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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S I N F O --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2004, 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 2, 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 COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package defines the structure of the abstract syntax tree. The Tree
-- package provides a basic tree structure. Sinfo describes how this
-- structure is used to represent the syntax of an Ada program.
-- Note: the grammar used here is taken from Version 5.95 of the RM, dated
-- November 1994. 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.
-- WARNING: There is a C version of this package. Any changes to this
-- source file must be properly reflected in this C header file sinfo.h
-- which is created automatically from sinfo.ads using xsinfo.spt.
with Types; use Types;
with Uintp; use Uintp;
with Urealp; use Urealp;
package Sinfo is
---------------------------------
-- Making Changes to This File --
---------------------------------
-- If changes are made to this file, a number of related steps must be
-- carried out to ensure consistency. First, if a field access function
-- is added, it appears in seven places:
-- The documentation associated with the node
-- The spec of the access function in sinfo.ads
-- The body of the access function in sinfo.adb
-- The pragma Inline at the end of sinfo.ads for the access function
-- The spec of the set procedure in sinfo.ads
-- The body of the set procedure in sinfo.adb
-- The pragma Inline at the end of sinfo.ads for the set procedure
-- The field chosen must be consistent in all places, and, for a node
-- that is a subexpression, must not overlap any of the standard
-- expression fields.
-- In addition, if any of the standard expression fields is changed, then
-- the utiliy program which creates the Treeprs spec (in file treeprs.ads)
-- must be updated appropriately, since it special cases expression fields.
-- If a new tree node is added, then the following changes are made
-- Add it to the documentation in the appropriate place
-- Add its fields to this documentation section
-- Define it in the appropriate classification in Node_Kind
-- In the body (sinfo), add entries to the access functions for all
-- its fields (except standard expression fields) to include the new
-- node in the checks.
-- Add an appropriate section to the case statement in sprint.adb
-- Add an appropriate section to the case statement in sem.adb
-- Add an appropraite section to the case statement in exp_util.adb
-- (Insert_Actions procedure)
-- For a subexpression, add an appropriate sections to the case
-- statement in sem_eval.adb
-- For a subexpression, add an appropriate sections to the case
-- statement in sem_res.adb
-- Finally, four utility programs must be run:
-- Run CSinfo to check that you have made the changes consistently.
-- It checks most of the rules given above, with clear error messages.
-- This utility reads sinfo.ads and sinfo.adb and generates a report
-- to standard output.
-- Run XSinfo to create a-sinfo.h, the corresponding C header. This
-- utility reads sinfo.ads and generates a-sinfo.h. Note that it
-- does not need to read sinfo.adb, since the contents of the body
-- are algorithmically determinable from the spec.
-- Run XTreeprs to create treeprs.ads, an updated version of
-- the module that is used to drive the tree print routine. This
-- utility reads (but does not modify) treeprs.adt, the template
-- that provides the basic structure of the file, and then fills
-- in the data from the comments in sinfo.ads.
-- Run XNmake to create nmake.ads and nmake.adb, the package body
-- and spec of the Nmake package which contains functions for
-- constructing nodes.
-- Note: sometime we could write a utility that actually generated the
-- body of sinfo from the spec instead of simply checking it, since, as
-- noted above, the contents of the body can be determined from the spec.
--------------------------------
-- 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 a
-- 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 a
-- 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 mode, 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 a
-- 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 simplifies 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 indentifiers, 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:
-- Note: the utility program that creates the Treeprs spec (in the file
-- xtreeprs.adb) knows about the special fields here, so it must be
-- modified if any change is made to these fields.
-- "plus fields for binary operator"
-- Chars (Name1) Name_Id for the operator
-- Left_Opnd (Node2) left operand expression
-- Right_Opnd (Node3) right operand expression
-- Entity (Node4-Sem) defining entity for operator
-- Associated_Node (Node4-Sem) for generic processing
-- Do_Overflow_Check (Flag17-Sem) set if overflow check needed
-- Has_Private_View (Flag11-Sem) set in generic units.
-- "plus fields for unary operator"
-- Chars (Name1) Name_Id for the operator
-- Right_Opnd (Node3) right operand expression
-- Entity (Node4-Sem) defining entity for operator
-- Associated_Node (Node4-Sem) for generic processing
-- Do_Overflow_Check (Flag17-Sem) set if overflow check needed
-- Has_Private_View (Flag11-Sem) set in generic units.
-- "plus fields for expression"
-- Paren_Count number of parentheses levels
-- Etype (Node5-Sem) type of the expression
-- Is_Overloaded (Flag5-Sem) >1 type interpretation exists
-- Is_Static_Expression (Flag6-Sem) set for static expression
-- Raises_Constraint_Error (Flag7-Sem) evaluation raises CE
-- Must_Not_Freeze (Flag8-Sem) set if must not freeze
-- Do_Range_Check (Flag9-Sem) set if a range check needed
-- Assignment_OK (Flag15-Sem) set if modification is OK
-- Is_Controlling_Actual (Flag16-Sem) 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.
------------------------
-- 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.
-- 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.
-- Comes_From_Source
-- This flag is on for any nodes built by the scanner or parser from
-- the source program, and off for any nodes built by the analyzer or
-- expander. It indicates that a node comes from the original source.
-- This flag is defined in Atree.
-- Has_Dynamic_Length_Check and Has_Dynamic_Range_Check also appear on
-- all nodes. They are fully described in the next section.
------------------------------------
-- 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.
-- ABE_Is_Certain (Flag18-Sem)
-- This flag is set in an instantiation node or a call node is
-- determined to be sure to raise an ABE. This is used to trigger
-- special handling of such cases, particularly in the instantiation
-- case where we avoid instantiating the body if this flag is set.
-- This flag is also present in an N_Formal_Package_Declaration_Node
-- since formal package declarations are treated like instantiations,
-- but it is always set to False in this context.
-- Accept_Handler_Records (List5-Sem)
-- 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 (Elist2-Sem)
-- 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 treatement is the generation of the
-- associated_final_chain.
-- Actions (List1-Sem)
-- 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 (Node3-Sem)
-- 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.
-- Acts_As_Spec (Flag4-Sem)
-- A flag set in the N_Subprogram_Body node for a subprogram body
-- which is acting as its own spec. This flag also appears in the
-- compilation unit node at the library level for such a subprogram
-- (see further description in spec of Lib package).
-- Aggregate_Bounds (Node3-Sem)
-- Present in array N_Aggregate nodes. If the aggregate contains
-- component associations this field points to an N_Range node whose
-- bounds give the lowest and highest discrete choice values. If the
-- named aggregate contains a dynamic or null choice this field is
-- empty. If the aggregate contains positional elements this field
-- points to an N_Integer_Literal node giving the number of positional
-- elements. Note that if the aggregate contains positional elements
-- and an other choice the N_Integer_Literal only accounts for the
-- number of positional elements.
-- All_Others (Flag11-Sem)
-- Present in an N_Others_Choice node. This flag is set in the case
-- of 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.
-- Assignment_OK (Flag15-Sem)
-- 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 initialzation 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).
-- Associated_Node (Node4-Sem)
-- 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.
-- At_End_Proc (Node1)
-- 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 (Flag6-Sem)
-- 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. Note that 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 is required.
-- Body_To_Inline (Node3-Sem)
-- 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 en-
-- tity 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 (Flag13-Sem)
-- 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 a
-- 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 (Flag5-Sem)
-- A flag present in the N_Return_Statement_Node. It 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.
-- Check_Address_Alignment (Flag11-Sem)
-- 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.
-- Compile_Time_Known_Aggregate (Flag18-Sem)
-- 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 Gigi without any expansion.
-- See Sem_Aggr for the specific conditions under which an aggregate
-- has this flag set. See also the flag Static_Processing_OK.
-- Condition_Actions (List3-Sem)
-- 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.
-- Controlling_Argument (Node1-Sem)
-- 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 controlling tag for the call. For
-- Procedure calls, the Controlling_Argument is one of the actuals.
-- For a 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.
-- Conversion_OK (Flag14-Sem)
-- 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 the Enum_Rep,
-- Fixed_Value and Integer_Value attributes, 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 a direct conversion of the underlying integer
-- result, with no regard to the small operand.
-- Corresponding_Body (Node5-Sem)
-- 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_Generic_Association (Node5-Sem)
-- 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 to
-- a generic_association which is the original parent of the expression
-- or name appearing in the declaration. This simplifies ASIS queries.
-- Corresponding_Integer_Value (Uint4-Sem)
-- 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 (Node5-Sem)
-- 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.
-- Corresponding_Stub (Node3-Sem)
-- 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 (Node5-Sem)
-- This field is present in an N_Variant node, It references the entity
-- for the discriminant checking function for the variant.
-- Debug_Statement (Node3)
-- This field is present in an N_Pragma node. It is used only for
-- a Debug pragma or pragma Assert with a second parameter. The
-- parameter is of the form of an expression, as required by the
-- pragma syntax, but is actually a procedure call. To simplify
-- semantic processing, the parser creates a copy of the argument
-- rearranged into a procedure call statement and places it in the
-- Debug_Statement field. Note that this field is considered a
-- syntactic field, since it is created by the parser.
-- Default_Expression (Node5-Sem)
-- 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.
-- Delay_Finalize_Attach (Flag14-Sem)
-- This flag is present in an N_Object_Declaration node. If it is set,
-- then in the case of a controlled type being declared and initialized,
-- the normal code for attaching the result to the appropriate local
-- finalization list is suppressed. This is used for functions that
-- return controlled types without using the secondary stack, where
-- it is the caller who must do the attachment.
-- Discr_Check_Funcs_Built (Flag11-Sem)
-- 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_Accessibility_Check (Flag13-Sem)
-- This flag is set on N_Parameter_Specification nodes to indicate
-- that an accessibility check is required for the parameter. It is
-- not yet decided who takes care of this check (TBD ???).
-- Do_Discriminant_Check (Flag13-Sem)
-- 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.
-- Do_Division_Check (Flag13-Sem)
-- This flag is set on a division operator (/ mod rem) to indicate
-- that a zero divide check is required. The actual check is dealt
-- with by the backend (all the front end does is to set the flag).
-- Do_Length_Check (Flag4-Sem)
-- 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 (Flag17-Sem)
-- This flag is set on an operator where an overflow check is required
-- on the operation. The actual check is dealt with by the backend
-- (all the front end does is to set the flag). The other cases where
-- this flag is used is on a Type_Conversion node and for attribute
-- reference 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. The only attribute references which use this flag are
-- Pred and Succ, where it means that the result should be checked
-- for going outside the base range.
-- Do_Range_Check (Flag9-Sem)
-- 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 limited to
-- 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.
-- 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 (Flag17-Sem)
-- 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
-- prolog. 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.
-- Do_Tag_Check (Flag13-Sem)
-- This flag is set on an N_Assignment_Statement, N_Function_Call,
-- N_Procedure_Call_Statement, N_Type_Conversion or N_Return_Statememt
-- node to indicate that the tag check can be suppressed. It is not
-- yet decided how this flag is used (TBD ???).
-- Elaborate_Present (Flag4-Sem)
-- This flag is set in the N_With_Clause node to indicate that a
-- pragma Elaborate pragma appears for the with'ed units.
-- Elaborate_All_Present (Flag15-Sem)
-- This flag is set in the N_With_Clause node to indicate that a
-- pragma Elaborate_All pragma appears for the with'ed units.
-- Elaboration_Boolean (Node2-Sem)
-- This field is present in function and procedure specification
-- nodes. If set, it points to the entity for a Boolean flag that
-- must be tested for certain calls to check for access before
-- elaboration. See body of Sem_Elab for further details. This
-- field is Empty if no elaboration boolean is required.
-- Else_Actions (List3-Sem)
-- This field is present in conditional 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 conditional 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 (Node2-Sem)
-- 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 (Node4-Sem)
-- Appears in all direct names (identifier, character literal,
-- operator symbol), as well as expanded names, and attributes that
-- denote entities, such as 'Class. Points to the entity for the
-- corresponding defining occurrence. Set after name resolution.
-- In the case of identifiers in a WITH list, the corresponding
-- defining occurrence is in a separately compiled file, and this
-- pointer must be set using the library Load procedure. Note that
-- 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 that 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.
-- Entity_Or_Associated_Node (Node4-Sem)
-- A synonym for both Entity and Asasociated_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 (Node5-Sem)
-- 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 (Flag11-Sem)
-- 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).
-- Expansion_Delayed (Flag11-Sem)
-- 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 aggregates,
-- 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 sub-component.
-- First_Inlined_Subprogram (Node3-Sem)
-- 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 (Node4-Sem)
-- 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 (Node2-Sem)
-- 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 (Node5-Sem)
-- 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 (Flag11-Sem)
-- A flag present in type conversion nodes. This is used for float
-- to integer conversions where truncation is required rather than
-- rounding. Note that Gigi does not handle type conversions from real
-- to integer with rounding (see Expand_N_Type_Conversion).
-- Forwards_OK (Flag5-Sem)
-- 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. Note that 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 is required.
-- From_At_Mod (Flag4-Sem)
-- 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.
-- Generic_Parent (Node5-Sem)
-- 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 is also defined for the renaming
-- declarations and object declarations created for the actuals in an
-- instantiation. The generic parent of such a declaration is the
-- corresponding generic association in the Instantiation node.
-- Generic_Parent_Type (Node4-Sem)
-- 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 (Node2-Sem)
-- 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_Dynamic_Length_Check (Flag10-Sem)
-- This flag is present on all 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_Dynamic_Range_Check (Flag12-Sem)
-- This flag is present on all nodes. It is set to indicate that one
-- of the routines in unit Checks has generated a range check action
-- which has been inserted at the flagged node. This is used to avoid
-- the generation of duplicate checks.
-- Has_No_Elaboration_Code (Flag17-Sem)
-- 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_Priority_Pragma (Flag6-Sem)
-- A flag present in N_Subprogram_Body, N_Task_Definition and
-- N_Protected_Definition nodes to flag the presence of either
-- a Priority or Interrupt_Priority pragma in the declaration
-- sequence (public or private in the task and protected cases)
-- Has_Private_View (Flag11-Sem)
-- 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_Storage_Size_Pragma (Flag5-Sem)
-- A flag present in an N_Task_Definition node to flag the presence
-- of a Storage_Size pragma
-- Has_Task_Info_Pragma (Flag7-Sem)
-- A flag present in an N_Task_Definition node to flag the presence
-- of a Task_Info pragma. Used to detect duplicate pragmas.
-- Has_Task_Name_Pragma (Flag8-Sem)
-- A flag present in N_Task_Definition nodes to flag the presence
-- of a Task_Name pragma in the declaration sequence for the task.
-- Has_Wide_Character (Flag11-Sem)
-- Present in string literals, set if any wide character (i.e. a
-- character code outside the Character range) appears in the string.
-- Hidden_By_Use_Clause (Elist4-Sem)
-- 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 (Flag16-Sem)
-- This flag is set in the N_With_Clause node that is implicitly
-- generated for runtime units that are loaded by the expander, and
-- also for package System, if it is loaded implicitly by a use of
-- the 'Address or 'Tag attribute
-- Includes_Infinities (Flag11-Sem)
-- 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 legtitimately 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.
-- Instance_Spec (Node5-Sem)
-- 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_Asynchronous_Call_Block (Flag7-Sem)
-- A flag set in a Block_Statement node to indicate that it is the
-- expansion of an asynchronous entry call. Such a block needs a
-- cleanup handler to assure that the call is cancelled.
-- Is_Component_Left_Opnd (Flag13-Sem)
-- Is_Component_Right_Opnd (Flag14-Sem)
-- 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 (Flag16-Sem)
-- This flag is set on in 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_In_Discriminant_Check (Flag11-Sem)
-- 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 disriminant check may be optimized away!)
-- Is_Machine_Number (Flag11-Sem)
-- 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 (Flag16-Sem)
-- 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
-- suppress any warnings that would otherwise be issued inside the
-- loop since they are probably not useful.
-- Is_Power_Of_2_For_Shift (Flag13-Sem)
-- A flag present only in N_Op_Expon nodes. It is set when the
-- exponentiation is of the forma 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_Overloaded (Flag5-Sem)
-- 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_Protected_Subprogram_Body (Flag7-Sem)
-- A flag set in a Subprogram_Body block to indicate that it is the
-- implemenation of a protected subprogram. Such a body needs a
-- cleanup handler to make sure that the associated protected object
-- is unlocked when the subprogram completes.
-- Is_Static_Expression (Flag6-Sem)
-- Indicates that an expression is a static expression (RM 4.9). See
-- spec of package Sem_Eval for full details on the use of this flag.
-- Is_Subprogram_Descriptor (Flag16-Sem)
-- 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 (Flag6-Sem)
-- 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_Unactivted_Tasks to complete any tasks that have been
-- allocated but not activated when the allocator completes abnormally.
-- Is_Task_Master (Flag5-Sem)
-- 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).
-- Itype (Node1-Sem)
-- 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 (Flag11-Sem)
-- 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 (Node2-Sem)
-- 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. This is not currently used in the compiler
-- itself, but it is useful in the implementation of ASIS queries.
-- Library_Unit (Node4-Sem)
-- In a stub node, the Library_Unit field points to the compilation unit
-- node of the corresponding subunit.
--
-- In a with clause node, the Library_Unit field points to the spec
-- of the with'ed unit.
--
-- In a compilation unit node, the use of this field depends on
-- the unit type:
--
-- For a subprogram body, the Library_Unit field points to the
-- compilation unit node of the corresponding spec, unless
-- Acts_As_Spec is set, in which case it points to itself.
--
-- For a package body, the Library_Unit field points to the
-- compilation unit node of the corresponding spec.
--
-- For a subprogram spec to which pragma Inline applies, the
-- Library_Unit field points to the compilation unit node of
-- the corresponding body, if inlining is active.
--
-- For a generic declaration, the Library_Unit field points
-- to the compilation unit node of the corresponding generic body.
--
-- For a subunit, the Library_Unit field points to the compilation
-- unit node of the parent body.
--
-- Note that this field is not used to hold the parent pointer for a
-- 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.
-- Loop_Actions (List2-Sem)
-- 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 (Flag18-Sem)
-- Present in With_Clauses and in package specifications. If set on a
-- 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.
-- Must_Be_Byte_Aligned (Flag14-Sem)
-- 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 (Flag8-Sem)
-- 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 (Node2-Sem)
-- 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_Named_Actual (Node4-Sem)
-- Present in parameter association node. 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_Rep_Item (Node4-Sem)
-- Present in pragma nodes and attribute definition nodes. Used to
-- link representation items that apply to an entity. See description
-- of First_Rep_Item field in Einfo for full details.
-- Next_Use_Clause (Node3-Sem)
-- 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 (Flag7-Sem)
-- Present in N_Assignment_Statement to indicate that no finalize nor
-- nor adjust should take place on this assignment eventhough the rhs
-- is controlled. This is used in init procs and aggregate expansions
-- where the generated assignments are more initialisations than real
-- assignments.
-- No_Elaboration_Check (Flag14-Sem)
-- 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 (Flag8-Sem)
-- 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 (Flag13-Sem)
-- Present in N_Object_Declaration & N_Allocator to indicate
-- that the object must not be initialized (by Initialize or a
-- 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)
-- No_Truncation (Flag17-Sem)
-- 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 a
-- 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.
-- OK_For_Stream (Flag4-Sem)
-- Present in N_Attribute_Definition clauses for stream attributes. If
-- set, indicates that the attribute is permitted even though the type
-- involved is a limited type. In the case of a protected type, the
-- result is to stream all components (including discriminants) in
-- lexical order. For other limited types, the effect is simply to
-- use the corresponding stream routine for the full type. This flag
-- is used for internally generated code, where the streaming of these
-- types is required, even though not normally allowed by the language.
-- Original_Discriminant (Node2-Sem)
-- 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 (Node2-Sem)
-- 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 (ASIS problem).
-- Others_Discrete_Choices (List1-Sem)
-- 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.
-- Parameter_List_Truncated (Flag17-Sem)
-- Present in N_Function_Call and N_Procedure_Call_Statement nodes.
-- Set (for OpenVMS ports of GNAT only) if the parameter list is
-- truncated as a result of a First_Optional_Parameter specification
-- in an Import_Function, Import_Procedure, or Import_Valued_Procedure
-- pragma. The truncation is done by the expander by removing trailing
-- parameters from the argument list, in accordance with the set of
-- rules allowing such parameter removal. In particular, parameters
-- can be removed working from the end of the parameter list backwards
-- up to and including the entry designated by First_Optional_Parameter
-- in the Import pragma. Parameters can be removed if they are implicit
-- and the default value is a known-at-compile-time value, including
-- the use of the Null_Parameter attribute, or if explicit parameter
-- values are present that match the corresponding defaults.
-- Parent_Spec (Node4-Sem)
-- 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).
-- Present_Expr (Uint3-Sem)
-- 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. Give 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 ASIS processing (data decomposition annex)
-- to determine if a field is present or not.
-- Print_In_Hex (Flag13-Sem)
-- 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 (Node4-Sem)
-- Present in N_Allocator. N_Free_Statement, and N_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_Return_Statement
-- (for allocating the return value), and for the Deallocate procedure
-- in the case of N_Free_Statement.
-- Raises_Constraint_Error (Flag7-Sem)
-- Set on an expression whose evaluation will definitely fail a
-- constraint error check. In the case of static expressions, this
-- flag must be set accurately (and if it is set, the expression is
-- typically illegal unless it appears as a non-elaborated branch of
-- a short-circuit form). For a non-static expression, this flag may
-- be set whenever an expression (e.g. an aggregate) is known to raise
-- constraint error. If set, the expression definitely will raise CE
-- if elaborated at runtime. If not set, the expression may or may
-- not raise CE. In other words, on static expressions, the flag is
-- set accurately, on non-static expressions it is set conservatively.
-- Redundant_Use (Flag13-Sem)
-- A flag 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).
-- Return_Type (Node2-Sem)
-- Present in N_Return_Statement node. For a procedure, this is set
-- to Standard_Void_Type. For a function it references the entity
-- for the returned type.
-- Rounded_Result (Flag18-Sem)
-- 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, conersion and multiplication operations.
-- Scope (Node3-Sem)
-- 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 (Flag4-Sem)
-- 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 (Node1-Sem)
-- 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.
-- Static_Processing_OK (Flag4-Sem)
-- Present in N_Aggregate nodes. When the Compile_Time_Known_Aggregate
-- flag is set, the full value of the aggregate can be determined at
-- compile time and the aggregate can be passed as is to the back-end.
-- In this event it is irrelevant whether this flag is set or not.
-- However, if the Compile_Time_Known_Aggregate flag is not set but
-- Static_Processing_OK is set, the aggregate can (but need not) be
-- converted into a compile time known aggregate by the expander.
-- See Sem_Aggr for the specific conditions under which an aggregate
-- has its Static_Processing_OK flag set.
-- Storage_Pool (Node1-Sem)
-- Present in N_Allocator, N_Free_Statement and N_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 a function. Empty indicates that the global default
-- default pool is to be used. Note that in the case of a return
-- statement, this field is set only if the function returns a
-- value of a type whose size is not known at compile time on the
-- secondary stack. It is never set on targets for which the target
-- parameter Targparm.Functions_Return_By_DSP_On_Target is True.
-- Target_Type (Node2-Sem)
-- 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.
-- Task_Body_Procedure (Node2-Sem)
-- Present in task type declaration nodes. Points to the entity for
-- the task body procedure (as further described in Exp_Ch9, task
-- bodies are expanded into procedures). A convenient function to
-- retrieve this field is Sem_Util.Get_Task_Body_Procedure.
-- Then_Actions (List3-Sem)
-- This field is present in conditional 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 conditional expressions, we have to be sure that the
-- actions 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.
-- Treat_Fixed_As_Integer (Flag14-Sem)
-- This flag appears in operator nodes for divide, multiply, mod and
-- rem on fixed-point operands. It indicates that the operands are
-- to be treated as integer values, ignoring small values. This flag
-- is only set as a result of expansion of fixed-point operations.
-- Typically a fixed-point multplication in the source generates
-- subsidiary multiplication and division operations that work with
-- the underlying integer values and have this flag set. Note that
-- this flag is not needed on other arithmetic operations (add, neg,
-- subtract etc) since in these cases it is always the case that fixed
-- is treated as integer. The Etype field MUST be set if this flag
-- is set. The analyzer knows to leave such nodes alone, and whoever
-- makes them must set the correct Etype value.
-- TSS_Elist (Elist3-Sem)
-- 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.
-- Unreferenced_In_Spec (Flag7-Sem)
-- 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)
-- Was_Originally_Stub (Flag13-Sem)
-- This flag is set in the node for a proper body that replaces a
-- 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_Tree here because of the case of
-- nested instantiations where the substituted node can be copied.
-- Zero_Cost_Handling (Flag5-Sem)
-- This flag is set in all handled sequence of statement and exception
-- handler nodes if eceptions are to be handled using the zero-cost
-- mechanism (see Ada.Exceptions and System.Exceptions in files
-- a-except.ads/adb and s-except.ads for full details). What gigi
-- needs to do for such a handler is simply to put the code in the
-- handler somewhere. The front end has generated all necessary labels.
--------------------------------------------------
-- 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 (Name1) contains the Name_Id for the identifier
-- Entity (Node4-Sem)
-- Associated_Node (Node4-Sem)
-- Original_Discriminant (Node2-Sem)
-- Redundant_Use (Flag13-Sem)
-- Has_Private_View (Flag11-Sem) (set in generic units)
-- 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].
-- N_Integer_Literal
-- Sloc points to literal
-- Original_Entity (Node2-Sem) If not Empty, holds Named_Number that
-- has been constant-folded into its literal value.
-- Intval (Uint3) contains integer value of literal
-- plus fields for expression
-- Print_In_Hex (Flag13-Sem)
-- N_Real_Literal
-- Sloc points to literal
-- Original_Entity (Node2-Sem) If not Empty, holds Named_Number that
-- has been constant-folded into its literal value.
-- Realval (Ureal3) contains real value of literal
-- Corresponding_Integer_Value (Uint4-Sem)
-- Is_Machine_Number (Flag11-Sem)
-- 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 (Name1) contains the Name_Id for the identifier
-- Char_Literal_Value (Char_Code2) contains the literal value
-- Entity (Node4-Sem)
-- Associated_Node (Node4-Sem)
-- Has_Private_View (Flag11-Sem) set in generic units.
-- plus fields for expression
-- Note: the Entity field will be missing (and 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.
-- N_String_Literal
-- Sloc points to literal
-- Strval (Str3) contains Id of string value
-- Has_Wide_Character (Flag11-Sem)
-- 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
-- Chars (Name1) identifier name from pragma identifier
-- Pragma_Argument_Associations (List2) (set to No_List if none)
-- Debug_Statement (Node3) (set to Empty if not Debug, Assert)
-- Next_Rep_Item (Node4-Sem)
--------------------------------------
-- 2.8 Pragma Argument Association --
--------------------------------------
-- PRAGMA_ARGUMENT_ASSOCIATION ::=
-- [pragma_argument_IDENTIFIER =>] NAME
-- | [pragma_argument_IDENTIFIER =>] EXPRESSION
-- N_Pragma_Argument_Association
-- Sloc points to first token in association
-- Chars (Name1) (set to No_Name if no pragma argument identifier)
-- Expression (Node3)
------------------------
-- 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
-- deliberate layed 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 (Name1) contains the Name_Id for the identifier
-- Next_Entity (Node2-Sem)
-- Scope (Node3-Sem)
-- Etype (Node5-Sem)
-----------------------------
-- 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;
-- | 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 (Node1)
-- Discriminant_Specifications (List4) (set to No_List if none)
-- Type_Definition (Node3)
-- Discr_Check_Funcs_Built (Flag11-Sem)
----------------------------
-- 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
--------------------------------
-- 3.2.2 Subtype Declaration --
--------------------------------
-- SUBTYPE_DECLARATION ::=
-- subtype DEFINING_IDENTIFIER is SUBTYPE_INDICATION;
-- 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 (Node1)
-- Subtype_Indication (Node5)
-- Generic_Parent_Type (Node4-Sem) (set for an actual derived type).
-- Exception_Junk (Flag11-Sem)
-------------------------------
-- 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: 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 (Node4)
-- Constraint (Node3)
-- Etype (Node5-Sem)
-- Must_Not_Freeze (Flag8-Sem)
-- Note: Etype is a copy of the Etype field of the Subtype_Mark. The
-- reason for this redundancy is so that in a list of array index types,
-- the Etype can be uniformly accessed to determine the subscript type.
-- This means that no Itype is constructed for the actual subtype that
-- is created by the subtype indication. If such an Itype is required,
-- it is constructed in the context in which the indication appears.
-------------------------
-- 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]
-- SUBTYPE_INDICATION [:= EXPRESSION];
-- | DEFINING_IDENTIFIER_LIST : [aliased] [constant]
-- ARRAY_TYPE_DEFINITION [:= EXPRESSION];
-- | 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 two 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".
-- 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). It
-- also cannot be a reference to an object marked as a true constant
-- (Is_True_Constant flag set), where the object is itself initalized
-- with an aggregate. If necessary the front end must generate an
-- extra temporary (with Is_True_Constant set False), and initialize
-- this temporary as required (the temporary itself is not atomic).
-- N_Object_Declaration
-- Sloc points to first identifier
-- Defining_Identifier (Node1)
-- Aliased_Present (Flag4) set if ALIASED appears
-- Constant_Present (Flag17) set if CONSTANT appears
-- Object_Definition (Node4) subtype indication/array type definition
-- Expression (Node3) (set to Empty if not present)
-- Handler_List_Entry (Node2-Sem)
-- Corresponding_Generic_Association (Node5-Sem)
-- More_Ids (Flag5) (set to False if no more identifiers in list)
-- Prev_Ids (Flag6) (set to False if no previous identifiers in list)
-- No_Initialization (Flag13-Sem)
-- Assignment_OK (Flag15-Sem)
-- Exception_Junk (Flag11-Sem)
-- Delay_Finalize_Attach (Flag14-Sem)
-- Is_Subprogram_Descriptor (Flag16-Sem)
-------------------------------------
-- 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 (Node1)
-- Expression (Node3)
-- More_Ids (Flag5) (set to False if no more identifiers in list)
-- Prev_Ids (Flag6) (set to False if no previous identifiers in list)
----------------------------------
-- 3.4 Derived Type Definition --
----------------------------------
-- DERIVED_TYPE_DEFINITION ::=
-- [abstract] new parent_SUBTYPE_INDICATION [RECORD_EXTENSION_PART]
-- Note: ABSTRACT, record extension part 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 (Flag4)
-- Subtype_Indication (Node5)
-- Record_Extension_Part (Node3) (set to Empty if not present)
---------------------------
-- 3.5 Range Constraint --
---------------------------
-- RANGE_CONSTRAINT ::= range RANGE
-- N_Range_Constraint
-- Sloc points to RANGE
-- Range_Expression (Node4)
----------------
-- 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 (Node1)
-- High_Bound (Node2)
-- Includes_Infinities (Flag11)
-- 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 (List1) (Empty for CHARACTER or WIDE_CHARACTER)
-- End_Label (Node4) (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 deliberate layed out to match the 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 (Name1) contains the Name_Id for the identifier
-- Next_Entity (Node2-Sem)
-- Scope (Node3-Sem)
-- Etype (Node5-Sem)
------------------------------------
-- 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 (Node1)
-- High_Bound (Node2)
-----------------------------------------
-- 3.5.4 Unsigned Range Specification --
-----------------------------------------
-- MODULAR_TYPE_DEFINITION ::= mod static_EXPRESSION
-- N_Modular_Type_Definition
-- Sloc points to MOD
-- Expression (Node3)
---------------------------------
-- 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 (Node2)
-- Real_Range_Specification (Node4) (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 (Node1)
-- High_Bound (Node2)
-----------------------------------
-- 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
-- Note: the Delta_Expression and Real_Range_Specification fields
-- are set to Empty for fixed point types declared in Standard.
-- N_Ordinary_Fixed_Point_Definition
-- Sloc points to DELTA
-- Delta_Expression (Node3)
-- Real_Range_Specification (Node4)
-------------------------------------------
-- 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 (Node3)
-- Digits_Expression (Node2)
-- Real_Range_Specification (Node4) (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 (Node2)
-- Range_Constraint (Node4) (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 (List2)
-- Component_Definition (Node4)
-----------------------------------
-- 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 (List2)
-- Component_Definition (Node4)
--------------------------------------
-- 3.6 Discrete Subtype Definition --
--------------------------------------
-- DISCRETE_SUBTYPE_DEFINITION ::=
-- discrete_SUBTYPE_INDICATION | RANGE
-------------------------------
-- 3.6 Component Definition --
-------------------------------
-- COMPONENT_DEFINITION ::= [aliased] SUBTYPE_INDICATION
-- 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.
-- N_Component_Definition
-- Sloc points to ALIASED or to first token of subtype mark
-- Aliased_Present (Flag4)
-- Subtype_Indication (Node5)
-----------------------------
-- 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 : 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 (Node1)
-- Discriminant_Type (Node5) subtype mark or
-- access parameter definition
-- Expression (Node3) (set to Empty if no default expression)
-- More_Ids (Flag5) (set to False if no more identifiers in list)
-- Prev_Ids (Flag6) (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 (List1) 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 (List1) (always non-empty, since if no selector
-- names are present, this node is not used, see comment above)
-- Expression (Node3)
---------------------------------
-- 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 (Node4) (set to Empty if internally generated record)
-- Abstract_Present (Flag4)
-- Tagged_Present (Flag15)
-- Limited_Present (Flag17)
-- Component_List (Node1) empty in null record case
-- Null_Present (Flag13) set in null record case
-------------------------
-- 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 (List3)
-- Variant_Part (Node4) (set to Empty if no variant part)
-- Null_Present (Flag13)
-------------------------
-- 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]
-- 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 (Node1)
-- Component_Definition (Node4)
-- Expression (Node3) (set to Empty if no default expression)
-- More_Ids (Flag5) (set to False if no more identifiers in list)
-- Prev_Ids (Flag6) (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 (Node2)
-- Variants (List1)
--------------------
-- 3.8.1 Variant --
--------------------
-- VARIANT ::=
-- when DISCRETE_CHOICE_LIST =>
-- COMPONENT_LIST
-- N_Variant
-- Sloc points to WHEN
-- Discrete_Choices (List4)
-- Component_List (Node1)
-- Enclosing_Variant (Node2-Sem)
-- Present_Expr (Uint3-Sem)
-- Dcheck_Function (Node5-Sem)
---------------------------------
-- 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 (List1-Sem)
-- All_Others (Flag11-Sem)
----------------------------------
-- 3.9.1 Record Extension Part --
----------------------------------
-- RECORD_EXTENSION_PART ::= with RECORD_DEFINITION
-- Note: record extension parts are not permitted in Ada 83 mode
----------------------------------
-- 3.10 Access Type Definition --
----------------------------------
-- ACCESS_TYPE_DEFINITION ::=
-- ACCESS_TO_OBJECT_DEFINITION
-- | ACCESS_TO_SUBPROGRAM_DEFINITION
---------------------------------------
-- 3.10 Access To Object Definition --
---------------------------------------
-- ACCESS_TO_OBJECT_DEFINITION ::=
-- access [GENERAL_ACCESS_MODIFIER] SUBTYPE_INDICATION
-- N_Access_To_Object_Definition
-- Sloc points to ACCESS
-- All_Present (Flag15)
-- Subtype_Indication (Node5)
-- Constant_Present (Flag17)
-----------------------------------
-- 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
-- access [protected] procedure PARAMETER_PROFILE
-- | 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
-- Protected_Present (Flag15)
-- Parameter_Specifications (List3) (set to No_List if no formal part)
-- Subtype_Mark (Node4) result subtype
-- N_Access_Procedure_Definition
-- Sloc points to ACCESS
-- Protected_Present (Flag15)
-- Parameter_Specifications (List3) (set to No_List if no formal part)
-----------------------------
-- 3.10 Access Definition --
-----------------------------
-- ACCESS_DEFINITION ::= access SUBTYPE_MARK
-- N_Access_Definition
-- Sloc points to ACCESS
-- Subtype_Mark (Node4)
-----------------------------------------
-- 3.10.1 Incomplete Type Declaration --
-----------------------------------------
-- INCOMPLETE_TYPE_DECLARATION ::=
-- type DEFINING_IDENTIFIER [DISCRIMINANT_PART];
-- N_Incomplete_Type_Declaration
-- Sloc points to TYPE
-- Defining_Identifier (Node1)
-- Discriminant_Specifications (List4) (set to No_List if no
-- discriminant part, or if the discriminant part is an
-- unknown discriminant part)
-- Unknown_Discriminants_Present (Flag13) set if (<>) discriminant
----------------------------
-- 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 (Node3)
-- 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 (Node3)
-- Expressions (List1)
-- 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 (Node3)
-- Discrete_Range (Node4)
-- 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 period
-- Prefix (Node3)
-- Selector_Name (Node2)
-- Associated_Node (Node4-Sem)
-- Do_Discriminant_Check (Flag13-Sem)
-- Is_In_Discriminant_Check (Flag11-Sem)
-- 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.
-- The flag OK_For_Stream is used in generated code to indicate that
-- a stream attribute is permissible for a limited type, and results
-- in the use of the stream attribute for the underlying full type,
-- or in the case of a protected type, the components (including any
-- disriminants) 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.
-- 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 (Node3)
-- Attribute_Name (Name2) identifier name from attribute designator
-- Expressions (List1) (set to No_List if no associated expressions)
-- Entity (Node4-Sem) used if the attribute yields a type
-- Associated_Node (Node4-Sem)
-- Do_Overflow_Check (Flag17-Sem)
-- Redundant_Use (Flag13-Sem)
-- OK_For_Stream (Flag4-Sem)
-- Must_Be_Byte_Aligned (Flag14)
-- plus fields for expression
---------------------------------
-- 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 (List1) (set to No_List if none or null record case)
-- Component_Associations (List2) (set to No_List if none)
-- Null_Record_Present (Flag17)
-- Aggregate_Bounds (Node3-Sem)
-- Associated_Node (Node4-Sem)
-- Static_Processing_OK (Flag4-Sem)
-- Compile_Time_Known_Aggregate (Flag18-Sem)
-- Expansion_Delayed (Flag11-Sem)
-- 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: 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 all 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 runtime, and
-- providing that the aggregate is presented in fully named form.
----------------------------------------------
-- 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 (List1)
-- Loop_Actions (List2-Sem)
-- Expression (Node3)
-- Box_Present (Flag15)
-- 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 Ada0Y (AI-287).
------------------------------------
-- 4.3.1 Commponent 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 (Node3)
-- Associated_Node (Node4-Sem)
-- Expressions (List1) (set to No_List if none or null record case)
-- Component_Associations (List2) (set to No_List if none)
-- Null_Record_Present (Flag17)
-- Expansion_Delayed (Flag11-Sem)
-- 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
-- See Record_Component_Association (4.3.1) for node structure
--------------------------------------------------
-- 4.4 Expression/Relation/Term/Factor/Primary --
--------------------------------------------------
-- EXPRESSION ::=
-- RELATION {and RELATION} | RELATION {and then RELATION}
-- | RELATION {or RELATION} | RELATION {or else RELATION}
-- | RELATION {xor RELATION}
-- RELATION ::=
-- SIMPLE_EXPRESSION [RELATIONAL_OPERATOR SIMPLE_EXPRESSION]
-- | SIMPLE_EXPRESSION [not] in RANGE
-- | SIMPLE_EXPRESSION [not] in SUBTYPE_MARK
-- 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
-- consistuent components of an expression (e.g. identifier is
-- an example of an expression).
------------------
-- 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 accomodated by this count, then the count is simply left
-- at the maximum value. This means that there are some pathalogical
-- 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 (Node2)
-- Right_Opnd (Node3)
-- Actions (List1-Sem)
-- plus fields for expression
-- N_Or_Else
-- Sloc points to OR of OR ELSE
-- Left_Opnd (Node2)
-- Right_Opnd (Node3)
-- Actions (List1-Sem)
-- 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 RANGE
-- | SIMPLE_EXPRESSION [not] in 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 prepared to deal with, and diagnose
-- a simple expression other than a name for the right operand.
-- This simplifies error recovery in the parser.
-- N_In
-- Sloc points to IN
-- Left_Opnd (Node2)
-- Right_Opnd (Node3)
-- plus fields for expression
-- N_Not_In
-- Sloc points to NOT of NOT IN
-- Left_Opnd (Node2)
-- Right_Opnd (Node3)
-- 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
-- Sprint syntax if Treat_Fixed_As_Integer is set:
-- x #* y
-- x #/ y
-- x #mod y
-- x #rem y
-- Gigi restriction: For * / mod rem with fixed-point operands, Gigi
-- will only be given nodes with the Treat_Fixed_As_Integer flag set.
-- 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 (Flag4-Sem)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Or
-- Sloc points to OR
-- Do_Length_Check (Flag4-Sem)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Xor
-- Sloc points to XOR
-- Do_Length_Check (Flag4-Sem)
-- 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 (Flag13-Sem)
-- Is_Component_Right_Opnd (Flag14-Sem)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Multiply
-- Sloc points to *
-- Treat_Fixed_As_Integer (Flag14-Sem)
-- Rounded_Result (Flag18-Sem)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Divide
-- Sloc points to /
-- Treat_Fixed_As_Integer (Flag14-Sem)
-- Do_Division_Check (Flag13-Sem)
-- Rounded_Result (Flag18-Sem)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Mod
-- Sloc points to MOD
-- Treat_Fixed_As_Integer (Flag14-Sem)
-- Do_Division_Check (Flag13-Sem)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Rem
-- Sloc points to REM
-- Treat_Fixed_As_Integer (Flag14-Sem)
-- Do_Division_Check (Flag13-Sem)
-- plus fields for binary operator
-- plus fields for expression
-- N_Op_Expon
-- Is_Power_Of_2_For_Shift (Flag13-Sem)
-- Sloc points to **
-- 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 only see fixed
-- point operands if the Treat_Fixed_As_Integer flag is set and will
-- thus treat these nodes in identical manner, ignoring small values.
--------------------------
-- 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.
-- 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 (Node4)
-- Expression (Node3)
-- Do_Tag_Check (Flag13-Sem)
-- Do_Length_Check (Flag4-Sem)
-- Do_Overflow_Check (Flag17-Sem)
-- Float_Truncate (Flag11-Sem)
-- Rounded_Result (Flag18-Sem)
-- Conversion_OK (Flag14-Sem)
-- 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 (Node4)
-- Expression (Node3) expression or aggregate
-- plus fields for expression
--------------------
-- 4.8 Allocator --
--------------------
-- ALLOCATOR ::=
-- new SUBTYPE_INDICATION | new QUALIFIED_EXPRESSION
-- Sprint syntax (when storage pool present)
-- new xxx (storage_pool = pool)
-- N_Allocator
-- Sloc points to NEW
-- Expression (Node3) subtype indication or qualified expression
-- Storage_Pool (Node1-Sem)
-- Procedure_To_Call (Node4-Sem)
-- No_Initialization (Flag13-Sem)
-- Do_Storage_Check (Flag17-Sem)
-- plus fields for expression
---------------------------------
-- 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 genmerator
-- 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
-- | 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
-- | ACCEPT_STATEMENT | SELECT_STATEMENT
-------------------------
-- 5.1 Null Statement --
-------------------------
-- NULL_STATEMENT ::= null;
-- N_Null_Statement
-- Sloc points to NULL
----------------
-- 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 (Node1) direct name of statement identifier
-- Exception_Junk (Flag11-Sem)
-------------------------------
-- 5.1 Statement Identifier --
-------------------------------
-- STATEMENT_INDENTIFIER ::= 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 (Node2)
-- Expression (Node3)
-- Do_Tag_Check (Flag13-Sem)
-- Do_Length_Check (Flag4-Sem)
-- Forwards_OK (Flag5-Sem)
-- Backwards_OK (Flag6-Sem)
-- No_Ctrl_Actions (Flag7-Sem)
-- 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). It
-- also cannot be a reference to an object marked as a true constant
-- (Is_True_Constant flag set), where the object is itself initalized
-- with an aggregate. If necessary the front end must generate an
-- extra temporary (with Is_True_Constant set False), and initialize
-- this temporary as required (the temporary itself is not atomic).
-----------------------
-- 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 (Node1)
-- Then_Statements (List2)
-- Elsif_Parts (List3) (set to No_List if none present)
-- Else_Statements (List4) (set to No_List if no else part present)
-- End_Span (Uint5) (set to No_Uint if expander generated)
-- N_Elsif_Part
-- Sloc points to ELSIF
-- Condition (Node1)
-- Then_Statements (List2)
-- Condition_Actions (List3-Sem)
--------------------
-- 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 (Node3)
-- Alternatives (List4)
-- End_Span (Uint5) (set to No_Uint if expander generated)
-------------------------------------
-- 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 (List4)
-- Statements (List3)
-------------------------
-- 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 (Node1) loop identifier (set to Empty if no identifier)
-- Iteration_Scheme (Node2) (set to Empty if no iteration scheme)
-- Statements (List3)
-- End_Label (Node4)
-- Has_Created_Identifier (Flag15)
-- Is_Null_Loop (Flag16)
--------------------------
-- 5.5 Iteration Scheme --
--------------------------
-- ITERATION_SCHEME ::=
-- while CONDITION | for LOOP_PARAMETER_SPECIFICATION
-- 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.
-- N_Iteration_Scheme
-- Sloc points to WHILE or FOR
-- Condition (Node1) (set to Empty if FOR case)
-- Condition_Actions (List3-Sem)
-- Loop_Parameter_Specification (Node4) (set to Empty if WHILE case)
---------------------------------------
-- 5.5 Loop parameter specification --
---------------------------------------
-- LOOP_PARAMETER_SPECIFICATION ::=
-- DEFINING_IDENTIFIER in [reverse] DISCRETE_SUBTYPE_DEFINITION
-- N_Loop_Parameter_Specification
-- Sloc points to first identifier
-- Defining_Identifier (Node1)
-- Reverse_Present (Flag15)
-- Discrete_Subtype_Definition (Node4)
--------------------------
-- 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 in the implicit label declaration which occurs in
-- the innermost enclosing block.
-- Note: there is always a block statement identifier present in
-- the tree, even if none was given in the source. In the case where
-- no block identifier is given in the source, the parser creates
-- a name of the form _Block_n, where n is a decimal integer (the
-- two underlines ensure that the block 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
-- blocks constructed by the expander, and the semantic analyzer
-- creates and supplies dummy names for the blocks).
-- N_Block_Statement
-- Sloc points to DECLARE or BEGIN
-- Identifier (Node1) block direct name (set to Empty if not present)
-- Declarations (List2) (set to No_List if no DECLARE part)
-- Handled_Statement_Sequence (Node4)
-- Is_Task_Master (Flag5-Sem)
-- Activation_Chain_Entity (Node3-Sem)
-- Has_Created_Identifier (Flag15)
-- Is_Task_Allocation_Block (Flag6)
-- Is_Asynchronous_Call_Block (Flag7)
-------------------------
-- 5.7 Exit Statement --
-------------------------
-- EXIT_STATEMENT ::= exit [loop_NAME] [when CONDITION];
-- 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.
-- N_Exit_Statement
-- Sloc points to EXIT
-- Name (Node2) (set to Empty if no loop name present)
-- Condition (Node1) (set to Empty if no when part present)
-------------------------
-- 5.9 Goto Statement --
-------------------------
-- GOTO_STATEMENT ::= goto label_NAME;
-- N_Goto_Statement
-- Sloc points to GOTO
-- Name (Node2)
-- Exception_Junk (Flag11-Sem)
---------------------------------
-- 6.1 Subprogram Declaration --
---------------------------------
-- SUBPROGRAM_DECLARATION ::= SUBPROGRAM_SPECIFICATION;
-- N_Subprogram_Declaration
-- Sloc points to FUNCTION or PROCEDURE
-- Specification (Node1)
-- Body_To_Inline (Node3-Sem)
-- Corresponding_Body (Node5-Sem)
-- Parent_Spec (Node4-Sem)
------------------------------------------
-- 6.1 Abstract Subprogram Declaration --
------------------------------------------
-- ABSTRACT_SUBPROGRAM_DECLARATION ::=
-- SUBPROGRAM_SPECIFICATION is abstract;
-- N_Abstract_Subprogram_Declaration
-- Sloc points to ABSTRACT
-- Specification (Node1)
-----------------------------------
-- 6.1 Subprogram Specification --
-----------------------------------
-- SUBPROGRAM_SPECIFICATION ::=
-- procedure DEFINING_PROGRAM_UNIT_NAME PARAMETER_PROFILE
-- | 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 (Node1) (the designator)
-- Elaboration_Boolean (Node2-Sem)
-- Parameter_Specifications (List3) (set to No_List if no formal part)
-- Subtype_Mark (Node4) for return type
-- Generic_Parent (Node5-Sem)
-- N_Procedure_Specification
-- Sloc points to PROCEDURE
-- Defining_Unit_Name (Node1)
-- Elaboration_Boolean (Node2-Sem)
-- Parameter_Specifications (List3) (set to No_List if no formal part)
-- Generic_Parent (Node5-Sem)
---------------------
-- 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 (Node2) holds the parent unit name. Note that this is always
-- non-Empty, since this node is only used for the case where a
-- parent library unit package name is present.
-- Identifier (Node1)
-- 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 (Node2) holds the parent unit name. Note that this is always
-- non-Empty, since this node is only used for the case where a
-- parent unit name is present.
-- Defining_Identifier (Node1)
--------------------------
-- 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 (Name1) contains the Name_Id for the operator symbol
-- Strval (Str3) Id of string value. This is used if the operator
-- symbol turns out to be a normal string after all.
-- Entity (Node4-Sem)
-- Associated_Node (Node4-Sem)
-- Has_Private_View (Flag11-Sem) set in generic units.
-- Etype (Node5-Sem)
-- 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 layed 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 (Name1) contains the Name_Id for the operator symbol
-- Next_Entity (Node2-Sem)
-- Scope (Node3-Sem)
-- Etype (Node5-Sem)
----------------------------
-- 6.1 Parameter Profile --
----------------------------
-- PARAMETER_PROFILE ::= [FORMAL_PART]
---------------------------------------
-- 6.1 Parameter and Result Profile --
---------------------------------------
-- PARAMETER_AND_RESULT_PROFILE ::= [FORMAL_PART] return SUBTYPE_MARK
-- 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 : MODE 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_Parameter_Specification
-- Sloc points to first identifier
-- Defining_Identifier (Node1)
-- In_Present (Flag15)
-- Out_Present (Flag17)
-- Parameter_Type (Node2) subtype mark or access definition
-- Expression (Node3) (set to Empty if no default expression present)
-- Do_Accessibility_Check (Flag13-Sem)
-- More_Ids (Flag5) (set to False if no more identifiers in list)
-- Prev_Ids (Flag6) (set to False if no previous identifiers in list)
-- Default_Expression (Node5-Sem)
---------------
-- 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 is
-- DECLARATIVE_PART
-- begin
-- HANDLED_SEQUENCE_OF_STATEMENTS
-- end [DESIGNATOR];
-- N_Subprogram_Body
-- Sloc points to FUNCTION or PROCEDURE
-- Specification (Node1)
-- Declarations (List2)
-- Handled_Statement_Sequence (Node4)
-- Activation_Chain_Entity (Node3-Sem)
-- Corresponding_Spec (Node5-Sem)
-- Acts_As_Spec (Flag4-Sem)
-- Bad_Is_Detected (Flag15) used only by parser
-- Do_Storage_Check (Flag17-Sem)
-- Has_Priority_Pragma (Flag6-Sem)
-- Is_Protected_Subprogram_Body (Flag7-Sem)
-- Is_Task_Master (Flag5-Sem)
-- Was_Originally_Stub (Flag13-Sem)
-----------------------------------
-- 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 (Node2) stores name or prefix
-- Parameter_Associations (List3) (set to No_List if no
-- actual parameter part)
-- First_Named_Actual (Node4-Sem)
-- Controlling_Argument (Node1-Sem) (set to Empty if not dispatching)
-- Do_Tag_Check (Flag13-Sem)
-- No_Elaboration_Check (Flag14-Sem)
-- Parameter_List_Truncated (Flag17-Sem)
-- ABE_Is_Certain (Flag18-Sem)
-- 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 descendent 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 (Node2) stores name or prefix
-- Parameter_Associations (List3) (set to No_List if no
-- actual parameter part)
-- First_Named_Actual (Node4-Sem)
-- Controlling_Argument (Node1-Sem) (set to Empty if not dispatching)
-- Do_Tag_Check (Flag13-Sem)
-- No_Elaboration_Check (Flag14-Sem)
-- Parameter_List_Truncated (Flag17-Sem)
-- ABE_Is_Certain (Flag18-Sem)
-- 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 (Node2) (always non-Empty, since this node is
-- only used if a formal parameter selector name is present)
-- Explicit_Actual_Parameter (Node3)
-- Next_Named_Actual (Node4-Sem)
---------------------------
-- 6.4 Actual Parameter --
---------------------------
-- EXPLICIT_ACTUAL_PARAMETER ::= EXPRESSION | variable_NAME
---------------------------
-- 6.5 Return Statement --
---------------------------
-- RETURN_STATEMENT ::= return [EXPRESSION];
-- N_Return_Statement
-- Sloc points to RETURN
-- Expression (Node3) (set to Empty if no expression present)
-- Storage_Pool (Node1-Sem)
-- Procedure_To_Call (Node4-Sem)
-- Do_Tag_Check (Flag13-Sem)
-- Return_Type (Node2-Sem)
-- By_Ref (Flag5-Sem)
-- Note: if a range check is required, then Do_Range_Check is set
-- on the Expression. The range check is against Return_Type.
------------------------------
-- 7.1 Package Declaration --
------------------------------
-- PACKAGE_DECLARATION ::= PACKAGE_SPECIFICATION;