARATION ::=
-- package DEFINING_PROGRAM_UNIT_NAME renames package_NAME
-- [ASPECT_SPECIFICATIONS];
-- N_Package_Renaming_Declaration
-- Sloc points to PACKAGE
-- Defining_Unit_Name
-- Name
-- Parent_Spec
------------------------------------------
-- 8.5 Subprogram Renaming Declaration --
------------------------------------------
-- SUBPROGRAM_RENAMING_DECLARATION ::=
-- SUBPROGRAM_SPECIFICATION renames callable_entity_NAME
-- [ASPECT_SPECIFICATIONS];
-- N_Subprogram_Renaming_Declaration
-- Sloc points to RENAMES
-- Specification
-- Name
-- Parent_Spec
-- Corresponding_Spec
-- Corresponding_Formal_Spec
-- From_Default
-----------------------------------------
-- 8.5.5 Generic Renaming Declaration --
-----------------------------------------
-- GENERIC_RENAMING_DECLARATION ::=
-- generic package DEFINING_PROGRAM_UNIT_NAME
-- renames generic_package_NAME
-- [ASPECT_SPECIFICATIONS];
-- | generic procedure DEFINING_PROGRAM_UNIT_NAME
-- renames generic_procedure_NAME
-- [ASPECT_SPECIFICATIONS];
-- | generic function DEFINING_PROGRAM_UNIT_NAME
-- renames generic_function_NAME
-- [ASPECT_SPECIFICATIONS];
-- N_Generic_Package_Renaming_Declaration
-- Sloc points to GENERIC
-- Defining_Unit_Name
-- Name
-- Parent_Spec
-- N_Generic_Procedure_Renaming_Declaration
-- Sloc points to GENERIC
-- Defining_Unit_Name
-- Name
-- Parent_Spec
-- N_Generic_Function_Renaming_Declaration
-- Sloc points to GENERIC
-- Defining_Unit_Name
-- Name
-- Parent_Spec
--------------------------------
-- 9.1 Task Type Declaration --
--------------------------------
-- TASK_TYPE_DECLARATION ::=
-- task type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART]
-- [ASPECT_SPECIFICATIONS]
-- [is [new INTERFACE_LIST with] TASK_DEFINITION];
-- N_Task_Type_Declaration
-- Sloc points to TASK
-- Defining_Identifier
-- Discriminant_Specifications (set to No_List if no
-- discriminant part)
-- Interface_List (set to No_List if none)
-- Task_Definition (set to Empty if not present)
-- Corresponding_Body
----------------------------------
-- 9.1 Single Task Declaration --
----------------------------------
-- SINGLE_TASK_DECLARATION ::=
-- task DEFINING_IDENTIFIER
-- [ASPECT_SPECIFICATIONS]
-- [is [new INTERFACE_LIST with] TASK_DEFINITION];
-- N_Single_Task_Declaration
-- Sloc points to TASK
-- Defining_Identifier
-- Interface_List (set to No_List if none)
-- Task_Definition (set to Empty if not present)
--------------------------
-- 9.1 Task Definition --
--------------------------
-- TASK_DEFINITION ::=
-- {TASK_ITEM}
-- [private
-- {TASK_ITEM}]
-- end [task_IDENTIFIER]
-- Note: as a result of semantic analysis, the list of task items can
-- include implicit type declarations resulting from entry families.
-- N_Task_Definition
-- Sloc points to first token of task definition
-- Visible_Declarations
-- Private_Declarations (set to No_List if no private part)
-- End_Label
-- Has_Storage_Size_Pragma
-- Has_Relative_Deadline_Pragma
--------------------
-- 9.1 Task Item --
--------------------
-- TASK_ITEM ::= ENTRY_DECLARATION | REPRESENTATION_CLAUSE
--------------------
-- 9.1 Task Body --
--------------------
-- TASK_BODY ::=
-- task body task_DEFINING_IDENTIFIER
-- [ASPECT_SPECIFICATIONS]
-- is
-- DECLARATIVE_PART
-- begin
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [task_IDENTIFIER];
-- Gigi restriction: This node never appears
-- N_Task_Body
-- Sloc points to TASK
-- Defining_Identifier
-- Declarations
-- Handled_Statement_Sequence
-- Is_Task_Master
-- Activation_Chain_Entity
-- Corresponding_Spec
-- Was_Originally_Stub
-------------------------------------
-- 9.4 Protected Type Declaration --
-------------------------------------
-- PROTECTED_TYPE_DECLARATION ::=
-- protected type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART]
-- [ASPECT_SPECIFICATIONS]
-- is [new INTERFACE_LIST with] PROTECTED_DEFINITION;
-- Note: protected type declarations are not permitted in Ada 83 mode
-- N_Protected_Type_Declaration
-- Sloc points to PROTECTED
-- Defining_Identifier
-- Discriminant_Specifications (set to No_List if no
-- discriminant part)
-- Interface_List (set to No_List if none)
-- Protected_Definition
-- Corresponding_Body
---------------------------------------
-- 9.4 Single Protected Declaration --
---------------------------------------
-- SINGLE_PROTECTED_DECLARATION ::=
-- protected DEFINING_IDENTIFIER
-- [ASPECT_SPECIFICATIONS]
-- is [new INTERFACE_LIST with] PROTECTED_DEFINITION;
-- Note: single protected declarations are not allowed in Ada 83 mode
-- N_Single_Protected_Declaration
-- Sloc points to PROTECTED
-- Defining_Identifier
-- Interface_List (set to No_List if none)
-- Protected_Definition
-------------------------------
-- 9.4 Protected Definition --
-------------------------------
-- PROTECTED_DEFINITION ::=
-- {PROTECTED_OPERATION_DECLARATION}
-- [private
-- {PROTECTED_ELEMENT_DECLARATION}]
-- end [protected_IDENTIFIER]
-- N_Protected_Definition
-- Sloc points to first token of protected definition
-- Visible_Declarations
-- Private_Declarations (set to No_List if no private part)
-- End_Label
------------------------------------------
-- 9.4 Protected Operation Declaration --
------------------------------------------
-- PROTECTED_OPERATION_DECLARATION ::=
-- SUBPROGRAM_DECLARATION
-- | ENTRY_DECLARATION
-- | REPRESENTATION_CLAUSE
----------------------------------------
-- 9.4 Protected Element Declaration --
----------------------------------------
-- PROTECTED_ELEMENT_DECLARATION ::=
-- PROTECTED_OPERATION_DECLARATION | COMPONENT_DECLARATION
-------------------------
-- 9.4 Protected Body --
-------------------------
-- PROTECTED_BODY ::=
-- protected body DEFINING_IDENTIFIER
-- [ASPECT_SPECIFICATIONS];
-- is
-- {PROTECTED_OPERATION_ITEM}
-- end [protected_IDENTIFIER];
-- Note: protected bodies are not allowed in Ada 83 mode
-- Gigi restriction: This node never appears
-- N_Protected_Body
-- Sloc points to PROTECTED
-- Defining_Identifier
-- Declarations protected operation items (and pragmas)
-- End_Label
-- Corresponding_Spec
-- Was_Originally_Stub
-----------------------------------
-- 9.4 Protected Operation Item --
-----------------------------------
-- PROTECTED_OPERATION_ITEM ::=
-- SUBPROGRAM_DECLARATION
-- | SUBPROGRAM_BODY
-- | ENTRY_BODY
-- | REPRESENTATION_CLAUSE
------------------------------
-- 9.5.2 Entry Declaration --
------------------------------
-- ENTRY_DECLARATION ::=
-- [[not] overriding]
-- entry DEFINING_IDENTIFIER
-- [(DISCRETE_SUBTYPE_DEFINITION)] PARAMETER_PROFILE
-- [ASPECT_SPECIFICATIONS];
-- N_Entry_Declaration
-- Sloc points to ENTRY
-- Defining_Identifier
-- Discrete_Subtype_Definition (set to Empty if not present)
-- Parameter_Specifications (set to No_List if no formal part)
-- Corresponding_Body
-- Must_Override set if overriding indicator present
-- Must_Not_Override set if not_overriding indicator present
-- Note: overriding indicator is an Ada 2005 feature
-----------------------------
-- 9.5.2 Accept statement --
-----------------------------
-- ACCEPT_STATEMENT ::=
-- accept entry_DIRECT_NAME
-- [(ENTRY_INDEX)] PARAMETER_PROFILE [do
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [entry_IDENTIFIER]];
-- Gigi restriction: This node never appears
-- Note: there are no explicit declarations allowed in an accept
-- statement. However, the implicit declarations for any statement
-- identifiers (labels and block/loop identifiers) are declarations
-- that belong logically to the accept statement, and that is why
-- there is a Declarations field in this node.
-- N_Accept_Statement
-- Sloc points to ACCEPT
-- Entry_Direct_Name
-- Entry_Index (set to Empty if not present)
-- Parameter_Specifications (set to No_List if no formal part)
-- Handled_Statement_Sequence
-- Declarations (set to No_List if no declarations)
------------------------
-- 9.5.2 Entry Index --
------------------------
-- ENTRY_INDEX ::= EXPRESSION
-----------------------
-- 9.5.2 Entry Body --
-----------------------
-- ENTRY_BODY ::=
-- entry DEFINING_IDENTIFIER ENTRY_BODY_FORMAL_PART ENTRY_BARRIER is
-- DECLARATIVE_PART
-- begin
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [entry_IDENTIFIER];
-- ENTRY_BARRIER ::= when CONDITION
-- Note: we store the CONDITION of the ENTRY_BARRIER in the node for
-- the ENTRY_BODY_FORMAL_PART to avoid the N_Entry_Body node getting
-- too full (it would otherwise have too many fields)
-- Gigi restriction: This node never appears
-- N_Entry_Body
-- Sloc points to ENTRY
-- Defining_Identifier
-- Entry_Body_Formal_Part
-- Declarations
-- Handled_Statement_Sequence
-- Activation_Chain_Entity
-----------------------------------
-- 9.5.2 Entry Body Formal Part --
-----------------------------------
-- ENTRY_BODY_FORMAL_PART ::=
-- [(ENTRY_INDEX_SPECIFICATION)] PARAMETER_PROFILE
-- Note that an entry body formal part node is present even if it is
-- empty. This reflects the grammar, in which it is the components of
-- the entry body formal part that are optional, not the entry body
-- formal part itself. Also this means that the barrier condition
-- always has somewhere to be stored.
-- Gigi restriction: This node never appears
-- N_Entry_Body_Formal_Part
-- Sloc points to first token
-- Entry_Index_Specification (set to Empty if not present)
-- Parameter_Specifications (set to No_List if no formal part)
-- Condition from entry barrier of entry body
--------------------------
-- 9.5.2 Entry Barrier --
--------------------------
-- ENTRY_BARRIER ::= when CONDITION
--------------------------------------
-- 9.5.2 Entry Index Specification --
--------------------------------------
-- ENTRY_INDEX_SPECIFICATION ::=
-- for DEFINING_IDENTIFIER in DISCRETE_SUBTYPE_DEFINITION
-- Gigi restriction: This node never appears
-- N_Entry_Index_Specification
-- Sloc points to FOR
-- Defining_Identifier
-- Discrete_Subtype_Definition
---------------------------------
-- 9.5.3 Entry Call Statement --
---------------------------------
-- ENTRY_CALL_STATEMENT ::= entry_NAME [ACTUAL_PARAMETER_PART];
-- The parser may generate a procedure call for this construct. The
-- semantic pass must correct this misidentification where needed.
-- Gigi restriction: This node never appears
-- N_Entry_Call_Statement
-- Sloc points to first token of name
-- Name
-- Parameter_Associations (set to No_List if no
-- actual parameter part)
-- First_Named_Actual
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
------------------------------
-- 9.5.4 Requeue Statement --
------------------------------
-- REQUEUE_STATEMENT ::= requeue entry_NAME [with abort];
-- Note: requeue statements are not permitted in Ada 83 mode
-- Gigi restriction: This node never appears
-- N_Requeue_Statement
-- Sloc points to REQUEUE
-- Name
-- Abort_Present
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
--------------------------
-- 9.6 Delay Statement --
--------------------------
-- DELAY_STATEMENT ::=
-- DELAY_UNTIL_STATEMENT
-- | DELAY_RELATIVE_STATEMENT
--------------------------------
-- 9.6 Delay Until Statement --
--------------------------------
-- DELAY_UNTIL_STATEMENT ::= delay until delay_EXPRESSION;
-- Note: delay until statements are not permitted in Ada 83 mode
-- Gigi restriction: This node never appears
-- N_Delay_Until_Statement
-- Sloc points to DELAY
-- Expression
-----------------------------------
-- 9.6 Delay Relative Statement --
-----------------------------------
-- DELAY_RELATIVE_STATEMENT ::= delay delay_EXPRESSION;
-- Gigi restriction: This node never appears
-- N_Delay_Relative_Statement
-- Sloc points to DELAY
-- Expression
---------------------------
-- 9.7 Select Statement --
---------------------------
-- SELECT_STATEMENT ::=
-- SELECTIVE_ACCEPT
-- | TIMED_ENTRY_CALL
-- | CONDITIONAL_ENTRY_CALL
-- | ASYNCHRONOUS_SELECT
-----------------------------
-- 9.7.1 Selective Accept --
-----------------------------
-- SELECTIVE_ACCEPT ::=
-- select
-- [GUARD]
-- SELECT_ALTERNATIVE
-- {or
-- [GUARD]
-- SELECT_ALTERNATIVE}
-- [else
-- SEQUENCE_OF_STATEMENTS]
-- end select;
-- Gigi restriction: This node never appears
-- Note: the guard expression, if present, appears in the node for
-- the select alternative.
-- N_Selective_Accept
-- Sloc points to SELECT
-- Select_Alternatives
-- Else_Statements (set to No_List if no else part)
------------------
-- 9.7.1 Guard --
------------------
-- GUARD ::= when CONDITION =>
-- As noted above, the CONDITION that is part of a GUARD is included
-- in the node for the select alternative for convenience.
-------------------------------
-- 9.7.1 Select Alternative --
-------------------------------
-- SELECT_ALTERNATIVE ::=
-- ACCEPT_ALTERNATIVE
-- | DELAY_ALTERNATIVE
-- | TERMINATE_ALTERNATIVE
-------------------------------
-- 9.7.1 Accept Alternative --
-------------------------------
-- ACCEPT_ALTERNATIVE ::=
-- ACCEPT_STATEMENT [SEQUENCE_OF_STATEMENTS]
-- Gigi restriction: This node never appears
-- N_Accept_Alternative
-- Sloc points to ACCEPT
-- Accept_Statement
-- Condition from the guard (set to Empty if no guard present)
-- Statements (set to Empty_List if no statements)
-- Pragmas_Before pragmas before alt (set to No_List if none)
-- Accept_Handler_Records
------------------------------
-- 9.7.1 Delay Alternative --
------------------------------
-- DELAY_ALTERNATIVE ::=
-- DELAY_STATEMENT [SEQUENCE_OF_STATEMENTS]
-- Gigi restriction: This node never appears
-- N_Delay_Alternative
-- Sloc points to DELAY
-- Delay_Statement
-- Condition from the guard (set to Empty if no guard present)
-- Statements (set to Empty_List if no statements)
-- Pragmas_Before pragmas before alt (set to No_List if none)
----------------------------------
-- 9.7.1 Terminate Alternative --
----------------------------------
-- TERMINATE_ALTERNATIVE ::= terminate;
-- Gigi restriction: This node never appears
-- N_Terminate_Alternative
-- Sloc points to TERMINATE
-- Condition from the guard (set to Empty if no guard present)
-- Pragmas_Before pragmas before alt (set to No_List if none)
-- Pragmas_After pragmas after alt (set to No_List if none)
-----------------------------
-- 9.7.2 Timed Entry Call --
-----------------------------
-- TIMED_ENTRY_CALL ::=
-- select
-- ENTRY_CALL_ALTERNATIVE
-- or
-- DELAY_ALTERNATIVE
-- end select;
-- Gigi restriction: This node never appears
-- N_Timed_Entry_Call
-- Sloc points to SELECT
-- Entry_Call_Alternative
-- Delay_Alternative
-----------------------------------
-- 9.7.2 Entry Call Alternative --
-----------------------------------
-- ENTRY_CALL_ALTERNATIVE ::=
-- PROCEDURE_OR_ENTRY_CALL [SEQUENCE_OF_STATEMENTS]
-- PROCEDURE_OR_ENTRY_CALL ::=
-- PROCEDURE_CALL_STATEMENT | ENTRY_CALL_STATEMENT
-- Gigi restriction: This node never appears
-- N_Entry_Call_Alternative
-- Sloc points to first token of entry call statement
-- Entry_Call_Statement
-- Statements (set to Empty_List if no statements)
-- Pragmas_Before pragmas before alt (set to No_List if none)
-----------------------------------
-- 9.7.3 Conditional Entry Call --
-----------------------------------
-- CONDITIONAL_ENTRY_CALL ::=
-- select
-- ENTRY_CALL_ALTERNATIVE
-- else
-- SEQUENCE_OF_STATEMENTS
-- end select;
-- Gigi restriction: This node never appears
-- N_Conditional_Entry_Call
-- Sloc points to SELECT
-- Entry_Call_Alternative
-- Else_Statements
--------------------------------
-- 9.7.4 Asynchronous Select --
--------------------------------
-- ASYNCHRONOUS_SELECT ::=
-- select
-- TRIGGERING_ALTERNATIVE
-- then abort
-- ABORTABLE_PART
-- end select;
-- Note: asynchronous select is not permitted in Ada 83 mode
-- Gigi restriction: This node never appears
-- N_Asynchronous_Select
-- Sloc points to SELECT
-- Triggering_Alternative
-- Abortable_Part
-----------------------------------
-- 9.7.4 Triggering Alternative --
-----------------------------------
-- TRIGGERING_ALTERNATIVE ::=
-- TRIGGERING_STATEMENT [SEQUENCE_OF_STATEMENTS]
-- Gigi restriction: This node never appears
-- N_Triggering_Alternative
-- Sloc points to first token of triggering statement
-- Triggering_Statement
-- Statements (set to Empty_List if no statements)
-- Pragmas_Before pragmas before alt (set to No_List if none)
---------------------------------
-- 9.7.4 Triggering Statement --
---------------------------------
-- TRIGGERING_STATEMENT ::= PROCEDURE_OR_ENTRY_CALL | DELAY_STATEMENT
---------------------------
-- 9.7.4 Abortable Part --
---------------------------
-- ABORTABLE_PART ::= SEQUENCE_OF_STATEMENTS
-- Gigi restriction: This node never appears
-- N_Abortable_Part
-- Sloc points to ABORT
-- Statements
--------------------------
-- 9.8 Abort Statement --
--------------------------
-- ABORT_STATEMENT ::= abort task_NAME {, task_NAME};
-- Gigi restriction: This node never appears
-- N_Abort_Statement
-- Sloc points to ABORT
-- Names
-------------------------
-- 10.1.1 Compilation --
-------------------------
-- COMPILATION ::= {COMPILATION_UNIT}
-- There is no explicit node in the tree for a compilation, since in
-- general the compiler is processing only a single compilation unit
-- at a time. It is possible to parse multiple units in syntax check
-- only mode, but the trees are discarded in that case.
------------------------------
-- 10.1.1 Compilation Unit --
------------------------------
-- COMPILATION_UNIT ::=
-- CONTEXT_CLAUSE LIBRARY_ITEM
-- | CONTEXT_CLAUSE SUBUNIT
-- The N_Compilation_Unit node itself represents the above syntax.
-- However, there are two additional items not reflected in the above
-- syntax. First we have the global declarations that are added by the
-- code generator. These are outer level declarations (so they cannot
-- be represented as being inside the units). An example is the wrapper
-- subprograms that are created to do ABE checking. As always a list of
-- declarations can contain actions as well (i.e. statements), and such
-- statements are executed as part of the elaboration of the unit. Note
-- that all such declarations are elaborated before the library unit.
-- Similarly, certain actions need to be elaborated at the completion
-- of elaboration of the library unit (notably the statement that sets
-- the Boolean flag indicating that elaboration is complete).
-- The third item not reflected in the syntax is pragmas that appear
-- after the compilation unit. As always pragmas are a problem since
-- they are not part of the formal syntax, but can be stuck into the
-- source following a set of ad hoc rules, and we have to find an ad
-- hoc way of sticking them into the tree. For pragmas that appear
-- before the library unit, we just consider them to be part of the
-- context clause, and pragmas can appear in the Context_Items list
-- of the compilation unit. However, pragmas can also appear after
-- the library item.
-- To deal with all these problems, we create an auxiliary node for
-- a compilation unit, referenced from the N_Compilation_Unit node,
-- that contains these items.
-- N_Compilation_Unit
-- Sloc points to first token of defining unit name
-- Context_Items context items and pragmas preceding unit
-- Private_Present set if library unit has private keyword
-- Unit library item or subunit
-- Aux_Decls_Node points to the N_Compilation_Unit_Aux node
-- First_Inlined_Subprogram
-- Library_Unit corresponding/parent spec/body
-- Save_Invocation_Graph_Of_Body
-- Acts_As_Spec flag for subprogram body with no spec
-- Body_Required set for spec if body is required
-- Has_Pragma_Suppress_All
-- Context_Pending
-- Has_No_Elaboration_Code
-- N_Compilation_Unit_Aux
-- Sloc is a copy of the Sloc from the N_Compilation_Unit node
-- Declarations (set to No_List if no global declarations)
-- Actions (set to No_List if no actions)
-- Pragmas_After pragmas after unit (set to No_List if none)
-- Config_Pragmas config pragmas (set to Empty_List if none)
-- Default_Storage_Pool
--------------------------
-- 10.1.1 Library Item --
--------------------------
-- LIBRARY_ITEM ::=
-- [private] LIBRARY_UNIT_DECLARATION
-- | LIBRARY_UNIT_BODY
-- | [private] LIBRARY_UNIT_RENAMING_DECLARATION
-- Note: PRIVATE is not allowed in Ada 83 mode
-- There is no explicit node in the tree for library item, instead
-- the declaration or body, and the flag for private if present,
-- appear in the N_Compilation_Unit node.
--------------------------------------
-- 10.1.1 Library Unit Declaration --
--------------------------------------
-- LIBRARY_UNIT_DECLARATION ::=
-- SUBPROGRAM_DECLARATION | PACKAGE_DECLARATION
-- | GENERIC_DECLARATION | GENERIC_INSTANTIATION
-----------------------------------------------
-- 10.1.1 Library Unit Renaming Declaration --
-----------------------------------------------
-- LIBRARY_UNIT_RENAMING_DECLARATION ::=
-- PACKAGE_RENAMING_DECLARATION
-- | GENERIC_RENAMING_DECLARATION
-- | SUBPROGRAM_RENAMING_DECLARATION
-------------------------------
-- 10.1.1 Library unit body --
-------------------------------
-- LIBRARY_UNIT_BODY ::= SUBPROGRAM_BODY | PACKAGE_BODY
------------------------------
-- 10.1.1 Parent Unit Name --
------------------------------
-- PARENT_UNIT_NAME ::= NAME
----------------------------
-- 10.1.2 Context clause --
----------------------------
-- CONTEXT_CLAUSE ::= {CONTEXT_ITEM}
-- The context clause can include pragmas, and any pragmas that appear
-- before the context clause proper (i.e. all configuration pragmas,
-- also appear at the front of this list).
--------------------------
-- 10.1.2 Context_Item --
--------------------------
-- CONTEXT_ITEM ::= WITH_CLAUSE | USE_CLAUSE | WITH_TYPE_CLAUSE
-------------------------
-- 10.1.2 With clause --
-------------------------
-- WITH_CLAUSE ::=
-- with library_unit_NAME {,library_unit_NAME};
-- A separate With clause is built for each name, so that we have
-- a Corresponding_Spec field for each with'ed spec. The flags
-- First_Name and Last_Name are used to reconstruct the exact
-- source form. When a list of names appears in one with clause,
-- the first name in the list has First_Name set, and the last
-- has Last_Name set. If the with clause has only one name, then
-- both of the flags First_Name and Last_Name are set in this name.
-- Note: in the case of implicit with's that are installed by the
-- Rtsfind routine, Implicit_With is set, and the Sloc is typically
-- set to Standard_Location, but it is incorrect to test the Sloc
-- to find out if a with clause is implicit, test the flag instead.
-- N_With_Clause
-- Sloc points to first token of library unit name
-- Name
-- Private_Present set if with_clause has private keyword
-- Limited_Present set if LIMITED is present
-- Next_Implicit_With
-- Library_Unit
-- Corresponding_Spec
-- First_Name (set to True if first name or only one name)
-- Last_Name (set to True if last name or only one name)
-- Context_Installed
-- Elaborate_Present
-- Elaborate_All_Present
-- Elaborate_All_Desirable
-- Elaborate_Desirable
-- Implicit_With
-- Limited_View_Installed
-- Parent_With
-- Unreferenced_In_Spec
-- No_Entities_Ref_In_Spec
-- Note: Limited_Present and Limited_View_Installed are used to support
-- the implementation of Ada 2005 (AI-50217).
-- Similarly, Private_Present is used to support the implementation of
-- Ada 2005 (AI-50262).
-- Note: if the WITH clause refers to a standard library unit, then a
-- limited with clause is changed into a normal with clause, because we
-- are not prepared to deal with limited with in the context of Rtsfind.
-- So in this case, the Limited_Present flag will be False in the final
-- tree.
----------------------
-- With_Type clause --
----------------------
-- This is a GNAT extension, used to implement mutually recursive
-- types declared in different packages.
-- Note: this is now obsolete. The functionality of this construct
-- is now implemented by the Ada 2005 limited_with_clause.
---------------------
-- 10.2 Body stub --
---------------------
-- BODY_STUB ::=
-- SUBPROGRAM_BODY_STUB
-- | PACKAGE_BODY_STUB
-- | TASK_BODY_STUB
-- | PROTECTED_BODY_STUB
----------------------------------
-- 10.1.3 Subprogram Body Stub --
----------------------------------
-- SUBPROGRAM_BODY_STUB ::=
-- SUBPROGRAM_SPECIFICATION is separate
-- [ASPECT_SPECIFICATION];
-- N_Subprogram_Body_Stub
-- Sloc points to FUNCTION or PROCEDURE
-- Specification
-- Corresponding_Spec_Of_Stub
-- Library_Unit points to the subunit
-- Corresponding_Body
-------------------------------
-- 10.1.3 Package Body Stub --
-------------------------------
-- PACKAGE_BODY_STUB ::=
-- package body DEFINING_IDENTIFIER is separate
-- [ASPECT_SPECIFICATION];
-- N_Package_Body_Stub
-- Sloc points to PACKAGE
-- Defining_Identifier
-- Corresponding_Spec_Of_Stub
-- Library_Unit points to the subunit
-- Corresponding_Body
----------------------------
-- 10.1.3 Task Body Stub --
----------------------------
-- TASK_BODY_STUB ::=
-- task body DEFINING_IDENTIFIER is separate
-- [ASPECT_SPECIFICATION];
-- N_Task_Body_Stub
-- Sloc points to TASK
-- Defining_Identifier
-- Corresponding_Spec_Of_Stub
-- Library_Unit points to the subunit
-- Corresponding_Body
---------------------------------
-- 10.1.3 Protected Body Stub --
---------------------------------
-- PROTECTED_BODY_STUB ::=
-- protected body DEFINING_IDENTIFIER is separate
-- [ASPECT_SPECIFICATION];
-- Note: protected body stubs are not allowed in Ada 83 mode
-- N_Protected_Body_Stub
-- Sloc points to PROTECTED
-- Defining_Identifier
-- Corresponding_Spec_Of_Stub
-- Library_Unit points to the subunit
-- Corresponding_Body
---------------------
-- 10.1.3 Subunit --
---------------------
-- SUBUNIT ::= separate (PARENT_UNIT_NAME) PROPER_BODY
-- N_Subunit
-- Sloc points to SEPARATE
-- Name is the name of the parent unit
-- Proper_Body is the subunit body
-- Corresponding_Stub is the stub declaration for the unit.
---------------------------------
-- 11.1 Exception Declaration --
---------------------------------
-- EXCEPTION_DECLARATION ::= DEFINING_IDENTIFIER_LIST : exception
-- [ASPECT_SPECIFICATIONS];
-- For consistency with object declarations etc., the parser converts
-- the case of multiple identifiers being declared to a series of
-- declarations in which the expression is copied, using the More_Ids
-- and Prev_Ids flags to remember the source form as described in the
-- section on "Handling of Defining Identifier Lists".
-- N_Exception_Declaration
-- Sloc points to EXCEPTION
-- Defining_Identifier
-- Expression
-- Renaming_Exception
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
------------------------------------------
-- 11.2 Handled Sequence Of Statements --
------------------------------------------
-- HANDLED_SEQUENCE_OF_STATEMENTS ::=
-- SEQUENCE_OF_STATEMENTS
-- [exception
-- EXCEPTION_HANDLER
-- {EXCEPTION_HANDLER}]
-- [at end
-- cleanup_procedure_call (param, param, param, ...);]
-- The AT END phrase is a GNAT extension to provide for cleanups. It is
-- used only internally currently, but is considered to be syntactic.
-- At the moment, the only cleanup action allowed is a single call to
-- a parameterless procedure, and the Identifier field of the node is
-- the procedure to be called. The cleanup action occurs whenever the
-- sequence of statements is left for any reason. The possible reasons
-- are:
-- 1. reaching the end of the sequence
-- 2. exit, return, or goto
-- 3. exception or abort
-- For some back ends, such as gcc with ZCX, "at end" is implemented
-- entirely in the back end. In this case, a handled sequence of
-- statements with an "at end" cannot also have exception handlers.
-- For other back ends, such as gcc with front-end SJLJ, the
-- implementation is split between the front end and back end; the front
-- end implements 3, and the back end implements 1 and 2. In this case,
-- if there is an "at end", the front end inserts the appropriate
-- exception handler, and this handler takes precedence over "at end"
-- in case of exception.
-- The inserted exception handler is of the form:
-- when all others =>
-- cleanup;
-- raise;
-- where cleanup is the procedure to be called. The reason we do this is
-- so that the front end can handle the necessary entries in the
-- exception tables, and other exception handler actions required as
-- part of the normal handling for exception handlers.
-- The AT END cleanup handler protects only the sequence of statements
-- (not the associated declarations of the parent), just like exception
-- handlers. The big difference is that the cleanup procedure is called
-- on either a normal or an abnormal exit from the statement sequence.
-- Note: the list of Exception_Handlers can contain pragmas as well
-- as actual handlers. In practice these pragmas can only occur at
-- the start of the list, since any pragmas occurring later on will
-- be included in the statement list of the corresponding handler.
-- Note: although in the Ada syntax, the sequence of statements in
-- a handled sequence of statements can only contain statements, we
-- allow free mixing of declarations and statements in the resulting
-- expanded tree. This is for example used to deal with the case of
-- a cleanup procedure that must handle declarations as well as the
-- statements of a block.
-- Note: the cleanup_procedure_call does not go through the common
-- processing for calls, which in particular means that it will not be
-- automatically inlined in all cases, even though the procedure to be
-- called is marked inline. More specifically, if the procedure comes
-- from another unit than the main source unit, for example a run-time
-- unit, then it needs to be manually added to the list of bodies to be
-- inlined by invoking Add_Inlined_Body on it.
-- N_Handled_Sequence_Of_Statements
-- Sloc points to first token of first statement
-- Statements
-- End_Label (set to Empty if expander generated)
-- Exception_Handlers (set to No_List if none present)
-- At_End_Proc (set to Empty if no clean up procedure)
-- First_Real_Statement
-- Note: the parent always contains a Declarations field which contains
-- declarations associated with the handled sequence of statements. This
-- is true even in the case of an accept statement (see description of
-- the N_Accept_Statement node).
-- End_Label refers to the containing construct
-----------------------------
-- 11.2 Exception Handler --
-----------------------------
-- EXCEPTION_HANDLER ::=
-- when [CHOICE_PARAMETER_SPECIFICATION :]
-- EXCEPTION_CHOICE {| EXCEPTION_CHOICE} =>
-- SEQUENCE_OF_STATEMENTS
-- Note: choice parameter specification is not allowed in Ada 83 mode
-- N_Exception_Handler
-- Sloc points to WHEN
-- Choice_Parameter (set to Empty if not present)
-- Exception_Choices
-- Statements
-- Exception_Label (set to Empty if not present)
-- Local_Raise_Statements (set to No_Elist if not present)
-- Local_Raise_Not_OK
-- Has_Local_Raise
------------------------------------------
-- 11.2 Choice parameter specification --
------------------------------------------
-- CHOICE_PARAMETER_SPECIFICATION ::= DEFINING_IDENTIFIER
----------------------------
-- 11.2 Exception Choice --
----------------------------
-- EXCEPTION_CHOICE ::= exception_NAME | others
-- Except in the case of OTHERS, no explicit node appears in the tree
-- for exception choice. Instead the exception name appears directly.
-- An OTHERS choice is represented by a N_Others_Choice node (see
-- section 3.8.1.
-- Note: for the exception choice created for an at end handler, the
-- exception choice is an N_Others_Choice node with All_Others set.
---------------------------
-- 11.3 Raise Statement --
---------------------------
-- RAISE_STATEMENT ::= raise [exception_NAME];
-- In Ada 2005, we have
-- RAISE_STATEMENT ::=
-- raise; | raise exception_NAME [with string_EXPRESSION];
-- N_Raise_Statement
-- Sloc points to RAISE
-- Name (set to Empty if no exception name present)
-- Expression (set to Empty if no expression present)
-- From_At_End
----------------------------
-- 11.3 Raise Expression --
----------------------------
-- RAISE_EXPRESSION ::= raise exception_NAME [with string_EXPRESSION]
-- N_Raise_Expression
-- Sloc points to RAISE
-- Name (always present)
-- Expression (set to Empty if no expression present)
-- Convert_To_Return_False
-- plus fields for expression
-------------------------------
-- 12.1 Generic Declaration --
-------------------------------
-- GENERIC_DECLARATION ::=
-- GENERIC_SUBPROGRAM_DECLARATION | GENERIC_PACKAGE_DECLARATION
------------------------------------------
-- 12.1 Generic Subprogram Declaration --
------------------------------------------
-- GENERIC_SUBPROGRAM_DECLARATION ::=
-- GENERIC_FORMAL_PART SUBPROGRAM_SPECIFICATION
-- [ASPECT_SPECIFICATIONS];
-- Note: Generic_Formal_Declarations can include pragmas
-- N_Generic_Subprogram_Declaration
-- Sloc points to GENERIC
-- Specification subprogram specification
-- Corresponding_Body
-- Generic_Formal_Declarations from generic formal part
-- Parent_Spec
---------------------------------------
-- 12.1 Generic Package Declaration --
---------------------------------------
-- GENERIC_PACKAGE_DECLARATION ::=
-- GENERIC_FORMAL_PART PACKAGE_SPECIFICATION
-- [ASPECT_SPECIFICATIONS];
-- Note: when we do generics right, the Activation_Chain_Entity entry
-- for this node can be removed (since the expander won't see generic
-- units any more)???.
-- Note: Generic_Formal_Declarations can include pragmas
-- N_Generic_Package_Declaration
-- Sloc points to GENERIC
-- Specification package specification
-- Corresponding_Body
-- Generic_Formal_Declarations from generic formal part
-- Parent_Spec
-- Activation_Chain_Entity
-------------------------------
-- 12.1 Generic Formal Part --
-------------------------------
-- GENERIC_FORMAL_PART ::=
-- generic {GENERIC_FORMAL_PARAMETER_DECLARATION | USE_CLAUSE}
------------------------------------------------
-- 12.1 Generic Formal Parameter Declaration --
------------------------------------------------
-- GENERIC_FORMAL_PARAMETER_DECLARATION ::=
-- FORMAL_OBJECT_DECLARATION
-- | FORMAL_TYPE_DECLARATION
-- | FORMAL_SUBPROGRAM_DECLARATION
-- | FORMAL_PACKAGE_DECLARATION
---------------------------------
-- 12.3 Generic Instantiation --
---------------------------------
-- GENERIC_INSTANTIATION ::=
-- package DEFINING_PROGRAM_UNIT_NAME is
-- new generic_package_NAME [GENERIC_ACTUAL_PART]
-- [ASPECT_SPECIFICATIONS];
-- | [[not] overriding]
-- procedure DEFINING_PROGRAM_UNIT_NAME is
-- new generic_procedure_NAME [GENERIC_ACTUAL_PART]
-- [ASPECT_SPECIFICATIONS];
-- | [[not] overriding]
-- function DEFINING_DESIGNATOR is
-- new generic_function_NAME [GENERIC_ACTUAL_PART]
-- [ASPECT_SPECIFICATIONS];
-- N_Package_Instantiation
-- Sloc points to PACKAGE
-- Defining_Unit_Name
-- Name
-- Generic_Associations (set to No_List if no
-- generic actual part)
-- Parent_Spec
-- Instance_Spec
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Is_Declaration_Level_Node
-- Is_Known_Guaranteed_ABE
-- N_Procedure_Instantiation
-- Sloc points to PROCEDURE
-- Defining_Unit_Name
-- Name
-- Parent_Spec
-- Generic_Associations (set to No_List if no
-- generic actual part)
-- Instance_Spec
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Is_Declaration_Level_Node
-- Must_Override set if overriding indicator present
-- Must_Not_Override set if not_overriding indicator present
-- Is_Known_Guaranteed_ABE
-- N_Function_Instantiation
-- Sloc points to FUNCTION
-- Defining_Unit_Name
-- Name
-- Generic_Associations (set to No_List if no
-- generic actual part)
-- Parent_Spec
-- Instance_Spec
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Is_Declaration_Level_Node
-- Must_Override set if overriding indicator present
-- Must_Not_Override set if not_overriding indicator present
-- Is_Known_Guaranteed_ABE
-- Note: overriding indicator is an Ada 2005 feature
-------------------------------
-- 12.3 Generic Actual Part --
-------------------------------
-- GENERIC_ACTUAL_PART ::=
-- (GENERIC_ASSOCIATION {, GENERIC_ASSOCIATION})
-------------------------------
-- 12.3 Generic Association --
-------------------------------
-- GENERIC_ASSOCIATION ::=
-- [generic_formal_parameter_SELECTOR_NAME =>]
-- Note: unlike the procedure call case, a generic association node
-- is generated for every association, even if no formal parameter
-- selector name is present. In this case the parser will leave the
-- Selector_Name field set to Empty, to be filled in later by the
-- semantic pass.
-- In Ada 2005, a formal may be associated with a box, if the
-- association is part of the list of actuals for a formal package.
-- If the association is given by OTHERS => <>, the association is
-- an N_Others_Choice.
-- N_Generic_Association
-- Sloc points to first token of generic association
-- Selector_Name (set to Empty if no formal
-- parameter selector name)
-- Explicit_Generic_Actual_Parameter (Empty if box present)
-- Box_Present (for formal_package associations with a box)
---------------------------------------------
-- 12.3 Explicit Generic Actual Parameter --
---------------------------------------------
-- EXPLICIT_GENERIC_ACTUAL_PARAMETER ::=
-- EXPRESSION | variable_NAME | subprogram_NAME
-- | entry_NAME | SUBTYPE_MARK | package_instance_NAME
-------------------------------------
-- 12.4 Formal Object Declaration --
-------------------------------------
-- FORMAL_OBJECT_DECLARATION ::=
-- DEFINING_IDENTIFIER_LIST :
-- MODE [NULL_EXCLUSION] SUBTYPE_MARK [:= DEFAULT_EXPRESSION]
-- [ASPECT_SPECIFICATIONS];
-- | DEFINING_IDENTIFIER_LIST :
-- MODE ACCESS_DEFINITION [:= DEFAULT_EXPRESSION]
-- [ASPECT_SPECIFICATIONS];
-- Although the syntax allows multiple identifiers in the list, the
-- semantics is as though successive declarations were given with
-- identical type definition and expression components. To simplify
-- semantic processing, the parser represents a multiple declaration
-- case as a sequence of single declarations, using the More_Ids and
-- Prev_Ids flags to preserve the original source form as described
-- in the section on "Handling of Defining Identifier Lists".
-- N_Formal_Object_Declaration
-- Sloc points to first identifier
-- Defining_Identifier
-- In_Present
-- Out_Present
-- Null_Exclusion_Present (set to False if not present)
-- Subtype_Mark (set to Empty if not present)
-- Access_Definition (set to Empty if not present)
-- Default_Expression (set to Empty if no default expression)
-- More_Ids (set to False if no more identifiers in list)
-- Prev_Ids (set to False if no previous identifiers in list)
-----------------------------------
-- 12.5 Formal Type Declaration --
-----------------------------------
-- FORMAL_TYPE_DECLARATION ::=
-- type DEFINING_IDENTIFIER [DISCRIMINANT_PART]
-- is FORMAL_TYPE_DEFINITION
-- [ASPECT_SPECIFICATIONS];
-- | type DEFINING_IDENTIFIER [DISCRIMINANT_PART] [is tagged]
-- N_Formal_Type_Declaration
-- Sloc points to TYPE
-- Defining_Identifier
-- Formal_Type_Definition
-- Discriminant_Specifications (set to No_List if no
-- discriminant part)
-- Unknown_Discriminants_Present set if (<>) discriminant
-- Default_Subtype_Mark
----------------------------------
-- 12.5 Formal type definition --
----------------------------------
-- FORMAL_TYPE_DEFINITION ::=
-- FORMAL_PRIVATE_TYPE_DEFINITION
-- | FORMAL_DERIVED_TYPE_DEFINITION
-- | FORMAL_DISCRETE_TYPE_DEFINITION
-- | FORMAL_SIGNED_INTEGER_TYPE_DEFINITION
-- | FORMAL_MODULAR_TYPE_DEFINITION
-- | FORMAL_FLOATING_POINT_DEFINITION
-- | FORMAL_ORDINARY_FIXED_POINT_DEFINITION
-- | FORMAL_DECIMAL_FIXED_POINT_DEFINITION
-- | FORMAL_ARRAY_TYPE_DEFINITION
-- | FORMAL_ACCESS_TYPE_DEFINITION
-- | FORMAL_INTERFACE_TYPE_DEFINITION
-- | FORMAL_INCOMPLETE_TYPE_DEFINITION
-- The Ada 2012 syntax introduces two new non-terminals:
-- Formal_{Complete,Incomplete}_Type_Declaration just to introduce
-- the latter category. Here we introduce an incomplete type definition
-- in order to preserve as much as possible the existing structure.
---------------------------------------------
-- 12.5.1 Formal Private Type Definition --
---------------------------------------------
-- FORMAL_PRIVATE_TYPE_DEFINITION ::=
-- [[abstract] tagged] [limited] private
-- Note: TAGGED is not allowed in Ada 83 mode
-- N_Formal_Private_Type_Definition
-- Sloc points to PRIVATE
-- Uninitialized_Variable
-- Abstract_Present
-- Tagged_Present
-- Limited_Present
--------------------------------------------
-- 12.5.1 Formal Derived Type Definition --
--------------------------------------------
-- FORMAL_DERIVED_TYPE_DEFINITION ::=
-- [abstract] [limited | synchronized]
-- new SUBTYPE_MARK [[and INTERFACE_LIST] with private]
-- Note: this construct is not allowed in Ada 83 mode
-- N_Formal_Derived_Type_Definition
-- Sloc points to NEW
-- Subtype_Mark
-- Private_Present
-- Abstract_Present
-- Limited_Present
-- Synchronized_Present
-- Interface_List (set to No_List if none)
-----------------------------------------------
-- 12.5.1 Formal Incomplete Type Definition --
-----------------------------------------------
-- FORMAL_INCOMPLETE_TYPE_DEFINITION ::= [tagged]
-- N_Formal_Incomplete_Type_Definition
-- Sloc points to identifier of parent
-- Tagged_Present
---------------------------------------------
-- 12.5.2 Formal Discrete Type Definition --
---------------------------------------------
-- FORMAL_DISCRETE_TYPE_DEFINITION ::= (<>)
-- N_Formal_Discrete_Type_Definition
-- Sloc points to (
---------------------------------------------------
-- 12.5.2 Formal Signed Integer Type Definition --
---------------------------------------------------
-- FORMAL_SIGNED_INTEGER_TYPE_DEFINITION ::= range <>
-- N_Formal_Signed_Integer_Type_Definition
-- Sloc points to RANGE
--------------------------------------------
-- 12.5.2 Formal Modular Type Definition --
--------------------------------------------
-- FORMAL_MODULAR_TYPE_DEFINITION ::= mod <>
-- N_Formal_Modular_Type_Definition
-- Sloc points to MOD
----------------------------------------------
-- 12.5.2 Formal Floating Point Definition --
----------------------------------------------
-- FORMAL_FLOATING_POINT_DEFINITION ::= digits <>
-- N_Formal_Floating_Point_Definition
-- Sloc points to DIGITS
----------------------------------------------------
-- 12.5.2 Formal Ordinary Fixed Point Definition --
----------------------------------------------------
-- FORMAL_ORDINARY_FIXED_POINT_DEFINITION ::= delta <>
-- N_Formal_Ordinary_Fixed_Point_Definition
-- Sloc points to DELTA
---------------------------------------------------
-- 12.5.2 Formal Decimal Fixed Point Definition --
---------------------------------------------------
-- FORMAL_DECIMAL_FIXED_POINT_DEFINITION ::= delta <> digits <>
-- Note: formal decimal fixed point definition not allowed in Ada 83
-- N_Formal_Decimal_Fixed_Point_Definition
-- Sloc points to DELTA
------------------------------------------
-- 12.5.3 Formal Array Type Definition --
------------------------------------------
-- FORMAL_ARRAY_TYPE_DEFINITION ::= ARRAY_TYPE_DEFINITION
-------------------------------------------
-- 12.5.4 Formal Access Type Definition --
-------------------------------------------
-- FORMAL_ACCESS_TYPE_DEFINITION ::= ACCESS_TYPE_DEFINITION
----------------------------------------------
-- 12.5.5 Formal Interface Type Definition --
----------------------------------------------
-- FORMAL_INTERFACE_TYPE_DEFINITION ::= INTERFACE_TYPE_DEFINITION
-----------------------------------------
-- 12.6 Formal Subprogram Declaration --
-----------------------------------------
-- FORMAL_SUBPROGRAM_DECLARATION ::=
-- FORMAL_CONCRETE_SUBPROGRAM_DECLARATION
-- | FORMAL_ABSTRACT_SUBPROGRAM_DECLARATION
--------------------------------------------------
-- 12.6 Formal Concrete Subprogram Declaration --
--------------------------------------------------
-- FORMAL_CONCRETE_SUBPROGRAM_DECLARATION ::=
-- with SUBPROGRAM_SPECIFICATION [is SUBPROGRAM_DEFAULT]
-- [ASPECT_SPECIFICATIONS];
-- N_Formal_Concrete_Subprogram_Declaration
-- Sloc points to WITH
-- Specification
-- Default_Name (set to Empty if no subprogram default)
-- Box_Present
-- Note: if no subprogram default is present, then Name is set
-- to Empty, and Box_Present is False.
--------------------------------------------------
-- 12.6 Formal Abstract Subprogram Declaration --
--------------------------------------------------
-- FORMAL_ABSTRACT_SUBPROGRAM_DECLARATION ::=
-- with SUBPROGRAM_SPECIFICATION is abstract [SUBPROGRAM_DEFAULT]
-- [ASPECT_SPECIFICATIONS];
-- N_Formal_Abstract_Subprogram_Declaration
-- Sloc points to WITH
-- Specification
-- Default_Name (set to Empty if no subprogram default)
-- Box_Present
-- Note: if no subprogram default is present, then Name is set
-- to Empty, and Box_Present is False.
------------------------------
-- 12.6 Subprogram Default --
------------------------------
-- SUBPROGRAM_DEFAULT ::= DEFAULT_NAME | <>
-- There is no separate node in the tree for a subprogram default.
-- Instead the parent (N_Formal_Concrete_Subprogram_Declaration
-- or N_Formal_Abstract_Subprogram_Declaration) node contains the
-- default name or box indication, as needed.
------------------------
-- 12.6 Default Name --
------------------------
-- DEFAULT_NAME ::= NAME
--------------------------------------
-- 12.7 Formal Package Declaration --
--------------------------------------
-- FORMAL_PACKAGE_DECLARATION ::=
-- with package DEFINING_IDENTIFIER
-- is new generic_package_NAME FORMAL_PACKAGE_ACTUAL_PART
-- [ASPECT_SPECIFICATIONS];
-- Note: formal package declarations not allowed in Ada 83 mode
-- N_Formal_Package_Declaration
-- Sloc points to WITH
-- Defining_Identifier
-- Name
-- Generic_Associations (set to No_List if (<>) case or
-- empty generic actual part)
-- Box_Present
-- Instance_Spec
-- Is_Known_Guaranteed_ABE
--------------------------------------
-- 12.7 Formal Package Actual Part --
--------------------------------------
-- FORMAL_PACKAGE_ACTUAL_PART ::=
-- ([OTHERS] => <>)
-- | [GENERIC_ACTUAL_PART]
-- (FORMAL_PACKAGE_ASSOCIATION {. FORMAL_PACKAGE_ASSOCIATION}
-- FORMAL_PACKAGE_ASSOCIATION ::=
-- GENERIC_ASSOCIATION
-- | GENERIC_FORMAL_PARAMETER_SELECTOR_NAME => <>
-- There is no explicit node in the tree for a formal package actual
-- part. Instead the information appears in the parent node (i.e. the
-- formal package declaration node itself).
-- There is no explicit node for a formal package association. All of
-- them are represented either by a generic association, possibly with
-- Box_Present, or by an N_Others_Choice.
---------------------------------
-- 13.1 Representation clause --
---------------------------------
-- REPRESENTATION_CLAUSE ::=
-- ATTRIBUTE_DEFINITION_CLAUSE
-- | ENUMERATION_REPRESENTATION_CLAUSE
-- | RECORD_REPRESENTATION_CLAUSE
-- | AT_CLAUSE
----------------------
-- 13.1 Local Name --
----------------------
-- LOCAL_NAME :=
-- DIRECT_NAME
-- | DIRECT_NAME'ATTRIBUTE_DESIGNATOR
-- | library_unit_NAME
-- The construct DIRECT_NAME'ATTRIBUTE_DESIGNATOR appears in the tree
-- as an attribute reference, which has essentially the same form.
---------------------------------------
-- 13.3 Attribute definition clause --
---------------------------------------
-- ATTRIBUTE_DEFINITION_CLAUSE ::=
-- for LOCAL_NAME'ATTRIBUTE_DESIGNATOR use EXPRESSION;
-- | for LOCAL_NAME'ATTRIBUTE_DESIGNATOR use NAME;
-- In Ada 83, the expression must be a simple expression and the
-- local name must be a direct name.
-- Note: the only attribute definition clause that is processed by
-- gigi is an address clause. For all other cases, the information
-- is extracted by the front end and either results in setting entity
-- information, e.g. Esize for the Size clause, or in appropriate
-- expansion actions (e.g. in the case of Storage_Size).
-- For an address clause, Gigi constructs the appropriate addressing
-- code. It also ensures that no aliasing optimizations are made
-- for the object for which the address clause appears.
-- Note: for an address clause used to achieve an overlay:
-- A : Integer;
-- B : Integer;
-- for B'Address use A'Address;
-- the above rule means that Gigi will ensure that no optimizations
-- will be made for B that would violate the implementation advice
-- of RM 13.3(19). However, this advice applies only to B and not
-- to A, which seems unfortunate. The GNAT front end will mark the
-- object A as volatile to also prevent unwanted optimization
-- assumptions based on no aliasing being made for B.
-- N_Attribute_Definition_Clause
-- Sloc points to FOR
-- Name the local name
-- Chars the identifier name from the attribute designator
-- Expression the expression or name
-- Entity
-- Next_Rep_Item
-- From_At_Mod
-- Check_Address_Alignment
-- From_Aspect_Specification
-- Is_Delayed_Aspect
-- Address_Warning_Posted
-- Note: if From_Aspect_Specification is set, then Sloc points to the
-- aspect name, and Entity is resolved already to reference the entity
-- to which the aspect applies.
-----------------------------------
-- 13.3.1 Aspect Specifications --
-----------------------------------
-- We modify the RM grammar here, the RM grammar is:
-- ASPECT_SPECIFICATION ::=
-- with ASPECT_MARK [=> ASPECT_DEFINITION] {,
-- ASPECT_MARK [=> ASPECT_DEFINITION] }
-- ASPECT_MARK ::= aspect_IDENTIFIER['Class]
-- ASPECT_DEFINITION ::= NAME | EXPRESSION
-- That's inconvenient, since there is no non-terminal name for a single
-- entry in the list of aspects. So we use this grammar instead:
-- ASPECT_SPECIFICATIONS ::=
-- with ASPECT_SPECIFICATION {, ASPECT_SPECIFICATION}
-- ASPECT_SPECIFICATION =>
-- ASPECT_MARK [=> ASPECT_DEFINITION]
-- ASPECT_MARK ::= aspect_IDENTIFIER['Class]
-- ASPECT_DEFINITION ::= NAME | EXPRESSION
-- Note that for Annotate, the ASPECT_DEFINITION is a pure positional
-- aggregate with the elements of the aggregate corresponding to the
-- successive arguments of the corresponding pragma.
-- See separate package Aspects for details on the incorporation of
-- these nodes into the tree, and how aspect specifications for a given
-- declaration node are associated with that node.
-- N_Aspect_Specification
-- Sloc points to aspect identifier
-- Identifier aspect identifier
-- Aspect_Rep_Item
-- Expression (set to Empty if none)
-- Entity entity to which the aspect applies
-- Next_Rep_Item
-- Class_Present Set if 'Class present
-- Is_Ignored
-- Is_Checked
-- Is_Delayed_Aspect
-- Is_Disabled
-- Is_Boolean_Aspect
-- Split_PPC Set if split pre/post attribute
-- Aspect_On_Partial_View
-- Note: Aspect_Specification is an Ada 2012 feature
-- Note: The Identifier serves to identify the aspect involved (it
-- is the aspect whose name corresponds to the Chars field). This
-- means that the other fields of this identifier are unused, and
-- in particular we use the Entity field of this identifier to save
-- a copy of the expression for visibility analysis, see spec of
-- Sem_Ch13 for full details of this usage.
-- In the case of aspects of the form xxx'Class, the aspect identifier
-- is for xxx, and Class_Present is set to True.
-- Note: When a Pre or Post aspect specification is processed, it is
-- broken into AND THEN sections. The left most section has Split_PPC
-- set to False, indicating that it is the original specification (e.g.
-- for posting errors). For the other sections, Split_PPC is set True.
---------------------------------------------
-- 13.4 Enumeration representation clause --
---------------------------------------------
-- ENUMERATION_REPRESENTATION_CLAUSE ::=
-- for first_subtype_LOCAL_NAME use ENUMERATION_AGGREGATE;
-- In Ada 83, the name must be a direct name
-- N_Enumeration_Representation_Clause
-- Sloc points to FOR
-- Identifier direct name
-- Array_Aggregate
-- Next_Rep_Item
---------------------------------
-- 13.4 Enumeration aggregate --
---------------------------------
-- ENUMERATION_AGGREGATE ::= ARRAY_AGGREGATE
------------------------------------------
-- 13.5.1 Record representation clause --
------------------------------------------
-- RECORD_REPRESENTATION_CLAUSE ::=
-- for first_subtype_LOCAL_NAME use
-- record [MOD_CLAUSE]
-- {COMPONENT_CLAUSE}
-- end record;
-- Gigi restriction: Mod_Clause is always Empty (if present it is
-- replaced by a corresponding Alignment attribute definition clause).
-- Note: Component_Clauses can include pragmas
-- N_Record_Representation_Clause
-- Sloc points to FOR
-- Identifier direct name
-- Mod_Clause (set to Empty if no mod clause present)
-- Component_Clauses
-- Next_Rep_Item
------------------------------
-- 13.5.1 Component clause --
------------------------------
-- COMPONENT_CLAUSE ::=
-- component_LOCAL_NAME at POSITION
-- range FIRST_BIT .. LAST_BIT;
-- N_Component_Clause
-- Sloc points to AT
-- Component_Name points to Name or Attribute_Reference
-- Position
-- First_Bit
-- Last_Bit
----------------------
-- 13.5.1 Position --
----------------------
-- POSITION ::= static_EXPRESSION
-----------------------
-- 13.5.1 First_Bit --
-----------------------
-- FIRST_BIT ::= static_SIMPLE_EXPRESSION
----------------------
-- 13.5.1 Last_Bit --
----------------------
-- LAST_BIT ::= static_SIMPLE_EXPRESSION
--------------------------
-- 13.8 Code statement --
--------------------------
-- CODE_STATEMENT ::= QUALIFIED_EXPRESSION;
-- Note: in GNAT, the qualified expression has the form
-- Asm_Insn'(Asm (...));
-- See package System.Machine_Code in file s-maccod.ads for details on
-- the allowed parameters to Asm. There are two ways this node can
-- arise, as a code statement, in which case the expression is the
-- qualified expression, or as a result of the expansion of an intrinsic
-- call to the Asm or Asm_Input procedure.
-- N_Code_Statement
-- Sloc points to first token of the expression
-- Expression
-- Note: package Exp_Code contains an abstract functional interface
-- for use by Gigi in accessing the data from N_Code_Statement nodes.
------------------------
-- 13.12 Restriction --
------------------------
-- RESTRICTION ::=
-- restriction_IDENTIFIER
-- | restriction_parameter_IDENTIFIER => EXPRESSION
-- There is no explicit node for restrictions. Instead the restriction
-- appears in normal pragma syntax as a pragma argument association,
-- which has the same syntactic form.
--------------------------
-- B.2 Shift Operators --
--------------------------
-- Calls to the intrinsic shift functions are converted to one of
-- the following shift nodes, which have the form of normal binary
-- operator names. Note that for a given shift operation, one node
-- covers all possible types, as for normal operators.
-- Note: it is perfectly permissible for the expander to generate
-- shift operation nodes directly, in which case they will be analyzed
-- and parsed in the usual manner.
-- Sprint syntax: shift-function-name!(expr, count)
-- Note: the Left_Opnd field holds the first argument (the value to
-- be shifted). The Right_Opnd field holds the second argument (the
-- shift count). The Chars field is the name of the intrinsic function.
-- N_Op_Rotate_Left
-- Sloc points to the function name
-- plus fields for binary operator
-- plus fields for expression
-- Shift_Count_OK
-- N_Op_Rotate_Right
-- Sloc points to the function name
-- plus fields for binary operator
-- plus fields for expression
-- Shift_Count_OK
-- N_Op_Shift_Left
-- Sloc points to the function name
-- plus fields for binary operator
-- plus fields for expression
-- Shift_Count_OK
-- N_Op_Shift_Right_Arithmetic
-- Sloc points to the function name
-- plus fields for binary operator
-- plus fields for expression
-- Shift_Count_OK
-- N_Op_Shift_Right
-- Sloc points to the function name
-- plus fields for binary operator
-- plus fields for expression
-- Shift_Count_OK
-- Note: N_Op_Rotate_Left, N_Op_Rotate_Right, N_Shift_Right_Arithmetic
-- never appear in the expanded tree if Modify_Tree_For_C mode is set.
-- Note: For N_Op_Shift_Left and N_Op_Shift_Right, the right operand is
-- always less than the word size if Modify_Tree_For_C mode is set.
--------------------------
-- Obsolescent Features --
--------------------------
-- The syntax descriptions and tree nodes for obsolescent features are
-- grouped together, corresponding to their location in appendix I in
-- the RM. However, parsing and semantic analysis for these constructs
-- is located in an appropriate chapter (see individual notes).
---------------------------
-- J.3 Delta Constraint --
---------------------------
-- Note: the parse routine for this construct is located in section
-- 3.5.9 of Par-Ch3, and semantic analysis is in Sem_Ch3, which is
-- where delta constraint logically belongs.
-- DELTA_CONSTRAINT ::= DELTA static_EXPRESSION [RANGE_CONSTRAINT]
-- N_Delta_Constraint
-- Sloc points to DELTA
-- Delta_Expression
-- Range_Constraint (set to Empty if not present)
--------------------
-- J.7 At Clause --
--------------------
-- AT_CLAUSE ::= for DIRECT_NAME use at EXPRESSION;
-- Note: the parse routine for this construct is located in Par-Ch13,
-- and the semantic analysis is in Sem_Ch13, where at clause logically
-- belongs if it were not obsolescent.
-- Note: in Ada 83 the expression must be a simple expression
-- Gigi restriction: This node never appears, it is rewritten as an
-- address attribute definition clause.
-- N_At_Clause
-- Sloc points to FOR
-- Identifier
-- Expression
---------------------
-- J.8 Mod clause --
---------------------
-- MOD_CLAUSE ::= at mod static_EXPRESSION;
-- Note: the parse routine for this construct is located in Par-Ch13,
-- and the semantic analysis is in Sem_Ch13, where mod clause logically
-- belongs if it were not obsolescent.
-- Note: in Ada 83, the expression must be a simple expression
-- Gigi restriction: this node never appears. It is replaced
-- by a corresponding Alignment attribute definition clause.
-- Note: pragmas can appear before and after the MOD_CLAUSE since
-- its name has "clause" in it. This is rather strange, but is quite
-- definitely specified. The pragmas before are collected in the
-- Pragmas_Before field of the mod clause node itself, and pragmas
-- after are simply swallowed up in the list of component clauses.
-- N_Mod_Clause
-- Sloc points to AT
-- Expression
-- Pragmas_Before Pragmas before mod clause (No_List if none)
--------------------
-- Semantic Nodes --
--------------------
-- These semantic nodes are used to hold additional semantic information.
-- They are inserted into the tree as a result of semantic processing.
-- Although there are no legitimate source syntax constructions that
-- correspond directly to these nodes, we need a source syntax for the
-- reconstructed tree printed by Sprint, and the node descriptions here
-- show this syntax.
-----------------
-- Call_Marker --
-----------------
-- This node is created during the analysis/resolution of entry calls,
-- requeues, and subprogram calls. It performs several functions:
-- * Call markers provide a uniform model for handling calls by the
-- ABE mechanism, regardless of whether expansion took place.
-- * The call marker captures the target of the related call along
-- with other attributes which are either unavailabe or expensive
-- to recompute once analysis, resolution, and expansion are over.
-- * The call marker aids the ABE Processing phase by signaling the
-- presence of a call in case the original call was transformed by
-- expansion.
-- * The call marker acts as a reference point for the insertion of
-- run-time conditional ABE checks or guaranteed ABE failures.
-- Sprint syntax: #target#
-- The Sprint syntax shown above is not enabled by default
-- N_Call_Marker
-- Sloc points to Sloc of original call
-- Target
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Is_Source_Call
-- Is_Declaration_Level_Node
-- Is_Dispatching_Call
-- Is_Preelaborable_Call
-- Is_Known_Guaranteed_ABE
------------------------
-- Compound Statement --
------------------------
-- This node is created by the analyzer/expander to handle some
-- expansion cases where a sequence of actions needs to be captured
-- within a single node (which acts as a container and allows the
-- entire list of actions to be moved around as a whole) appearing
-- in a sequence of statements.
-- This is the statement counterpart to the expression node
-- N_Expression_With_Actions.
-- The required semantics is that the set of actions is executed in
-- the order in which it appears, as though they appeared by themselves
-- in the enclosing list of declarations or statements. Unlike what
-- happens when using an N_Block_Statement, no new scope is introduced.
-- Note: for the time being, this is used only as a transient
-- representation during expansion, and all compound statement nodes
-- must be exploded back to their constituent statements before handing
-- the tree to the back end.
-- Sprint syntax: do
-- action;
-- action;
-- ...
-- action;
-- end;
-- N_Compound_Statement
-- Actions
--------------
-- Contract --
--------------
-- This node is used to hold the various parts of an entry, subprogram
-- [body] or package [body] contract, in particular:
-- Abstract states declared by a package declaration
-- Contract cases that apply to a subprogram
-- Dependency relations of inputs and output of a subprogram
-- Global annotations classifying data as input or output
-- Initialization sequences for a package declaration
-- Pre- and postconditions that apply to a subprogram
-- The node appears in an entry and [generic] subprogram [body] entity.
-- Sprint syntax: <none> as the node should not appear in the tree, but
-- only attached to an entry or [generic] subprogram
-- entity.
-- N_Contract
-- Sloc points to the subprogram's name
-- Pre_Post_Conditions (set to Empty if none)
-- Contract_Test_Cases (set to Empty if none)
-- Classifications (set to Empty if none)
-- Is_Expanded_Contract
-- Pre_Post_Conditions contains a collection of pragmas that correspond
-- to pre- and postconditions associated with an entry or a subprogram
-- [body or stub]. The pragmas can either come from source or be the
-- byproduct of aspect expansion. Currently the following pragmas appear
-- in this list:
-- Post
-- Postcondition
-- Pre
-- Precondition
-- Refined_Post
-- The ordering in the list is in LIFO fashion.
-- Note that there might be multiple preconditions or postconditions
-- in this list, either because they come from separate pragmas in the
-- source, or because a Pre (resp. Post) aspect specification has been
-- broken into AND THEN sections. See Split_PPC for details.
-- In GNATprove mode, the inherited classwide pre- and postconditions
-- (suitably specialized for the specific type of the overriding
-- operation) are also in this list.
-- Contract_Test_Cases contains a collection of pragmas that correspond
-- to aspects/pragmas Contract_Cases, Test_Case and Subprogram_Variant.
-- The ordering in the list is in LIFO fashion.
-- Classifications contains pragmas that either declare, categorize, or
-- establish dependencies between subprogram or package inputs and
-- outputs. Currently the following pragmas appear in this list:
-- Abstract_States
-- Async_Readers
-- Async_Writers
-- Constant_After_Elaboration
-- Depends
-- Effective_Reads
-- Effective_Writes
-- Extensions_Visible
-- Global
-- Initial_Condition
-- Initializes
-- Part_Of
-- Refined_Depends
-- Refined_Global
-- Refined_States
-- Volatile_Function
-- The ordering is in LIFO fashion.
-------------------
-- Expanded Name --
-------------------
-- The N_Expanded_Name node is used to represent a selected component
-- name that has been resolved to an expanded name. The semantic phase
-- replaces N_Selected_Component nodes that represent names by the use
-- of this node, leaving the N_Selected_Component node used only when
-- the prefix is a record or protected type.
-- The fields of the N_Expanded_Name node are laid out identically
-- to those of the N_Selected_Component node, allowing conversion of
-- an expanded name node to a selected component node to be done
-- easily, see Sinfo.CN.Change_Selected_Component_To_Expanded_Name.
-- There is no special sprint syntax for an expanded name
-- N_Expanded_Name
-- Sloc points to the period
-- Chars copy of Chars field of selector name
-- Prefix
-- Selector_Name
-- Entity
-- Associated_Node
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Has_Private_View (set in generic units)
-- Redundant_Use
-- Atomic_Sync_Required
-- plus fields for expression
-----------------------------
-- Expression With Actions --
-----------------------------
-- This node is created by the analyzer/expander to handle some
-- expansion cases, notably short-circuit forms where there are
-- actions associated with the right-hand side operand.
-- The N_Expression_With_Actions node represents an expression with
-- an associated set of actions (which are executable statements and
-- declarations, as might occur in a handled statement sequence).
-- The required semantics is that the set of actions is executed in
-- the order in which it appears just before the expression is
-- evaluated (and these actions must only be executed if the value
-- of the expression is evaluated). The node is considered to be
-- a subexpression, whose value is the value of the Expression after
-- executing all the actions.
-- If the actions contain declarations, then these declarations may
-- be referenced within the expression.
-- (AI12-0236-1): In Ada 2022, for a declare_expression, the parser
-- generates an N_Expression_With_Actions. Declare_expressions have
-- various restrictions, which we do not enforce on
-- N_Expression_With_Actions nodes that are generated by the
-- expander. The two cases can be distinguished by looking at
-- Comes_From_Source.
-- ???Perhaps we should change the name of this node to
-- N_Declare_Expression, and perhaps we should change the Sprint syntax
-- to match the RM syntax for declare_expression.
-- Sprint syntax: do
-- action;
-- action;
-- ...
-- action;
-- in expression end
-- N_Expression_With_Actions
-- Actions
-- Expression
-- plus fields for expression
-- Note: In the final generated tree presented to the code generator,
-- the actions list is always non-null, since there is no point in this
-- node if the actions are Empty. During semantic analysis there are
-- cases where it is convenient to temporarily generate an empty actions
-- list. This arises in cases where we create such an empty actions
-- list, and it may or may not end up being a place where additional
-- actions are inserted. The expander removes such empty cases after
-- the expression of the node is fully analyzed and expanded, at which
-- point it is safe to remove it, since no more actions can be inserted.
-- Note: In Modify_Tree_For_C, we never generate any declarations in
-- the action list, which can contain only non-declarative statements.
--------------------
-- Free Statement --
--------------------
-- The N_Free_Statement node is generated as a result of a call to an
-- instantiation of Unchecked_Deallocation. The instantiation of this
-- generic is handled specially and generates this node directly.
-- Sprint syntax: free expression
-- N_Free_Statement
-- Sloc is copied from the unchecked deallocation call
-- Expression argument to unchecked deallocation call
-- Storage_Pool
-- Procedure_To_Call
-- Actual_Designated_Subtype
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the FREE keyword in the Sprint file output.
-------------------
-- Freeze Entity --
-------------------
-- This node marks the point in a declarative part at which an entity
-- declared therein becomes frozen. The expander places initialization
-- procedures for types at those points. Gigi uses the freezing point
-- to elaborate entities that may depend on previous private types.
-- See the section in Einfo "Delayed Freezing and Elaboration" for
-- a full description of the use of this node.
-- The Entity field points back to the entity for the type (whose
-- Freeze_Node field points back to this freeze node).
-- The Actions field contains a list of declarations and statements
-- generated by the expander which are associated with the freeze
-- node, and are elaborated as though the freeze node were replaced
-- by this sequence of actions.
-- Note: the Sloc field in the freeze node references a construct
-- associated with the freezing point. This is used for posting
-- messages in some error/warning situations, e.g. the case where
-- a primitive operation of a tagged type is declared too late.
-- Sprint syntax: freeze entity-name [
-- freeze actions
-- ]
-- N_Freeze_Entity
-- Sloc points near freeze point (see above special note)
-- Entity
-- Access_Types_To_Process (set to No_Elist if none)
-- TSS_Elist (set to No_Elist if no associated TSS's)
-- Actions (set to No_List if no freeze actions)
-- First_Subtype_Link (set to Empty if no link)
-- The Actions field holds actions associated with the freeze. These
-- actions are elaborated at the point where the type is frozen.
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the FREEZE keyword in the Sprint file output.
---------------------------
-- Freeze Generic Entity --
---------------------------
-- The freeze point of an entity indicates the point at which the
-- information needed to generate code for the entity is complete.
-- The freeze node for an entity triggers expander activities, such as
-- build initialization procedures, and backend activities, such as
-- completing the elaboration of packages.
-- For entities declared within a generic unit, for which no code is
-- generated, the freeze point is not equally meaningful. However, in
-- Ada 2012 several semantic checks on declarations must be delayed to
-- the freeze point, and we need to include such a mark in the tree to
-- trigger these checks. The Freeze_Generic_Entity node plays no other
-- role, and is ignored by the expander and the back-end.
-- Sprint syntax: freeze_generic entity-name
-- N_Freeze_Generic_Entity
-- Sloc points near freeze point
-- Entity
--------------------------------
-- Implicit Label Declaration --
--------------------------------
-- An implicit label declaration is created for every occurrence of a
-- label on a statement or a label on a block or loop. It is chained
-- in the declarations of the innermost enclosing block as specified
-- in RM section 5.1 (3).
-- The Defining_Identifier is the actual identifier for the statement
-- identifier. Note that the occurrence of the label is a reference, NOT
-- the defining occurrence. The defining occurrence occurs at the head
-- of the innermost enclosing block, and is represented by this node.
-- Note: from the grammar, this might better be called an implicit
-- statement identifier declaration, but the term we choose seems
-- friendlier, since at least informally statement identifiers are
-- called labels in both cases (i.e. when used in labels, and when
-- used as the identifiers of blocks and loops).
-- Note: although this is logically a semantic node, since it does not
-- correspond directly to a source syntax construction, these nodes are
-- actually created by the parser in a post pass done just after parsing
-- is complete, before semantic analysis is started (see Par.Labl).
-- Sprint syntax: labelname : label;
-- N_Implicit_Label_Declaration
-- Sloc points to the << token for a statement identifier, or to the
-- LOOP, DECLARE, or BEGIN token for a loop or block identifier
-- Defining_Identifier
-- Label_Construct
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the label name in the generated declaration.
---------------------
-- Itype Reference --
---------------------
-- This node is used to create a reference to an Itype. The only purpose
-- is to make sure the Itype is defined if this is the first reference.
-- A typical use of this node is when an Itype is to be referenced in
-- two branches of an IF statement. In this case it is important that
-- the first use of the Itype not be inside the conditional, since then
-- it might not be defined if the other branch of the IF is taken, in
-- the case where the definition generates elaboration code.
-- The Itype field points to the referenced Itype
-- Sprint syntax: reference itype-name
-- N_Itype_Reference
-- Sloc points to the node generating the reference
-- Itype
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the REFERENCE keyword in the file output.
---------------------
-- Raise xxx Error --
---------------------
-- One of these nodes is created during semantic analysis to replace
-- a node for an expression that is determined to definitely raise
-- the corresponding exception.
-- The N_Raise_xxx_Error node may also stand alone in place
-- of a declaration or statement, in which case it simply causes
-- the exception to be raised (i.e. it is equivalent to a raise
-- statement that raises the corresponding exception). This use
-- is distinguished by the fact that the Etype in this case is
-- Standard_Void_Type; in the subexpression case, the Etype is the
-- same as the type of the subexpression which it replaces.
-- If Condition is empty, then the raise is unconditional. If the
-- Condition field is non-empty, it is a boolean expression which is
-- first evaluated, and the exception is raised only if the value of the
-- expression is True. In the unconditional case, the creation of this
-- node is usually accompanied by a warning message (unless it appears
-- within the right operand of a short-circuit form whose left argument
-- is static and decisively eliminates elaboration of the raise
-- operation). The condition field can ONLY be present when the node is
-- used as a statement form; it must NOT be present in the case where
-- the node appears within an expression.
-- The exception is generated with a message that contains the
-- file name and line number, and then appended text. The Reason
-- code shows the text to be added. The Reason code is an element
-- of the type Types.RT_Exception_Code, and indicates both the
-- message to be added, and the exception to be raised (which must
-- match the node type). The value is stored by storing a Uint which
-- is the Pos value of the enumeration element in this type.
-- Gigi restriction: This expander ensures that the type of the
-- Condition field is always Standard.Boolean, even if the type
-- in the source is some non-standard boolean type.
-- Sprint syntax: [xxx_error "msg"]
-- or: [xxx_error when condition "msg"]
-- N_Raise_Constraint_Error
-- Sloc references related construct
-- Condition (set to Empty if no condition)
-- Reason
-- plus fields for expression
-- N_Raise_Program_Error
-- Sloc references related construct
-- Condition (set to Empty if no condition)
-- Reason
-- plus fields for expression
-- N_Raise_Storage_Error
-- Sloc references related construct
-- Condition (set to Empty if no condition)
-- Reason
-- plus fields for expression
-- Note: Sloc is copied from the expression generating the exception.
-- In the case where a debug source file is generated, the Sloc for
-- this node points to the left bracket in the Sprint file output.
-- Note: the back end may be required to translate these nodes into
-- appropriate goto statements. See description of N_Push/Pop_xxx_Label.
---------------------------------------------
-- Optimization of Exception Raise to Goto --
---------------------------------------------
-- In some cases, the front end will determine that any exception raised
-- by the back end for a certain exception should be transformed into a
-- goto statement.
-- There are three kinds of exceptions raised by the back end (note that
-- for this purpose we consider gigi to be part of the back end in the
-- gcc case):
-- 1. Exceptions resulting from N_Raise_xxx_Error nodes
-- 2. Exceptions from checks triggered by Do_xxx_Check flags
-- 3. Other cases not specifically marked by the front end
-- Normally all such exceptions are translated into calls to the proper
-- Rcheck_xx procedure, where xx encodes both the exception to be raised
-- and the exception message.
-- The front end may determine that for a particular sequence of code,
-- exceptions in any of these three categories for a particular builtin
-- exception should result in a goto, rather than a call to Rcheck_xx.
-- The exact sequence to be generated is:
-- Local_Raise (exception'Identity);
-- goto Label
-- The front end marks such a sequence of code by bracketing it with
-- push and pop nodes:
-- N_Push_xxx_Label (referencing the label)
-- ...
-- (code where transformation is expected for exception xxx)
-- ...
-- N_Pop_xxx_Label
-- The use of push/pop reflects the fact that such regions can properly
-- nest, and one special case is a subregion in which no transformation
-- is allowed. Such a region is marked by a N_Push_xxx_Label node whose
-- Exception_Label field is Empty.
-- N_Push_Constraint_Error_Label
-- Sloc references first statement in region covered
-- Exception_Label
-- N_Push_Program_Error_Label
-- Sloc references first statement in region covered
-- Exception_Label
-- N_Push_Storage_Error_Label
-- Sloc references first statement in region covered
-- Exception_Label
-- N_Pop_Constraint_Error_Label
-- Sloc references last statement in region covered
-- N_Pop_Program_Error_Label
-- Sloc references last statement in region covered
-- N_Pop_Storage_Error_Label
-- Sloc references last statement in region covered
---------------
-- Reference --
---------------
-- For a number of purposes, we need to construct references to objects.
-- These references are subsequently treated as normal access values.
-- An example is the construction of the parameter block passed to a
-- task entry. The N_Reference node is provided for this purpose. It is
-- similar in effect to the use of the Unrestricted_Access attribute,
-- and like Unrestricted_Access can be applied to objects which would
-- not be valid prefixes for the Unchecked_Access attribute (e.g.
-- objects which are not aliased, and slices). In addition it can be
-- applied to composite type values as well as objects, including string
-- values and aggregates.
-- Note: we use the Prefix field for this expression so that the
-- resulting node can be treated using common code with the attribute
-- nodes for the 'Access and related attributes. Logically it would make
-- more sense to call it an Expression field, but then we would have to
-- special case the treatment of the N_Reference node.
-- Note: evaluating a N_Reference node is guaranteed to yield a non-null
-- value at run time. Therefore, it is valid to set Is_Known_Non_Null on
-- a temporary initialized to a N_Reference node in order to eliminate
-- superfluous access checks.
-- Sprint syntax: prefix'reference
-- N_Reference
-- Sloc is copied from the expression
-- Prefix
-- plus fields for expression
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the quote in the Sprint file output.
----------------
-- SCIL Nodes --
----------------
-- SCIL nodes are special nodes added to the tree when the CodePeer mode
-- is active. They are only generated if SCIL generation is enabled.
-- A standard tree-walk will not encounter these nodes even if they
-- are present; these nodes are only accessible via the function
-- SCIL_LL.Get_SCIL_Node. These nodes have no associated dynamic
-- semantics.
-- Sprint syntax: [ <node kind> ]
-- No semantic field values are displayed.
-- N_SCIL_Dispatch_Table_Tag_Init
-- Sloc references a node for a tag initialization
-- SCIL_Entity
--
-- An N_SCIL_Dispatch_Table_Tag_Init node may be associated (via
-- Get_SCIL_Node) with the N_Object_Declaration node corresponding to
-- the declaration of the dispatch table for a tagged type.
-- N_SCIL_Dispatching_Call
-- Sloc references the node of a dispatching call
-- SCIL_Target_Prim
-- SCIL_Entity
-- SCIL_Controlling_Tag
--
-- An N_Scil_Dispatching call node may be associated (via Get_SCIL_Node)
-- with the N_Procedure_Call_Statement or N_Function_Call node (or a
-- rewriting thereof) corresponding to a dispatching call.
-- N_SCIL_Membership_Test
-- Sloc references the node of a membership test
-- SCIL_Tag_Value
-- SCIL_Entity
--
-- An N_Scil_Membership_Test node may be associated (via Get_SCIL_Node)
-- with the N_In node (or a rewriting thereof) corresponding to a
-- classwide membership test.
--------------------------
-- Unchecked Expression --
--------------------------
-- An unchecked expression is one that must be analyzed and resolved
-- with all checks off, regardless of the current setting of scope
-- suppress flags.
-- Sprint syntax: `(expression)
-- Note: this node is always removed from the tree (and replaced by
-- its constituent expression) on completion of analysis, so it only
-- appears in intermediate trees, and will never be seen by Gigi.
-- N_Unchecked_Expression
-- Sloc is a copy of the Sloc of the expression
-- Expression
-- plus fields for expression
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the back quote in the Sprint file output.
-------------------------------
-- Unchecked Type Conversion --
-------------------------------
-- An unchecked type conversion node represents the semantic action
-- corresponding to a call to an instantiation of Unchecked_Conversion.
-- It is generated as a result of actual use of Unchecked_Conversion
-- and also by the expander.
-- Unchecked type conversion nodes should be created by calling
-- Tbuild.Unchecked_Convert_To, rather than by directly calling
-- Nmake.Make_Unchecked_Type_Conversion.
-- Note: an unchecked type conversion is a variable as far as the
-- semantics are concerned, which is convenient for the expander.
-- This does not change what Ada source programs are legal, since
-- clearly a function call to an instantiation of Unchecked_Conversion
-- is not a variable in any case.
-- Sprint syntax: subtype-mark!(expression)
-- N_Unchecked_Type_Conversion
-- Sloc points to related node in source
-- Subtype_Mark
-- Expression
-- Kill_Range_Check
-- No_Truncation
-- plus fields for expression
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the exclamation in the Sprint file output.
-----------------------------------
-- Validate_Unchecked_Conversion --
-----------------------------------
-- The front end does most of the validation of unchecked conversion,
-- including checking sizes (this is done after the back end is called
-- to take advantage of back-annotation of calculated sizes).
-- The front end also deals with specific cases that are not allowed
-- e.g. involving unconstrained array types.
-- For the case of the standard gigi backend, this means that all
-- checks are done in the front end.
-- However, in the case of specialized back-ends, in particular the JVM
-- backend in the past, additional requirements and restrictions may
-- apply to unchecked conversion, and these are most conveniently
-- performed in the specialized back-end.
-- To accommodate this requirement, for such back ends, the following
-- special node is generated recording an unchecked conversion that
-- needs to be validated. The back end should post an appropriate
-- error message if the unchecked conversion is invalid or warrants
-- a special warning message.
-- Source_Type and Target_Type point to the entities for the two
-- types involved in the unchecked conversion instantiation that
-- is to be validated.
-- Sprint syntax: validate Unchecked_Conversion (source, target);
-- N_Validate_Unchecked_Conversion
-- Sloc points to instantiation (location for warning message)
-- Source_Type
-- Target_Type
-- Note: in the case where a debug source file is generated, the Sloc
-- for this node points to the VALIDATE keyword in the file output.
-------------------------------
-- Variable_Reference_Marker --
-------------------------------
-- This node is created during the analysis of direct or expanded names,
-- and the resolution of entry and subprogram calls. It performs several
-- functions:
-- * Variable reference markers provide a uniform model for handling
-- variable references by the ABE mechanism, regardless of whether
-- expansion took place.
-- * The variable reference marker captures the entity of the variable
-- being read or written.
-- * The variable reference markers aid the ABE Processing phase by
-- signaling the presence of a call in case the original variable
-- reference was transformed by expansion.
-- Sprint syntax: r#target# -- for a read
-- rw#target# -- for a read/write
-- w#target# -- for a write
-- The Sprint syntax shown above is not enabled by default
-- N_Variable_Reference_Marker
-- Sloc points to Sloc of original variable reference
-- Target
-- Is_Elaboration_Checks_OK_Node
-- Is_SPARK_Mode_On_Node
-- Is_Elaboration_Warnings_OK_Node
-- Is_Read
-- Is_Write
-----------
-- Empty --
-----------
-- Used as the contents of the Nkind field of the dummy Empty node and in
-- some other situations to indicate an uninitialized value.
-- N_Empty
-- Chars is set to No_Name
-----------
-- Error --
-----------
-- Used as the contents of the Nkind field of the dummy Error node.
-- Has an Etype field, which gets set to Any_Type later on, to help
-- error recovery (Error_Posted is also set in the Error node).
-- N_Error
-- Chars is set to Error_Name
-- Etype
end Sinfo;