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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ C H 5 --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2021, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Aspects; use Aspects;
with Atree; use Atree;
with Checks; use Checks;
with Debug; use Debug;
with Einfo; use Einfo;
with Einfo.Entities; use Einfo.Entities;
with Einfo.Utils; use Einfo.Utils;
with Errout; use Errout;
with Expander; use Expander;
with Exp_Ch6; use Exp_Ch6;
with Exp_Tss; use Exp_Tss;
with Exp_Util; use Exp_Util;
with Freeze; use Freeze;
with Ghost; use Ghost;
with Lib; use Lib;
with Lib.Xref; use Lib.Xref;
with Namet; use Namet;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Sem; use Sem;
with Sem_Aux; use Sem_Aux;
with Sem_Case; use Sem_Case;
with Sem_Ch3; use Sem_Ch3;
with Sem_Ch6; use Sem_Ch6;
with Sem_Ch8; use Sem_Ch8;
with Sem_Dim; use Sem_Dim;
with Sem_Disp; use Sem_Disp;
with Sem_Elab; use Sem_Elab;
with Sem_Eval; use Sem_Eval;
with Sem_Res; use Sem_Res;
with Sem_Type; use Sem_Type;
with Sem_Util; use Sem_Util;
with Sem_Warn; use Sem_Warn;
with Snames; use Snames;
with Stand; use Stand;
with Sinfo; use Sinfo;
with Sinfo.Nodes; use Sinfo.Nodes;
with Sinfo.Utils; use Sinfo.Utils;
with Targparm; use Targparm;
with Tbuild; use Tbuild;
with Ttypes; use Ttypes;
with Uintp; use Uintp;
package body Sem_Ch5 is
Current_Assignment : Node_Id := Empty;
-- This variable holds the node for an assignment that contains target
-- names. The corresponding flag has been set by the parser, and when
-- set the analysis of the RHS must be done with all expansion disabled,
-- because the assignment is reanalyzed after expansion has replaced all
-- occurrences of the target name appropriately.
Unblocked_Exit_Count : Nat := 0;
-- This variable is used when processing if statements, case statements,
-- and block statements. It counts the number of exit points that are not
-- blocked by unconditional transfer instructions: for IF and CASE, these
-- are the branches of the conditional; for a block, they are the statement
-- sequence of the block, and the statement sequences of any exception
-- handlers that are part of the block. When processing is complete, if
-- this count is zero, it means that control cannot fall through the IF,
-- CASE or block statement. This is used for the generation of warning
-- messages. This variable is recursively saved on entry to processing the
-- construct, and restored on exit.
function Has_Sec_Stack_Call (N : Node_Id) return Boolean;
-- N is the node for an arbitrary construct. This function searches the
-- construct N to see if any expressions within it contain function
-- calls that use the secondary stack, returning True if any such call
-- is found, and False otherwise.
procedure Preanalyze_Range (R_Copy : Node_Id);
-- Determine expected type of range or domain of iteration of Ada 2012
-- loop by analyzing separate copy. Do the analysis and resolution of the
-- copy of the bound(s) with expansion disabled, to prevent the generation
-- of finalization actions. This prevents memory leaks when the bounds
-- contain calls to functions returning controlled arrays or when the
-- domain of iteration is a container.
------------------------
-- Analyze_Assignment --
------------------------
-- WARNING: This routine manages Ghost regions. Return statements must be
-- replaced by gotos which jump to the end of the routine and restore the
-- Ghost mode.
procedure Analyze_Assignment (N : Node_Id) is
Lhs : constant Node_Id := Name (N);
Rhs : Node_Id := Expression (N);
procedure Diagnose_Non_Variable_Lhs (N : Node_Id);
-- N is the node for the left hand side of an assignment, and it is not
-- a variable. This routine issues an appropriate diagnostic.
function Is_Protected_Part_Of_Constituent
(Nod : Node_Id) return Boolean;
-- Determine whether arbitrary node Nod denotes a Part_Of constituent of
-- a single protected type.
procedure Kill_Lhs;
-- This is called to kill current value settings of a simple variable
-- on the left hand side. We call it if we find any error in analyzing
-- the assignment, and at the end of processing before setting any new
-- current values in place.
procedure Set_Assignment_Type
(Opnd : Node_Id;
Opnd_Type : in out Entity_Id);
-- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
-- nominal subtype. This procedure is used to deal with cases where the
-- nominal subtype must be replaced by the actual subtype.
procedure Transform_BIP_Assignment (Typ : Entity_Id);
function Should_Transform_BIP_Assignment
(Typ : Entity_Id) return Boolean;
-- If the right-hand side of an assignment statement is a build-in-place
-- call we cannot build in place, so we insert a temp initialized with
-- the call, and transform the assignment statement to copy the temp.
-- Transform_BIP_Assignment does the tranformation, and
-- Should_Transform_BIP_Assignment determines whether we should.
-- The same goes for qualified expressions and conversions whose
-- operand is such a call.
--
-- This is only for nonlimited types; assignment statements are illegal
-- for limited types, but are generated internally for aggregates and
-- init procs. These limited-type are not really assignment statements
-- -- conceptually, they are initializations, so should not be
-- transformed.
--
-- Similarly, for nonlimited types, aggregates and init procs generate
-- assignment statements that are really initializations. These are
-- marked No_Ctrl_Actions.
function Within_Function return Boolean;
-- Determine whether the current scope is a function or appears within
-- one.
-------------------------------
-- Diagnose_Non_Variable_Lhs --
-------------------------------
procedure Diagnose_Non_Variable_Lhs (N : Node_Id) is
begin
-- Not worth posting another error if left hand side already flagged
-- as being illegal in some respect.
if Error_Posted (N) then
return;
-- Some special bad cases of entity names
elsif Is_Entity_Name (N) then
declare
Ent : constant Entity_Id := Entity (N);
begin
if Ekind (Ent) = E_Loop_Parameter
or else Is_Loop_Parameter (Ent)
then
Error_Msg_N ("assignment to loop parameter not allowed", N);
return;
elsif Ekind (Ent) = E_In_Parameter then
Error_Msg_N
("assignment to IN mode parameter not allowed", N);
return;
-- Renamings of protected private components are turned into
-- constants when compiling a protected function. In the case
-- of single protected types, the private component appears
-- directly.
elsif (Is_Prival (Ent) and then Within_Function)
or else Is_Protected_Component (Ent)
then
Error_Msg_N
("protected function cannot modify its protected object",
N);
return;
end if;
end;
-- For indexed components, test prefix if it is in array. We do not
-- want to recurse for cases where the prefix is a pointer, since we
-- may get a message confusing the pointer and what it references.
elsif Nkind (N) = N_Indexed_Component
and then Is_Array_Type (Etype (Prefix (N)))
then
Diagnose_Non_Variable_Lhs (Prefix (N));
return;
-- Another special case for assignment to discriminant
elsif Nkind (N) = N_Selected_Component then
if Present (Entity (Selector_Name (N)))
and then Ekind (Entity (Selector_Name (N))) = E_Discriminant
then
Error_Msg_N ("assignment to discriminant not allowed", N);
return;
-- For selection from record, diagnose prefix, but note that again
-- we only do this for a record, not e.g. for a pointer.
elsif Is_Record_Type (Etype (Prefix (N))) then
Diagnose_Non_Variable_Lhs (Prefix (N));
return;
end if;
end if;
-- If we fall through, we have no special message to issue
Error_Msg_N ("left hand side of assignment must be a variable", N);
end Diagnose_Non_Variable_Lhs;
--------------------------------------
-- Is_Protected_Part_Of_Constituent --
--------------------------------------
function Is_Protected_Part_Of_Constituent
(Nod : Node_Id) return Boolean
is
Encap_Id : Entity_Id;
Var_Id : Entity_Id;
begin
-- Abstract states and variables may act as Part_Of constituents of
-- single protected types, however only variables can be modified by
-- an assignment.
if Is_Entity_Name (Nod) then
Var_Id := Entity (Nod);
if Present (Var_Id) and then Ekind (Var_Id) = E_Variable then
Encap_Id := Encapsulating_State (Var_Id);
-- To qualify, the node must denote a reference to a variable
-- whose encapsulating state is a single protected object.
return
Present (Encap_Id)
and then Is_Single_Protected_Object (Encap_Id);
end if;
end if;
return False;
end Is_Protected_Part_Of_Constituent;
--------------
-- Kill_Lhs --
--------------
procedure Kill_Lhs is
begin
if Is_Entity_Name (Lhs) then
declare
Ent : constant Entity_Id := Entity (Lhs);
begin
if Present (Ent) then
Kill_Current_Values (Ent);
end if;
end;
end if;
end Kill_Lhs;
-------------------------
-- Set_Assignment_Type --
-------------------------
procedure Set_Assignment_Type
(Opnd : Node_Id;
Opnd_Type : in out Entity_Id)
is
Decl : Node_Id;
begin
Require_Entity (Opnd);
-- If the assignment operand is an in-out or out parameter, then we
-- get the actual subtype (needed for the unconstrained case). If the
-- operand is the actual in an entry declaration, then within the
-- accept statement it is replaced with a local renaming, which may
-- also have an actual subtype.
if Is_Entity_Name (Opnd)
and then (Ekind (Entity (Opnd)) in E_Out_Parameter
| E_In_Out_Parameter
| E_Generic_In_Out_Parameter
or else
(Ekind (Entity (Opnd)) = E_Variable
and then Nkind (Parent (Entity (Opnd))) =
N_Object_Renaming_Declaration
and then Nkind (Parent (Parent (Entity (Opnd)))) =
N_Accept_Statement))
then
Opnd_Type := Get_Actual_Subtype (Opnd);
-- If assignment operand is a component reference, then we get the
-- actual subtype of the component for the unconstrained case.
elsif Nkind (Opnd) in N_Selected_Component | N_Explicit_Dereference
and then not Is_Unchecked_Union (Opnd_Type)
then
Decl := Build_Actual_Subtype_Of_Component (Opnd_Type, Opnd);
if Present (Decl) then
Insert_Action (N, Decl);
Mark_Rewrite_Insertion (Decl);
Analyze (Decl);
Opnd_Type := Defining_Identifier (Decl);
Set_Etype (Opnd, Opnd_Type);
Freeze_Itype (Opnd_Type, N);
elsif Is_Constrained (Etype (Opnd)) then
Opnd_Type := Etype (Opnd);
end if;
-- For slice, use the constrained subtype created for the slice
elsif Nkind (Opnd) = N_Slice then
Opnd_Type := Etype (Opnd);
end if;
end Set_Assignment_Type;
-------------------------------------
-- Should_Transform_BIP_Assignment --
-------------------------------------
function Should_Transform_BIP_Assignment
(Typ : Entity_Id) return Boolean
is
begin
if Expander_Active
and then not Is_Limited_View (Typ)
and then Is_Build_In_Place_Result_Type (Typ)
and then not No_Ctrl_Actions (N)
then
-- This function is called early, before name resolution is
-- complete, so we have to deal with things that might turn into
-- function calls later. N_Function_Call and N_Op nodes are the
-- obvious case. An N_Identifier or N_Expanded_Name is a
-- parameterless function call if it denotes a function.
-- Finally, an attribute reference can be a function call.
declare
Unqual_Rhs : constant Node_Id := Unqual_Conv (Rhs);
begin
case Nkind (Unqual_Rhs) is
when N_Function_Call
| N_Op
=>
return True;
when N_Expanded_Name
| N_Identifier
=>
return
Ekind (Entity (Unqual_Rhs)) in E_Function | E_Operator;
-- T'Input will turn into a call whose result type is T
when N_Attribute_Reference =>
return Attribute_Name (Unqual_Rhs) = Name_Input;
when others =>
return False;
end case;
end;
else
return False;
end if;
end Should_Transform_BIP_Assignment;
------------------------------
-- Transform_BIP_Assignment --
------------------------------
procedure Transform_BIP_Assignment (Typ : Entity_Id) is
-- Tranform "X : [constant] T := F (...);" into:
--
-- Temp : constant T := F (...);
-- X := Temp;
Loc : constant Source_Ptr := Sloc (N);
Def_Id : constant Entity_Id := Make_Temporary (Loc, 'Y', Rhs);
Obj_Decl : constant Node_Id :=
Make_Object_Declaration (Loc,
Defining_Identifier => Def_Id,
Constant_Present => True,
Object_Definition => New_Occurrence_Of (Typ, Loc),
Expression => Rhs,
Has_Init_Expression => True);
begin
Set_Etype (Def_Id, Typ);
Set_Expression (N, New_Occurrence_Of (Def_Id, Loc));
-- At this point, Rhs is no longer equal to Expression (N), so:
Rhs := Expression (N);
Insert_Action (N, Obj_Decl);
end Transform_BIP_Assignment;
---------------------
-- Within_Function --
---------------------
function Within_Function return Boolean is
Scop_Id : constant Entity_Id := Current_Scope;
begin
if Ekind (Scop_Id) = E_Function then
return True;
elsif Ekind (Enclosing_Dynamic_Scope (Scop_Id)) = E_Function then
return True;
end if;
return False;
end Within_Function;
-- Local variables
Saved_GM : constant Ghost_Mode_Type := Ghost_Mode;
Saved_IGR : constant Node_Id := Ignored_Ghost_Region;
-- Save the Ghost-related attributes to restore on exit
T1 : Entity_Id;
T2 : Entity_Id;
Save_Full_Analysis : Boolean := False;
-- Force initialization to facilitate static analysis
-- Start of processing for Analyze_Assignment
begin
Mark_Coextensions (N, Rhs);
-- Preserve relevant elaboration-related attributes of the context which
-- are no longer available or very expensive to recompute once analysis,
-- resolution, and expansion are over.
Mark_Elaboration_Attributes
(N_Id => N,
Checks => True,
Modes => True);
-- An assignment statement is Ghost when the left hand side denotes a
-- Ghost entity. Set the mode now to ensure that any nodes generated
-- during analysis and expansion are properly marked as Ghost.
Mark_And_Set_Ghost_Assignment (N);
if Has_Target_Names (N) then
pragma Assert (No (Current_Assignment));
Current_Assignment := N;
Expander_Mode_Save_And_Set (False);
Save_Full_Analysis := Full_Analysis;
Full_Analysis := False;
end if;
Analyze (Lhs);
Analyze (Rhs);
-- Ensure that we never do an assignment on a variable marked as
-- Is_Safe_To_Reevaluate.
pragma Assert
(not Is_Entity_Name (Lhs)
or else Ekind (Entity (Lhs)) /= E_Variable
or else not Is_Safe_To_Reevaluate (Entity (Lhs)));
-- Start type analysis for assignment
T1 := Etype (Lhs);
-- In the most general case, both Lhs and Rhs can be overloaded, and we
-- must compute the intersection of the possible types on each side.
if Is_Overloaded (Lhs) then
declare
I : Interp_Index;
It : Interp;
begin
T1 := Any_Type;
Get_First_Interp (Lhs, I, It);
while Present (It.Typ) loop
-- An indexed component with generalized indexing is always
-- overloaded with the corresponding dereference. Discard the
-- interpretation that yields a reference type, which is not
-- assignable.
if Nkind (Lhs) = N_Indexed_Component
and then Present (Generalized_Indexing (Lhs))
and then Has_Implicit_Dereference (It.Typ)
then
null;
-- This may be a call to a parameterless function through an
-- implicit dereference, so discard interpretation as well.
elsif Is_Entity_Name (Lhs)
and then Has_Implicit_Dereference (It.Typ)
then
null;
elsif Has_Compatible_Type (Rhs, It.Typ) then
if T1 = Any_Type then
T1 := It.Typ;
else
-- An explicit dereference is overloaded if the prefix
-- is. Try to remove the ambiguity on the prefix, the
-- error will be posted there if the ambiguity is real.
if Nkind (Lhs) = N_Explicit_Dereference then
declare
PI : Interp_Index;
PI1 : Interp_Index := 0;
PIt : Interp;
Found : Boolean;
begin
Found := False;
Get_First_Interp (Prefix (Lhs), PI, PIt);
while Present (PIt.Typ) loop
if Is_Access_Type (PIt.Typ)
and then Has_Compatible_Type
(Rhs, Designated_Type (PIt.Typ))
then
if Found then
PIt :=
Disambiguate (Prefix (Lhs),
PI1, PI, Any_Type);
if PIt = No_Interp then
Error_Msg_N
("ambiguous left-hand side in "
& "assignment", Lhs);
exit;
else
Resolve (Prefix (Lhs), PIt.Typ);
end if;
exit;
else
Found := True;
PI1 := PI;
end if;
end if;
Get_Next_Interp (PI, PIt);
end loop;
end;
else
Error_Msg_N
("ambiguous left-hand side in assignment", Lhs);
exit;
end if;
end if;
end if;
Get_Next_Interp (I, It);
end loop;
end;
if T1 = Any_Type then
Error_Msg_N
("no valid types for left-hand side for assignment", Lhs);
Kill_Lhs;
goto Leave;
end if;
end if;
-- Deal with build-in-place calls for nonlimited types. We don't do this
-- later, because resolving the rhs tranforms it incorrectly for build-
-- in-place.
if Should_Transform_BIP_Assignment (Typ => T1) then
-- In certain cases involving user-defined concatenation operators,
-- we need to resolve the right-hand side before transforming the
-- assignment.
case Nkind (Unqual_Conv (Rhs)) is
when N_Function_Call =>
declare
Actual : Node_Id :=
First (Parameter_Associations (Unqual_Conv (Rhs)));
Actual_Exp : Node_Id;
begin
while Present (Actual) loop
if Nkind (Actual) = N_Parameter_Association then
Actual_Exp := Explicit_Actual_Parameter (Actual);
else
Actual_Exp := Actual;
end if;
if Nkind (Actual_Exp) = N_Op_Concat then
Resolve (Rhs, T1);
exit;
end if;
Next (Actual);
end loop;
end;
when N_Attribute_Reference
| N_Expanded_Name
| N_Identifier
| N_Op
=>
null;
when others =>
raise Program_Error;
end case;
Transform_BIP_Assignment (Typ => T1);
end if;
pragma Assert (not Should_Transform_BIP_Assignment (Typ => T1));
-- The resulting assignment type is T1, so now we will resolve the left
-- hand side of the assignment using this determined type.
Resolve (Lhs, T1);
-- Cases where Lhs is not a variable. In an instance or an inlined body
-- no need for further check because assignment was legal in template.
if In_Inlined_Body then
null;
elsif not Is_Variable (Lhs) then
-- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
-- protected object.
declare
Ent : Entity_Id;
S : Entity_Id;
begin
if Ada_Version >= Ada_2005 then
-- Handle chains of renamings
Ent := Lhs;
while Nkind (Ent) in N_Has_Entity
and then Present (Entity (Ent))
and then Present (Renamed_Object (Entity (Ent)))
loop
Ent := Renamed_Object (Entity (Ent));
end loop;
if (Nkind (Ent) = N_Attribute_Reference
and then Attribute_Name (Ent) = Name_Priority)
-- Renamings of the attribute Priority applied to protected
-- objects have been previously expanded into calls to the
-- Get_Ceiling run-time subprogram.
or else Is_Expanded_Priority_Attribute (Ent)
then
-- The enclosing subprogram cannot be a protected function
S := Current_Scope;
while not (Is_Subprogram (S)
and then Convention (S) = Convention_Protected)
and then S /= Standard_Standard
loop
S := Scope (S);
end loop;
if Ekind (S) = E_Function
and then Convention (S) = Convention_Protected
then
Error_Msg_N
("protected function cannot modify its protected " &
"object",
Lhs);
end if;
-- Changes of the ceiling priority of the protected object
-- are only effective if the Ceiling_Locking policy is in
-- effect (AARM D.5.2 (5/2)).
if Locking_Policy /= 'C' then
Error_Msg_N
("assignment to the attribute PRIORITY has no effect??",
Lhs);
Error_Msg_N
("\since no Locking_Policy has been specified??", Lhs);
end if;
goto Leave;
end if;
end if;
end;
Diagnose_Non_Variable_Lhs (Lhs);
goto Leave;
-- Error of assigning to limited type. We do however allow this in
-- certain cases where the front end generates the assignments.
elsif Is_Limited_Type (T1)
and then not Assignment_OK (Lhs)
and then not Assignment_OK (Original_Node (Lhs))
then
-- CPP constructors can only be called in declarations
if Is_CPP_Constructor_Call (Rhs) then
Error_Msg_N ("invalid use of 'C'P'P constructor", Rhs);
else
Error_Msg_N
("left hand of assignment must not be limited type", Lhs);
Explain_Limited_Type (T1, Lhs);
end if;
goto Leave;
-- A class-wide type may be a limited view. This illegal case is not
-- caught by previous checks.
elsif Ekind (T1) = E_Class_Wide_Type and then From_Limited_With (T1) then
Error_Msg_NE ("invalid use of limited view of&", Lhs, T1);
goto Leave;
-- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
-- abstract. This is only checked when the assignment Comes_From_Source,
-- because in some cases the expander generates such assignments (such
-- in the _assign operation for an abstract type).
elsif Is_Abstract_Type (T1) and then Comes_From_Source (N) then
Error_Msg_N
("target of assignment operation must not be abstract", Lhs);
end if;
-- Variables which are Part_Of constituents of single protected types
-- behave in similar fashion to protected components. Such variables
-- cannot be modified by protected functions.
if Is_Protected_Part_Of_Constituent (Lhs) and then Within_Function then
Error_Msg_N
("protected function cannot modify its protected object", Lhs);
end if;
-- Resolution may have updated the subtype, in case the left-hand side
-- is a private protected component. Use the correct subtype to avoid
-- scoping issues in the back-end.
T1 := Etype (Lhs);
-- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
-- type. For example:
-- limited with P;
-- package Pkg is
-- type Acc is access P.T;
-- end Pkg;
-- with Pkg; use Acc;
-- procedure Example is
-- A, B : Acc;
-- begin
-- A.all := B.all; -- ERROR
-- end Example;
if Nkind (Lhs) = N_Explicit_Dereference
and then Ekind (T1) = E_Incomplete_Type
then
Error_Msg_N ("invalid use of incomplete type", Lhs);
Kill_Lhs;
goto Leave;
end if;
-- Now we can complete the resolution of the right hand side
Set_Assignment_Type (Lhs, T1);
-- If the target of the assignment is an entity of a mutable type and
-- the expression is a conditional expression, its alternatives can be
-- of different subtypes of the nominal type of the LHS, so they must be
-- resolved with the base type, given that their subtype may differ from
-- that of the target mutable object.
if Is_Entity_Name (Lhs)
and then Is_Assignable (Entity (Lhs))
and then Is_Composite_Type (T1)
and then not Is_Constrained (Etype (Entity (Lhs)))
and then Nkind (Rhs) in N_If_Expression | N_Case_Expression
then
Resolve (Rhs, Base_Type (T1));
else
Resolve (Rhs, T1);
end if;
-- This is the point at which we check for an unset reference
Check_Unset_Reference (Rhs);
Check_Unprotected_Access (Lhs, Rhs);
-- Remaining steps are skipped if Rhs was syntactically in error
if Rhs = Error then
Kill_Lhs;
goto Leave;
end if;
T2 := Etype (Rhs);
if not Covers (T1, T2) then
Wrong_Type (Rhs, Etype (Lhs));
Kill_Lhs;
goto Leave;
end if;
-- Ada 2005 (AI-326): In case of explicit dereference of incomplete
-- types, use the non-limited view if available
if Nkind (Rhs) = N_Explicit_Dereference
and then Is_Tagged_Type (T2)
and then Has_Non_Limited_View (T2)
then
T2 := Non_Limited_View (T2);
end if;
Set_Assignment_Type (Rhs, T2);
if Total_Errors_Detected /= 0 then
if No (T1) then
T1 := Any_Type;
end if;
if No (T2) then
T2 := Any_Type;
end if;
end if;
if T1 = Any_Type or else T2 = Any_Type then
Kill_Lhs;
goto Leave;
end if;
-- If the rhs is class-wide or dynamically tagged, then require the lhs
-- to be class-wide. The case where the rhs is a dynamically tagged call
-- to a dispatching operation with a controlling access result is
-- excluded from this check, since the target has an access type (and
-- no tag propagation occurs in that case).
if (Is_Class_Wide_Type (T2)
or else (Is_Dynamically_Tagged (Rhs)
and then not Is_Access_Type (T1)))
and then not Is_Class_Wide_Type (T1)
then
Error_Msg_N ("dynamically tagged expression not allowed!", Rhs);
elsif Is_Class_Wide_Type (T1)
and then not Is_Class_Wide_Type (T2)
and then not Is_Tag_Indeterminate (Rhs)
and then not Is_Dynamically_Tagged (Rhs)
then
Error_Msg_N ("dynamically tagged expression required!", Rhs);
end if;
-- Propagate the tag from a class-wide target to the rhs when the rhs
-- is a tag-indeterminate call.
if Is_Tag_Indeterminate (Rhs) then
if Is_Class_Wide_Type (T1) then
Propagate_Tag (Lhs, Rhs);
elsif Nkind (Rhs) = N_Function_Call
and then Is_Entity_Name (Name (Rhs))
and then Is_Abstract_Subprogram (Entity (Name (Rhs)))
then
Error_Msg_N
("call to abstract function must be dispatching", Name (Rhs));
elsif Nkind (Rhs) = N_Qualified_Expression
and then Nkind (Expression (Rhs)) = N_Function_Call
and then Is_Entity_Name (Name (Expression (Rhs)))
and then
Is_Abstract_Subprogram (Entity (Name (Expression (Rhs))))
then
Error_Msg_N
("call to abstract function must be dispatching",
Name (Expression (Rhs)));
end if;
end if;
-- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
-- apply an implicit conversion of the rhs to that type to force
-- appropriate static and run-time accessibility checks. This applies
-- as well to anonymous access-to-subprogram types that are component
-- subtypes or formal parameters.
if Ada_Version >= Ada_2005 and then Is_Access_Type (T1) then
if Is_Local_Anonymous_Access (T1)
or else Ekind (T2) = E_Anonymous_Access_Subprogram_Type
-- Handle assignment to an Ada 2012 stand-alone object
-- of an anonymous access type.
or else (Ekind (T1) = E_Anonymous_Access_Type
and then Nkind (Associated_Node_For_Itype (T1)) =
N_Object_Declaration)
then
Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
Analyze_And_Resolve (Rhs, T1);
end if;
end if;
-- Ada 2005 (AI-231): Assignment to not null variable
if Ada_Version >= Ada_2005
and then Can_Never_Be_Null (T1)
and then not Assignment_OK (Lhs)
then
-- Case where we know the right hand side is null
if Known_Null (Rhs) then
Apply_Compile_Time_Constraint_Error
(N => Rhs,
Msg =>
"(Ada 2005) NULL not allowed in null-excluding objects??",
Reason => CE_Null_Not_Allowed);
-- We still mark this as a possible modification, that's necessary
-- to reset Is_True_Constant, and desirable for xref purposes.
Note_Possible_Modification (Lhs, Sure => True);
goto Leave;
-- If we know the right hand side is non-null, then we convert to the
-- target type, since we don't need a run time check in that case.
elsif not Can_Never_Be_Null (T2) then
Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
Analyze_And_Resolve (Rhs, T1);
end if;
end if;
if Is_Scalar_Type (T1) then
declare
function Omit_Range_Check_For_Streaming return Boolean;
-- Return True if this assignment statement is the expansion of
-- a Some_Scalar_Type'Read procedure call such that all conditions
-- of 13.3.2(35)'s "no check is made" rule are met.
------------------------------------
-- Omit_Range_Check_For_Streaming --
------------------------------------
function Omit_Range_Check_For_Streaming return Boolean is
begin
-- Have we got an implicitly generated assignment to a
-- component of a composite object? If not, return False.
if Comes_From_Source (N)
or else Serious_Errors_Detected > 0
or else Nkind (Lhs)
not in N_Selected_Component | N_Indexed_Component
then
return False;
end if;
declare
Pref : constant Node_Id := Prefix (Lhs);
begin
-- Are we in the implicitly-defined Read subprogram
-- for a composite type, reading the value of a scalar
-- component from the stream? If not, return False.
if Nkind (Pref) /= N_Identifier
or else not Is_TSS (Scope (Entity (Pref)), TSS_Stream_Read)
then
return False;
end if;
-- Return False if Default_Value or Default_Component_Value
-- aspect applies.
if Has_Default_Aspect (Etype (Lhs))
or else Has_Default_Aspect (Etype (Pref))
then
return False;
-- Are we assigning to a record component (as opposed to
-- an array component)?
elsif Nkind (Lhs) = N_Selected_Component then
-- Are we assigning to a nondiscriminant component
-- that lacks a default initial value expression?
-- If so, return True.
declare
Comp_Id : constant Entity_Id :=
Original_Record_Component
(Entity (Selector_Name (Lhs)));
begin
if Ekind (Comp_Id) = E_Component
and then Nkind (Parent (Comp_Id))
= N_Component_Declaration
and then
not Present (Expression (Parent (Comp_Id)))
then
return True;
end if;
return False;
end;
-- We are assigning to a component of an array
-- (and we tested for both Default_Value and
-- Default_Component_Value above), so return True.
else
pragma Assert (Nkind (Lhs) = N_Indexed_Component);
return True;
end if;
end;
end Omit_Range_Check_For_Streaming;
begin
if not Omit_Range_Check_For_Streaming then
Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
end if;
end;
-- For array types, verify that lengths match. If the right hand side
-- is a function call that has been inlined, the assignment has been
-- rewritten as a block, and the constraint check will be applied to the
-- assignment within the block.
elsif Is_Array_Type (T1)
and then (Nkind (Rhs) /= N_Type_Conversion
or else Is_Constrained (Etype (Rhs)))
and then (Nkind (Rhs) /= N_Function_Call
or else Nkind (N) /= N_Block_Statement)
then
-- Assignment verifies that the length of the Lhs and Rhs are equal,
-- but of course the indexes do not have to match. If the right-hand
-- side is a type conversion to an unconstrained type, a length check
-- is performed on the expression itself during expansion. In rare
-- cases, the redundant length check is computed on an index type
-- with a different representation, triggering incorrect code in the
-- back end.
Apply_Length_Check_On_Assignment (Rhs, Etype (Lhs), Lhs);
else
-- Discriminant checks are applied in the course of expansion
null;
end if;
-- Note: modifications of the Lhs may only be recorded after
-- checks have been applied.
Note_Possible_Modification (Lhs, Sure => True);
-- ??? a real accessibility check is needed when ???
-- Post warning for redundant assignment or variable to itself
if Warn_On_Redundant_Constructs
-- We only warn for source constructs
and then Comes_From_Source (N)
-- Where the object is the same on both sides
and then Same_Object (Lhs, Original_Node (Rhs))
-- But exclude the case where the right side was an operation that
-- got rewritten (e.g. JUNK + K, where K was known to be zero). We
-- don't want to warn in such a case, since it is reasonable to write
-- such expressions especially when K is defined symbolically in some
-- other package.
and then Nkind (Original_Node (Rhs)) not in N_Op
then
if Nkind (Lhs) in N_Has_Entity then
Error_Msg_NE -- CODEFIX
("?r?useless assignment of & to itself!", N, Entity (Lhs));
else
Error_Msg_N -- CODEFIX
("?r?useless assignment of object to itself!", N);
end if;
end if;
-- Check for non-allowed composite assignment
if not Support_Composite_Assign_On_Target
and then (Is_Array_Type (T1) or else Is_Record_Type (T1))
and then (not Has_Size_Clause (T1)
or else Esize (T1) > Ttypes.System_Max_Integer_Size)
then
Error_Msg_CRT ("composite assignment", N);
end if;
-- Check elaboration warning for left side if not in elab code
if Legacy_Elaboration_Checks
and not In_Subprogram_Or_Concurrent_Unit
then
Check_Elab_Assign (Lhs);
end if;
-- Save the scenario for later examination by the ABE Processing phase
Record_Elaboration_Scenario (N);
-- Set Referenced_As_LHS if appropriate. We only set this flag if the
-- assignment is a source assignment in the extended main source unit.
-- We are not interested in any reference information outside this
-- context, or in compiler generated assignment statements.
if Comes_From_Source (N)
and then In_Extended_Main_Source_Unit (Lhs)
then
Set_Referenced_Modified (Lhs, Out_Param => False);
end if;
-- RM 7.3.2 (12/3): An assignment to a view conversion (from a type to
-- one of its ancestors) requires an invariant check. Apply check only
-- if expression comes from source, otherwise it will be applied when
-- value is assigned to source entity. This is not done in GNATprove
-- mode, as GNATprove handles invariant checks itself.
if Nkind (Lhs) = N_Type_Conversion
and then Has_Invariants (Etype (Expression (Lhs)))
and then Comes_From_Source (Expression (Lhs))
and then not GNATprove_Mode
then
Insert_After (N, Make_Invariant_Call (Expression (Lhs)));
end if;
-- Final step. If left side is an entity, then we may be able to reset
-- the current tracked values to new safe values. We only have something
-- to do if the left side is an entity name, and expansion has not
-- modified the node into something other than an assignment, and of
-- course we only capture values if it is safe to do so.
if Is_Entity_Name (Lhs)
and then Nkind (N) = N_Assignment_Statement
then
declare
Ent : constant Entity_Id := Entity (Lhs);
begin
if Safe_To_Capture_Value (N, Ent) then
-- If simple variable on left side, warn if this assignment
-- blots out another one (rendering it useless). We only do
-- this for source assignments, otherwise we can generate bogus
-- warnings when an assignment is rewritten as another
-- assignment, and gets tied up with itself.
-- We also omit the warning if the RHS includes target names,
-- that is to say the Ada 2022 "@" that denotes an instance of
-- the LHS, which indicates that the current value is being
-- used. Note that this implicit reference to the entity on
-- the RHS is not treated as a source reference.
-- There may have been a previous reference to a component of
-- the variable, which in general removes the Last_Assignment
-- field of the variable to indicate a relevant use of the
-- previous assignment. However, if the assignment is to a
-- subcomponent the reference may not have registered, because
-- it is not possible to determine whether the context is an
-- assignment. In those cases we generate a Deferred_Reference,
-- to be used at the end of compilation to generate the right
-- kind of reference, and we suppress a potential warning for
-- a useless assignment, which might be premature. This may
-- lose a warning in rare cases, but seems preferable to a
-- misleading warning.
if Warn_On_Modified_Unread
and then Is_Assignable (Ent)
and then Comes_From_Source (N)
and then In_Extended_Main_Source_Unit (Ent)
and then not Has_Deferred_Reference (Ent)
and then not Has_Target_Names (N)
then
Warn_On_Useless_Assignment (Ent, N);
end if;
-- If we are assigning an access type and the left side is an
-- entity, then make sure that the Is_Known_[Non_]Null flags
-- properly reflect the state of the entity after assignment.
if Is_Access_Type (T1) then
if Known_Non_Null (Rhs) then
Set_Is_Known_Non_Null (Ent, True);
elsif Known_Null (Rhs)
and then not Can_Never_Be_Null (Ent)
then
Set_Is_Known_Null (Ent, True);
else
Set_Is_Known_Null (Ent, False);
if not Can_Never_Be_Null (Ent) then
Set_Is_Known_Non_Null (Ent, False);
end if;
end if;
-- For discrete types, we may be able to set the current value
-- if the value is known at compile time.
elsif Is_Discrete_Type (T1)
and then Compile_Time_Known_Value (Rhs)
then
Set_Current_Value (Ent, Rhs);
else
Set_Current_Value (Ent, Empty);
end if;
-- If not safe to capture values, kill them
else
Kill_Lhs;
end if;
end;
end if;
-- If assigning to an object in whole or in part, note location of
-- assignment in case no one references value. We only do this for
-- source assignments, otherwise we can generate bogus warnings when an
-- assignment is rewritten as another assignment, and gets tied up with
-- itself.
declare
Ent : constant Entity_Id := Get_Enclosing_Object (Lhs);
begin
if Present (Ent)
and then Safe_To_Capture_Value (N, Ent)
and then Nkind (N) = N_Assignment_Statement
and then Warn_On_Modified_Unread
and then Is_Assignable (Ent)
and then Comes_From_Source (N)
and then In_Extended_Main_Source_Unit (Ent)
then
Set_Last_Assignment (Ent, Lhs);
end if;
end;
Analyze_Dimension (N);
<<Leave>>
Restore_Ghost_Region (Saved_GM, Saved_IGR);
-- If the right-hand side contains target names, expansion has been
-- disabled to prevent expansion that might move target names out of
-- the context of the assignment statement. Restore the expander mode
-- now so that assignment statement can be properly expanded.
if Nkind (N) = N_Assignment_Statement then
if Has_Target_Names (N) then
Expander_Mode_Restore;
Full_Analysis := Save_Full_Analysis;
Current_Assignment := Empty;
end if;
pragma Assert (not Should_Transform_BIP_Assignment (Typ => T1));
end if;
end Analyze_Assignment;
-----------------------------
-- Analyze_Block_Statement --
-----------------------------
procedure Analyze_Block_Statement (N : Node_Id) is
procedure Install_Return_Entities (Scop : Entity_Id);
-- Install all entities of return statement scope Scop in the visibility
-- chain except for the return object since its entity is reused in a
-- renaming.
-----------------------------
-- Install_Return_Entities --
-----------------------------
procedure Install_Return_Entities (Scop : Entity_Id) is
Id : Entity_Id;
begin
Id := First_Entity (Scop);
while Present (Id) loop
-- Do not install the return object
if Ekind (Id) not in E_Constant | E_Variable
or else not Is_Return_Object (Id)
then
Install_Entity (Id);
end if;
Next_Entity (Id);
end loop;
end Install_Return_Entities;
-- Local constants and variables
Decls : constant List_Id := Declarations (N);
Id : constant Node_Id := Identifier (N);
HSS : constant Node_Id := Handled_Statement_Sequence (N);
Is_BIP_Return_Statement : Boolean;
-- Start of processing for Analyze_Block_Statement
begin
-- If no handled statement sequence is present, things are really messed
-- up, and we just return immediately (defence against previous errors).
if No (HSS) then
Check_Error_Detected;
return;
end if;
-- Detect whether the block is actually a rewritten return statement of
-- a build-in-place function.
Is_BIP_Return_Statement :=
Present (Id)
and then Present (Entity (Id))
and then Ekind (Entity (Id)) = E_Return_Statement
and then Is_Build_In_Place_Function
(Return_Applies_To (Entity (Id)));
-- Normal processing with HSS present
declare
EH : constant List_Id := Exception_Handlers (HSS);
Ent : Entity_Id := Empty;
S : Entity_Id;
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
-- Recursively save value of this global, will be restored on exit
begin
-- Initialize unblocked exit count for statements of begin block
-- plus one for each exception handler that is present.
Unblocked_Exit_Count := 1;
if Present (EH) then
Unblocked_Exit_Count := Unblocked_Exit_Count + List_Length (EH);
end if;
-- If a label is present analyze it and mark it as referenced
if Present (Id) then
Analyze (Id);
Ent := Entity (Id);
-- An error defense. If we have an identifier, but no entity, then
-- something is wrong. If previous errors, then just remove the
-- identifier and continue, otherwise raise an exception.
if No (Ent) then
Check_Error_Detected;
Set_Identifier (N, Empty);
else
if Ekind (Ent) = E_Label then
Reinit_Field_To_Zero (Ent, F_Enclosing_Scope);
end if;
Mutate_Ekind (Ent, E_Block);
Generate_Reference (Ent, N, ' ');
Generate_Definition (Ent);
if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
Set_Label_Construct (Parent (Ent), N);
end if;
end if;
end if;
-- If no entity set, create a label entity
if No (Ent) then
Ent := New_Internal_Entity (E_Block, Current_Scope, Sloc (N), 'B');
Set_Identifier (N, New_Occurrence_Of (Ent, Sloc (N)));
Set_Parent (Ent, N);
end if;
Set_Etype (Ent, Standard_Void_Type);
Set_Block_Node (Ent, Identifier (N));
Push_Scope (Ent);
-- The block served as an extended return statement. Ensure that any
-- entities created during the analysis and expansion of the return
-- object declaration are once again visible.
if Is_BIP_Return_Statement then
Install_Return_Entities (Ent);
end if;
if Present (Decls) then
Analyze_Declarations (Decls);
Check_Completion;
Inspect_Deferred_Constant_Completion (Decls);
end if;
Analyze (HSS);
Process_End_Label (HSS, 'e', Ent);
-- If exception handlers are present, then we indicate that enclosing
-- scopes contain a block with handlers. We only need to mark non-
-- generic scopes.
if Present (EH) then
S := Scope (Ent);
loop
Set_Has_Nested_Block_With_Handler (S);
exit when Is_Overloadable (S)
or else Ekind (S) = E_Package
or else Is_Generic_Unit (S);
S := Scope (S);
end loop;
end if;
Check_References (Ent);
Update_Use_Clause_Chain;
End_Scope;
if Unblocked_Exit_Count = 0 then
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
Check_Unreachable_Code (N);
else
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
end if;
end;
end Analyze_Block_Statement;
--------------------------------
-- Analyze_Compound_Statement --
--------------------------------
procedure Analyze_Compound_Statement (N : Node_Id) is
begin
Analyze_List (Actions (N));
end Analyze_Compound_Statement;
----------------------------
-- Analyze_Case_Statement --
----------------------------
procedure Analyze_Case_Statement (N : Node_Id) is
Exp : constant Node_Id := Expression (N);
Statements_Analyzed : Boolean := False;
-- Set True if at least some statement sequences get analyzed. If False
-- on exit, means we had a serious error that prevented full analysis of
-- the case statement, and as a result it is not a good idea to output
-- warning messages about unreachable code.
Is_General_Case_Statement : Boolean := False;
-- Set True (later) if type of case expression is not discrete
procedure Non_Static_Choice_Error (Choice : Node_Id);
-- Error routine invoked by the generic instantiation below when the
-- case statement has a non static choice.
procedure Process_Statements (Alternative : Node_Id);
-- Analyzes the statements associated with a case alternative. Needed
-- by instantiation below.
package Analyze_Case_Choices is new
Generic_Analyze_Choices
(Process_Associated_Node => Process_Statements);
use Analyze_Case_Choices;
-- Instantiation of the generic choice analysis package
package Check_Case_Choices is new
Generic_Check_Choices
(Process_Empty_Choice => No_OP,
Process_Non_Static_Choice => Non_Static_Choice_Error,
Process_Associated_Node => No_OP);
use Check_Case_Choices;
-- Instantiation of the generic choice processing package
-----------------------------
-- Non_Static_Choice_Error --
-----------------------------
procedure Non_Static_Choice_Error (Choice : Node_Id) is
begin
Flag_Non_Static_Expr
("choice given in case statement is not static!", Choice);
end Non_Static_Choice_Error;
------------------------
-- Process_Statements --
------------------------
procedure Process_Statements (Alternative : Node_Id) is
Choices : constant List_Id := Discrete_Choices (Alternative);
Ent : Entity_Id;
begin
if Is_General_Case_Statement then
return;
-- Processing deferred in this case; decls associated with
-- pattern match bindings don't exist yet.
end if;
Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
Statements_Analyzed := True;
-- An interesting optimization. If the case statement expression
-- is a simple entity, then we can set the current value within an
-- alternative if the alternative has one possible value.
-- case N is
-- when 1 => alpha
-- when 2 | 3 => beta
-- when others => gamma
-- Here we know that N is initially 1 within alpha, but for beta and
-- gamma, we do not know anything more about the initial value.
if Is_Entity_Name (Exp) then
Ent := Entity (Exp);
if Is_Object (Ent) then
if List_Length (Choices) = 1
and then Nkind (First (Choices)) in N_Subexpr
and then Compile_Time_Known_Value (First (Choices))
then
Set_Current_Value (Entity (Exp), First (Choices));
end if;
Analyze_Statements (Statements (Alternative));
-- After analyzing the case, set the current value to empty
-- since we won't know what it is for the next alternative
-- (unless reset by this same circuit), or after the case.
Set_Current_Value (Entity (Exp), Empty);
return;
end if;
end if;
-- Case where expression is not an entity name of an object
Analyze_Statements (Statements (Alternative));
end Process_Statements;
-- Local variables
Exp_Type : Entity_Id;
Exp_Btype : Entity_Id;
Others_Present : Boolean;
-- Indicates if Others was present
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
-- Recursively save value of this global, will be restored on exit
-- Start of processing for Analyze_Case_Statement
begin
Analyze (Exp);
-- The expression must be of any discrete type. In rare cases, the
-- expander constructs a case statement whose expression has a private
-- type whose full view is discrete. This can happen when generating
-- a stream operation for a variant type after the type is frozen,
-- when the partial of view of the type of the discriminant is private.
-- In that case, use the full view to analyze case alternatives.
if not Is_Overloaded (Exp)
and then not Comes_From_Source (N)
and then Is_Private_Type (Etype (Exp))
and then Present (Full_View (Etype (Exp)))
and then Is_Discrete_Type (Full_View (Etype (Exp)))
then
Resolve (Exp);
Exp_Type := Full_View (Etype (Exp));
-- For Ada, overloading might be ok because subsequently filtering
-- out non-discretes may resolve the ambiguity.
-- But GNAT extensions allow casing on non-discretes.
elsif Extensions_Allowed and then Is_Overloaded (Exp) then
-- It would be nice if we could generate all the right error
-- messages by calling "Resolve (Exp, Any_Type);" in the
-- same way that they are generated a few lines below by the
-- call "Analyze_And_Resolve (Exp, Any_Discrete);".
-- Unfortunately, Any_Type and Any_Discrete are not treated
-- consistently (specifically, by Sem_Type.Covers), so that
-- doesn't work.
Error_Msg_N
("selecting expression of general case statement is ambiguous",
Exp);
return;
-- Check for a GNAT-extension "general" case statement (i.e., one where
-- the type of the selecting expression is not discrete).
elsif Extensions_Allowed
and then not Is_Discrete_Type (Etype (Exp))
then
Resolve (Exp, Etype (Exp));
Exp_Type := Etype (Exp);
Is_General_Case_Statement := True;
else
Analyze_And_Resolve (Exp, Any_Discrete);
Exp_Type := Etype (Exp);
end if;
Check_Unset_Reference (Exp);
Exp_Btype := Base_Type (Exp_Type);
-- The expression must be of a discrete type which must be determinable
-- independently of the context in which the expression occurs, but
-- using the fact that the expression must be of a discrete type.
-- Moreover, the type this expression must not be a character literal
-- (which is always ambiguous) or, for Ada-83, a generic formal type.
-- If error already reported by Resolve, nothing more to do
if Exp_Btype = Any_Discrete or else Exp_Btype = Any_Type then
return;
elsif Exp_Btype = Any_Character then
Error_Msg_N
("character literal as case expression is ambiguous", Exp);
return;
elsif Ada_Version = Ada_83
and then (Is_Generic_Type (Exp_Btype)
or else Is_Generic_Type (Root_Type (Exp_Btype)))
then
Error_Msg_N
("(Ada 83) case expression cannot be of a generic type", Exp);
return;
elsif not Extensions_Allowed
and then not Is_Discrete_Type (Exp_Type)
then
Error_Msg_N
("expression in case statement must be of a discrete_Type", Exp);
return;
end if;
-- If the case expression is a formal object of mode in out, then treat
-- it as having a nonstatic subtype by forcing use of the base type
-- (which has to get passed to Check_Case_Choices below). Also use base
-- type when the case expression is parenthesized.
if Paren_Count (Exp) > 0
or else (Is_Entity_Name (Exp)
and then Ekind (Entity (Exp)) = E_Generic_In_Out_Parameter)
then
Exp_Type := Exp_Btype;
end if;
-- Call instantiated procedures to analyze and check discrete choices
Unblocked_Exit_Count := 0;
Analyze_Choices (Alternatives (N), Exp_Type);
Check_Choices (N, Alternatives (N), Exp_Type, Others_Present);
if Is_General_Case_Statement then
-- Work normally done in Process_Statements was deferred; do that
-- deferred work now that Check_Choices has had a chance to create
-- any needed pattern-match-binding declarations.
declare
Alt : Node_Id := First (Alternatives (N));
begin
while Present (Alt) loop
Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
Analyze_Statements (Statements (Alt));
Next (Alt);
end loop;
end;
end if;
if Exp_Type = Universal_Integer and then not Others_Present then
Error_Msg_N ("case on universal integer requires OTHERS choice", Exp);
end if;
-- If all our exits were blocked by unconditional transfers of control,
-- then the entire CASE statement acts as an unconditional transfer of
-- control, so treat it like one, and check unreachable code. Skip this
-- test if we had serious errors preventing any statement analysis.
if Unblocked_Exit_Count = 0 and then Statements_Analyzed then
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
Check_Unreachable_Code (N);
else
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
end if;
-- If the expander is active it will detect the case of a statically
-- determined single alternative and remove warnings for the case, but
-- if we are not doing expansion, that circuit won't be active. Here we
-- duplicate the effect of removing warnings in the same way, so that
-- we will get the same set of warnings in -gnatc mode.
if not Expander_Active
and then Compile_Time_Known_Value (Expression (N))
and then Serious_Errors_Detected = 0
then
declare
Chosen : constant Node_Id := Find_Static_Alternative (N);
Alt : Node_Id;
begin
Alt := First (Alternatives (N));
while Present (Alt) loop
if Alt /= Chosen then
Remove_Warning_Messages (Statements (Alt));
end if;
Next (Alt);
end loop;
end;
end if;
end Analyze_Case_Statement;
----------------------------
-- Analyze_Exit_Statement --
----------------------------
-- If the exit includes a name, it must be the name of a currently open
-- loop. Otherwise there must be an innermost open loop on the stack, to
-- which the statement implicitly refers.
-- Additionally, in SPARK mode:
-- The exit can only name the closest enclosing loop;
-- An exit with a when clause must be directly contained in a loop;
-- An exit without a when clause must be directly contained in an
-- if-statement with no elsif or else, which is itself directly contained
-- in a loop. The exit must be the last statement in the if-statement.
procedure Analyze_Exit_Statement (N : Node_Id) is
Target : constant Node_Id := Name (N);
Cond : constant Node_Id := Condition (N);
Scope_Id : Entity_Id := Empty; -- initialize to prevent warning
U_Name : Entity_Id;
Kind : Entity_Kind;
begin
if No (Cond) then
Check_Unreachable_Code (N);
end if;
if Present (Target) then
Analyze (Target);
U_Name := Entity (Target);
if not In_Open_Scopes (U_Name) or else Ekind (U_Name) /= E_Loop then
Error_Msg_N ("invalid loop name in exit statement", N);
return;
else
Set_Has_Exit (U_Name);
end if;
else
U_Name := Empty;
end if;
for J in reverse 0 .. Scope_Stack.Last loop
Scope_Id := Scope_Stack.Table (J).Entity;
Kind := Ekind (Scope_Id);
if Kind = E_Loop and then (No (Target) or else Scope_Id = U_Name) then
Set_Has_Exit (Scope_Id);
exit;
elsif Kind = E_Block
or else Kind = E_Loop
or else Kind = E_Return_Statement
then
null;
else
Error_Msg_N
("cannot exit from program unit or accept statement", N);
return;
end if;
end loop;
-- Verify that if present the condition is a Boolean expression
if Present (Cond) then
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
end if;
-- Chain exit statement to associated loop entity
Set_Next_Exit_Statement (N, First_Exit_Statement (Scope_Id));
Set_First_Exit_Statement (Scope_Id, N);
-- Since the exit may take us out of a loop, any previous assignment
-- statement is not useless, so clear last assignment indications. It
-- is OK to keep other current values, since if the exit statement
-- does not exit, then the current values are still valid.
Kill_Current_Values (Last_Assignment_Only => True);
end Analyze_Exit_Statement;
----------------------------
-- Analyze_Goto_Statement --
----------------------------
procedure Analyze_Goto_Statement (N : Node_Id) is
Label : constant Node_Id := Name (N);
Scope_Id : Entity_Id;
Label_Scope : Entity_Id;
Label_Ent : Entity_Id;
begin
-- Actual semantic checks
Check_Unreachable_Code (N);
Kill_Current_Values (Last_Assignment_Only => True);
Analyze (Label);
Label_Ent := Entity (Label);
-- Ignore previous error
if Label_Ent = Any_Id then
Check_Error_Detected;
return;
-- We just have a label as the target of a goto
elsif Ekind (Label_Ent) /= E_Label then
Error_Msg_N ("target of goto statement must be a label", Label);
return;
-- Check that the target of the goto is reachable according to Ada
-- scoping rules. Note: the special gotos we generate for optimizing
-- local handling of exceptions would violate these rules, but we mark
-- such gotos as analyzed when built, so this code is never entered.
elsif not Reachable (Label_Ent) then
Error_Msg_N ("target of goto statement is not reachable", Label);
return;
end if;
-- Here if goto passes initial validity checks
Label_Scope := Enclosing_Scope (Label_Ent);
for J in reverse 0 .. Scope_Stack.Last loop
Scope_Id := Scope_Stack.Table (J).Entity;
if Label_Scope = Scope_Id
or else Ekind (Scope_Id) not in
E_Block | E_Loop | E_Return_Statement
then
if Scope_Id /= Label_Scope then
Error_Msg_N
("cannot exit from program unit or accept statement", N);
end if;
return;
end if;
end loop;
raise Program_Error;
end Analyze_Goto_Statement;
---------------------------------
-- Analyze_Goto_When_Statement --
---------------------------------
procedure Analyze_Goto_When_Statement (N : Node_Id) is
begin
-- Verify the condition is a Boolean expression
Analyze_And_Resolve (Condition (N), Any_Boolean);
Check_Unset_Reference (Condition (N));
end Analyze_Goto_When_Statement;
--------------------------
-- Analyze_If_Statement --
--------------------------
-- A special complication arises in the analysis of if statements
-- The expander has circuitry to completely delete code that it can tell
-- will not be executed (as a result of compile time known conditions). In
-- the analyzer, we ensure that code that will be deleted in this manner
-- is analyzed but not expanded. This is obviously more efficient, but
-- more significantly, difficulties arise if code is expanded and then
-- eliminated (e.g. exception table entries disappear). Similarly, itypes
-- generated in deleted code must be frozen from start, because the nodes
-- on which they depend will not be available at the freeze point.
procedure Analyze_If_Statement (N : Node_Id) is
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
-- Recursively save value of this global, will be restored on exit
Save_In_Deleted_Code : Boolean := In_Deleted_Code;
Del : Boolean := False;
-- This flag gets set True if a True condition has been found, which
-- means that remaining ELSE/ELSIF parts are deleted.
procedure Analyze_Cond_Then (Cnode : Node_Id);
-- This is applied to either the N_If_Statement node itself or to an
-- N_Elsif_Part node. It deals with analyzing the condition and the THEN
-- statements associated with it.
-----------------------
-- Analyze_Cond_Then --
-----------------------
procedure Analyze_Cond_Then (Cnode : Node_Id) is
Cond : constant Node_Id := Condition (Cnode);
Tstm : constant List_Id := Then_Statements (Cnode);
begin
Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
Set_Current_Value_Condition (Cnode);
-- If already deleting, then just analyze then statements
if Del then
Analyze_Statements (Tstm);
-- Compile time known value, not deleting yet
elsif Compile_Time_Known_Value (Cond) then
Save_In_Deleted_Code := In_Deleted_Code;
-- If condition is True, then analyze the THEN statements and set
-- no expansion for ELSE and ELSIF parts.
if Is_True (Expr_Value (Cond)) then
Analyze_Statements (Tstm);
Del := True;
Expander_Mode_Save_And_Set (False);
In_Deleted_Code := True;
-- If condition is False, analyze THEN with expansion off
else pragma Assert (Is_False (Expr_Value (Cond)));
Expander_Mode_Save_And_Set (False);
In_Deleted_Code := True;
Analyze_Statements (Tstm);
Expander_Mode_Restore;
In_Deleted_Code := Save_In_Deleted_Code;
end if;
-- Not known at compile time, not deleting, normal analysis
else
Analyze_Statements (Tstm);
end if;
end Analyze_Cond_Then;
-- Local variables
E : Node_Id;
-- For iterating over elsif parts
-- Start of processing for Analyze_If_Statement
begin
-- Initialize exit count for else statements. If there is no else part,
-- this count will stay non-zero reflecting the fact that the uncovered
-- else case is an unblocked exit.
Unblocked_Exit_Count := 1;
Analyze_Cond_Then (N);
-- Now to analyze the elsif parts if any are present
if Present (Elsif_Parts (N)) then
E := First (Elsif_Parts (N));
while Present (E) loop
Analyze_Cond_Then (E);
Next (E);
end loop;
end if;
if Present (Else_Statements (N)) then
Analyze_Statements (Else_Statements (N));
end if;
-- If all our exits were blocked by unconditional transfers of control,
-- then the entire IF statement acts as an unconditional transfer of
-- control, so treat it like one, and check unreachable code.
if Unblocked_Exit_Count = 0 then
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
Check_Unreachable_Code (N);
else
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
end if;
if Del then
Expander_Mode_Restore;
In_Deleted_Code := Save_In_Deleted_Code;
end if;
if not Expander_Active
and then Compile_Time_Known_Value (Condition (N))
and then Serious_Errors_Detected = 0
then
if Is_True (Expr_Value (Condition (N))) then
Remove_Warning_Messages (Else_Statements (N));
if Present (Elsif_Parts (N)) then
E := First (Elsif_Parts (N));
while Present (E) loop
Remove_Warning_Messages (Then_Statements (E));
Next (E);
end loop;
end if;
else
Remove_Warning_Messages (Then_Statements (N));
end if;
end if;
-- Warn on redundant if statement that has no effect
-- Note, we could also check empty ELSIF parts ???
if Warn_On_Redundant_Constructs
-- If statement must be from source
and then Comes_From_Source (N)
-- Condition must not have obvious side effect
and then Has_No_Obvious_Side_Effects (Condition (N))
-- No elsif parts of else part
and then No (Elsif_Parts (N))
and then No (Else_Statements (N))
-- Then must be a single null statement
and then List_Length (Then_Statements (N)) = 1
then
-- Go to original node, since we may have rewritten something as
-- a null statement (e.g. a case we could figure the outcome of).
declare
T : constant Node_Id := First (Then_Statements (N));
S : constant Node_Id := Original_Node (T);
begin
if Comes_From_Source (S) and then Nkind (S) = N_Null_Statement then
Error_Msg_N ("if statement has no effect?r?", N);
end if;
end;
end if;
end Analyze_If_Statement;
----------------------------------------
-- Analyze_Implicit_Label_Declaration --
----------------------------------------
-- An implicit label declaration is generated in the innermost enclosing
-- declarative part. This is done for labels, and block and loop names.
-- Note: any changes in this routine may need to be reflected in
-- Analyze_Label_Entity.
procedure Analyze_Implicit_Label_Declaration (N : Node_Id) is
Id : constant Node_Id := Defining_Identifier (N);
begin
Enter_Name (Id);
Mutate_Ekind (Id, E_Label);
Set_Etype (Id, Standard_Void_Type);
Set_Enclosing_Scope (Id, Current_Scope);
end Analyze_Implicit_Label_Declaration;
------------------------------
-- Analyze_Iteration_Scheme --
------------------------------
procedure Analyze_Iteration_Scheme (N : Node_Id) is
Cond : Node_Id;
Iter_Spec : Node_Id;
Loop_Spec : Node_Id;
begin
-- For an infinite loop, there is no iteration scheme
if No (N) then
return;
end if;
Cond := Condition (N);
Iter_Spec := Iterator_Specification (N);
Loop_Spec := Loop_Parameter_Specification (N);
if Present (Cond) then
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
Set_Current_Value_Condition (N);
elsif Present (Iter_Spec) then
Analyze_Iterator_Specification (Iter_Spec);
else
Analyze_Loop_Parameter_Specification (Loop_Spec);
end if;
end Analyze_Iteration_Scheme;
------------------------------------
-- Analyze_Iterator_Specification --
------------------------------------
procedure Analyze_Iterator_Specification (N : Node_Id) is
Def_Id : constant Node_Id := Defining_Identifier (N);
Iter_Name : constant Node_Id := Name (N);
Loc : constant Source_Ptr := Sloc (N);
Subt : constant Node_Id := Subtype_Indication (N);
Bas : Entity_Id := Empty; -- initialize to prevent warning
Typ : Entity_Id;
procedure Check_Reverse_Iteration (Typ : Entity_Id);
-- For an iteration over a container, if the loop carries the Reverse
-- indicator, verify that the container type has an Iterate aspect that
-- implements the reversible iterator interface.
procedure Check_Subtype_Definition (Comp_Type : Entity_Id);
-- If a subtype indication is present, verify that it is consistent
-- with the component type of the array or container name.
-- In Ada 2022, the subtype indication may be an access definition,
-- if the array or container has elements of an anonymous access type.
function Get_Cursor_Type (Typ : Entity_Id) return Entity_Id;
-- For containers with Iterator and related aspects, the cursor is
-- obtained by locating an entity with the proper name in the scope
-- of the type.
-----------------------------
-- Check_Reverse_Iteration --
-----------------------------
procedure Check_Reverse_Iteration (Typ : Entity_Id) is
begin
if Reverse_Present (N) then
if Is_Array_Type (Typ)
or else Is_Reversible_Iterator (Typ)
or else
(Present (Find_Aspect (Typ, Aspect_Iterable))
and then
Present
(Get_Iterable_Type_Primitive (Typ, Name_Previous)))
then
null;
else
Error_Msg_N
("container type does not support reverse iteration", N);
end if;
end if;
end Check_Reverse_Iteration;
-------------------------------
-- Check_Subtype_Definition --
-------------------------------
procedure Check_Subtype_Definition (Comp_Type : Entity_Id) is
begin
if not Present (Subt) then
return;
end if;
if Is_Anonymous_Access_Type (Entity (Subt)) then
if not Is_Anonymous_Access_Type (Comp_Type) then
Error_Msg_NE
("component type& is not an anonymous access",
Subt, Comp_Type);
elsif not Conforming_Types
(Designated_Type (Entity (Subt)),
Designated_Type (Comp_Type),
Fully_Conformant)
then
Error_Msg_NE
("subtype indication does not match component type&",
Subt, Comp_Type);
end if;
elsif Present (Subt)
and then (not Covers (Base_Type (Bas), Comp_Type)
or else not Subtypes_Statically_Match (Bas, Comp_Type))
then
if Is_Array_Type (Typ) then
Error_Msg_NE
("subtype indication does not match component type&",
Subt, Comp_Type);
else
Error_Msg_NE
("subtype indication does not match element type&",
Subt, Comp_Type);
end if;
end if;
end Check_Subtype_Definition;
---------------------
-- Get_Cursor_Type --
---------------------
function Get_Cursor_Type (Typ : Entity_Id) return Entity_Id is
Ent : Entity_Id;
begin
-- If iterator type is derived, the cursor is declared in the scope
-- of the parent type.
if Is_Derived_Type (Typ) then
Ent := First_Entity (Scope (Etype (Typ)));
else
Ent := First_Entity (Scope (Typ));
end if;
while Present (Ent) loop
exit when Chars (Ent) = Name_Cursor;
Next_Entity (Ent);
end loop;
if No (Ent) then
return Any_Type;
end if;
-- The cursor is the target of generated assignments in the
-- loop, and cannot have a limited type.
if Is_Limited_Type (Etype (Ent)) then
Error_Msg_N ("cursor type cannot be limited", N);
end if;
return Etype (Ent);
end Get_Cursor_Type;
-- Start of processing for Analyze_Iterator_Specification
begin
Enter_Name (Def_Id);
-- AI12-0151 specifies that when the subtype indication is present, it
-- must statically match the type of the array or container element.
-- To simplify this check, we introduce a subtype declaration with the
-- given subtype indication when it carries a constraint, and rewrite
-- the original as a reference to the created subtype entity.
if Present (Subt) then
if Nkind (Subt) = N_Subtype_Indication then
declare
S : constant Entity_Id := Make_Temporary (Sloc (Subt), 'S');
Decl : constant Node_Id :=
Make_Subtype_Declaration (Loc,
Defining_Identifier => S,
Subtype_Indication => New_Copy_Tree (Subt));
begin
Insert_Before (Parent (Parent (N)), Decl);
Analyze (Decl);
Rewrite (Subt, New_Occurrence_Of (S, Sloc (Subt)));
end;
-- Ada 2022: the subtype definition may be for an anonymous
-- access type.
elsif Nkind (Subt) = N_Access_Definition then
declare
S : constant Entity_Id := Make_Temporary (Sloc (Subt), 'S');
Decl : Node_Id;
begin
if Present (Subtype_Mark (Subt)) then
Decl :=
Make_Full_Type_Declaration (Loc,
Defining_Identifier => S,
Type_Definition =>
Make_Access_To_Object_Definition (Loc,
All_Present => True,
Subtype_Indication =>
New_Copy_Tree (Subtype_Mark (Subt))));
else
Decl :=
Make_Full_Type_Declaration (Loc,
Defining_Identifier => S,
Type_Definition =>
New_Copy_Tree
(Access_To_Subprogram_Definition (Subt)));
end if;
Insert_Before (Parent (Parent (N)), Decl);
Analyze (Decl);
Freeze_Before (First (Statements (Parent (Parent (N)))), S);
Rewrite (Subt, New_Occurrence_Of (S, Sloc (Subt)));
end;
else
Analyze (Subt);
end if;
-- Save entity of subtype indication for subsequent check
Bas := Entity (Subt);
end if;
Preanalyze_Range (Iter_Name);
-- If the domain of iteration is a function call, make sure the function
-- itself is frozen. This is an issue if this is a local expression
-- function.
if Nkind (Iter_Name) = N_Function_Call
and then Is_Entity_Name (Name (Iter_Name))
and then Full_Analysis
and then (In_Assertion_Expr = 0 or else Assertions_Enabled)
then
Freeze_Before (N, Entity (Name (Iter_Name)));
end if;
-- Set the kind of the loop variable, which is not visible within the
-- iterator name.
Mutate_Ekind (Def_Id, E_Variable);
-- Provide a link between the iterator variable and the container, for
-- subsequent use in cross-reference and modification information.
if Of_Present (N) then
Set_Related_Expression (Def_Id, Iter_Name);
-- For a container, the iterator is specified through the aspect
if not Is_Array_Type (Etype (Iter_Name)) then
declare
Iterator : constant Entity_Id :=
Find_Value_Of_Aspect
(Etype (Iter_Name), Aspect_Default_Iterator);
I : Interp_Index;
It : Interp;
begin
-- The domain of iteration must implement either the RM
-- iterator interface, or the SPARK Iterable aspect.
if No (Iterator) then
if No (Find_Aspect (Etype (Iter_Name), Aspect_Iterable)) then
Error_Msg_NE
("cannot iterate over&",
N, Base_Type (Etype (Iter_Name)));
return;
end if;
elsif not Is_Overloaded (Iterator) then
Check_Reverse_Iteration (Etype (Iterator));
-- If Iterator is overloaded, use reversible iterator if one is
-- available.
elsif Is_Overloaded (Iterator) then
Get_First_Interp (Iterator, I, It);
while Present (It.Nam) loop
if Ekind (It.Nam) = E_Function
and then Is_Reversible_Iterator (Etype (It.Nam))
then
Set_Etype (Iterator, It.Typ);
Set_Entity (Iterator, It.Nam);
exit;
end if;
Get_Next_Interp (I, It);
end loop;
Check_Reverse_Iteration (Etype (Iterator));
end if;
end;
end if;
end if;
-- If the domain of iteration is an expression, create a declaration for
-- it, so that finalization actions are introduced outside of the loop.
-- The declaration must be a renaming (both in GNAT and GNATprove
-- modes), because the body of the loop may assign to elements.
if not Is_Entity_Name (Iter_Name)
-- When the context is a quantified expression, the renaming
-- declaration is delayed until the expansion phase if we are
-- doing expansion.
and then (Nkind (Parent (N)) /= N_Quantified_Expression
or else (Operating_Mode = Check_Semantics
and then not GNATprove_Mode))
-- Do not perform this expansion when expansion is disabled, where the
-- temporary may hide the transformation of a selected component into
-- a prefixed function call, and references need to see the original
-- expression.
and then (Expander_Active or GNATprove_Mode)
then
declare
Id : constant Entity_Id := Make_Temporary (Loc, 'R', Iter_Name);
Decl : Node_Id;
Act_S : Node_Id;
begin
-- If the domain of iteration is an array component that depends
-- on a discriminant, create actual subtype for it. Preanalysis
-- does not generate the actual subtype of a selected component.
if Nkind (Iter_Name) = N_Selected_Component
and then Is_Array_Type (Etype (Iter_Name))
then
Act_S :=
Build_Actual_Subtype_Of_Component
(Etype (Selector_Name (Iter_Name)), Iter_Name);
Insert_Action (N, Act_S);
if Present (Act_S) then
Typ := Defining_Identifier (Act_S);
else
Typ := Etype (Iter_Name);
end if;
else
Typ := Etype (Iter_Name);
-- Verify that the expression produces an iterator
if not Of_Present (N) and then not Is_Iterator (Typ)
and then not Is_Array_Type (Typ)
and then No (Find_Aspect (Typ, Aspect_Iterable))
then
Error_Msg_N
("expect object that implements iterator interface",
Iter_Name);
end if;
end if;
-- Protect against malformed iterator
if Typ = Any_Type then
Error_Msg_N ("invalid expression in loop iterator", Iter_Name);
return;
end if;
if not Of_Present (N) then
Check_Reverse_Iteration (Typ);
end if;
-- For an element iteration over a slice, we must complete
-- the resolution and expansion of the slice bounds. These
-- can be arbitrary expressions, and the preanalysis that
-- was performed in preparation for the iteration may have
-- generated an itype whose bounds must be fully expanded.
-- We set the parent node to provide a proper insertion
-- point for generated actions, if any.
if Nkind (Iter_Name) = N_Slice
and then Nkind (Discrete_Range (Iter_Name)) = N_Range
and then not Analyzed (Discrete_Range (Iter_Name))
then
declare
Indx : constant Node_Id :=
Entity (First_Index (Etype (Iter_Name)));
begin
Set_Parent (Indx, Iter_Name);
Resolve (Scalar_Range (Indx), Etype (Indx));
end;
end if;
-- The name in the renaming declaration may be a function call.
-- Indicate that it does not come from source, to suppress
-- spurious warnings on renamings of parameterless functions,
-- a common enough idiom in user-defined iterators.
Decl :=
Make_Object_Renaming_Declaration (Loc,
Defining_Identifier => Id,
Subtype_Mark => New_Occurrence_Of (Typ, Loc),
Name =>
New_Copy_Tree (Iter_Name, New_Sloc => Loc));
Insert_Actions (Parent (Parent (N)), New_List (Decl));
Rewrite (Name (N), New_Occurrence_Of (Id, Loc));
Analyze (Name (N));
Set_Etype (Id, Typ);
Set_Etype (Name (N), Typ);
end;
-- Container is an entity or an array with uncontrolled components, or
-- else it is a container iterator given by a function call, typically
-- called Iterate in the case of predefined containers, even though
-- Iterate is not a reserved name. What matters is that the return type
-- of the function is an iterator type.
elsif Is_Entity_Name (Iter_Name) then
Analyze (Iter_Name);
if Nkind (Iter_Name) = N_Function_Call then
declare
C : constant Node_Id := Name (Iter_Name);
I : Interp_Index;
It : Interp;
begin
if not Is_Overloaded (Iter_Name) then
Resolve (Iter_Name, Etype (C));
else
Get_First_Interp (C, I, It);
while It.Typ /= Empty loop
if Reverse_Present (N) then
if Is_Reversible_Iterator (It.Typ) then
Resolve (Iter_Name, It.Typ);
exit;
end if;
elsif Is_Iterator (It.Typ) then
Resolve (Iter_Name, It.Typ);
exit;
end if;
Get_Next_Interp (I, It);
end loop;
end if;
end;
-- Domain of iteration is not overloaded
else
Resolve (Iter_Name);
end if;
if not Of_Present (N) then
Check_Reverse_Iteration (Etype (Iter_Name));
end if;
end if;
-- Get base type of container, for proper retrieval of Cursor type
-- and primitive operations.
Typ := Base_Type (Etype (Iter_Name));
if Is_Array_Type (Typ) then
if Of_Present (N) then
Set_Etype (Def_Id, Component_Type (Typ));
-- The loop variable is aliased if the array components are
-- aliased. Likewise for the independent aspect.
Set_Is_Aliased (Def_Id, Has_Aliased_Components (Typ));
Set_Is_Independent (Def_Id, Has_Independent_Components (Typ));
-- AI12-0047 stipulates that the domain (array or container)
-- cannot be a component that depends on a discriminant if the
-- enclosing object is mutable, to prevent a modification of the
-- domain of iteration in the course of an iteration.
-- If the object is an expression it has been captured in a
-- temporary, so examine original node.
if Nkind (Original_Node (Iter_Name)) = N_Selected_Component
and then Is_Dependent_Component_Of_Mutable_Object
(Original_Node (Iter_Name))
then
Error_Msg_N
("iterable name cannot be a discriminant-dependent "
& "component of a mutable object", N);
end if;
Check_Subtype_Definition (Component_Type (Typ));
-- Here we have a missing Range attribute
else
Error_Msg_N
("missing Range attribute in iteration over an array", N);
-- In Ada 2012 mode, this may be an attempt at an iterator
if Ada_Version >= Ada_2012 then
Error_Msg_NE
("\if& is meant to designate an element of the array, use OF",
N, Def_Id);
end if;
-- Prevent cascaded errors
Mutate_Ekind (Def_Id, E_Loop_Parameter);
Set_Etype (Def_Id, Etype (First_Index (Typ)));
end if;
-- Check for type error in iterator
elsif Typ = Any_Type then
return;
-- Iteration over a container
else
Mutate_Ekind (Def_Id, E_Loop_Parameter);
Error_Msg_Ada_2012_Feature ("container iterator", Sloc (N));
-- OF present
if Of_Present (N) then
if Has_Aspect (Typ, Aspect_Iterable) then
declare
Elt : constant Entity_Id :=
Get_Iterable_Type_Primitive (Typ, Name_Element);
begin
if No (Elt) then
Error_Msg_N
("missing Element primitive for iteration", N);
else
Set_Etype (Def_Id, Etype (Elt));
Check_Reverse_Iteration (Typ);
end if;
end;
Check_Subtype_Definition (Etype (Def_Id));
-- For a predefined container, the type of the loop variable is
-- the Iterator_Element aspect of the container type.
else
declare
Element : constant Entity_Id :=
Find_Value_Of_Aspect
(Typ, Aspect_Iterator_Element);
Iterator : constant Entity_Id :=
Find_Value_Of_Aspect
(Typ, Aspect_Default_Iterator);
Orig_Iter_Name : constant Node_Id :=
Original_Node (Iter_Name);
Cursor_Type : Entity_Id;
begin
if No (Element) then
Error_Msg_NE ("cannot iterate over&", N, Typ);
return;
else
Set_Etype (Def_Id, Entity (Element));
Cursor_Type := Get_Cursor_Type (Typ);
pragma Assert (Present (Cursor_Type));
Check_Subtype_Definition (Etype (Def_Id));
-- If the container has a variable indexing aspect, the
-- element is a variable and is modifiable in the loop.
if Has_Aspect (Typ, Aspect_Variable_Indexing) then
Mutate_Ekind (Def_Id, E_Variable);
end if;
-- If the container is a constant, iterating over it
-- requires a Constant_Indexing operation.
if not Is_Variable (Iter_Name)
and then not Has_Aspect (Typ, Aspect_Constant_Indexing)
then
Error_Msg_N
("iteration over constant container require "
& "constant_indexing aspect", N);
-- The Iterate function may have an in_out parameter,
-- and a constant container is thus illegal.
elsif Present (Iterator)
and then Ekind (Entity (Iterator)) = E_Function
and then Ekind (First_Formal (Entity (Iterator))) /=
E_In_Parameter
and then not Is_Variable (Iter_Name)
then
Error_Msg_N ("variable container expected", N);
end if;
-- Detect a case where the iterator denotes a component
-- of a mutable object which depends on a discriminant.
-- Note that the iterator may denote a function call in
-- qualified form, in which case this check should not
-- be performed.
if Nkind (Orig_Iter_Name) = N_Selected_Component
and then
Present (Entity (Selector_Name (Orig_Iter_Name)))
and then
Ekind (Entity (Selector_Name (Orig_Iter_Name))) in
E_Component | E_Discriminant
and then Is_Dependent_Component_Of_Mutable_Object
(Orig_Iter_Name)
then
Error_Msg_N
("container cannot be a discriminant-dependent "
& "component of a mutable object", N);
end if;
end if;
end;
end if;
-- IN iterator, domain is a range, or a call to Iterate function
else
-- For an iteration of the form IN, the name must denote an
-- iterator, typically the result of a call to Iterate. Give a
-- useful error message when the name is a container by itself.
-- The type may be a formal container type, which has to have
-- an Iterable aspect detailing the required primitives.
if Is_Entity_Name (Original_Node (Name (N)))
and then not Is_Iterator (Typ)
then
if Has_Aspect (Typ, Aspect_Iterable) then
null;
elsif not Has_Aspect (Typ, Aspect_Iterator_Element) then
Error_Msg_NE
("cannot iterate over&", Name (N), Typ);
else
Error_Msg_N
("name must be an iterator, not a container", Name (N));
end if;
if Has_Aspect (Typ, Aspect_Iterable) then
null;
else
Error_Msg_NE
("\to iterate directly over the elements of a container, "
& "write `of &`", Name (N), Original_Node (Name (N)));
-- No point in continuing analysis of iterator spec
return;
end if;
end if;
-- If the name is a call (typically prefixed) to some Iterate
-- function, it has been rewritten as an object declaration.
-- If that object is a selected component, verify that it is not
-- a component of an unconstrained mutable object.
if Nkind (Iter_Name) = N_Identifier
or else (not Expander_Active and Comes_From_Source (Iter_Name))
then
declare
Orig_Node : constant Node_Id := Original_Node (Iter_Name);
Iter_Kind : constant Node_Kind := Nkind (Orig_Node);
Obj : Node_Id;
begin
if Iter_Kind = N_Selected_Component then
Obj := Prefix (Orig_Node);
elsif Iter_Kind = N_Function_Call then
Obj := First_Actual (Orig_Node);
-- If neither, the name comes from source
else
Obj := Iter_Name;
end if;
if Nkind (Obj) = N_Selected_Component
and then Is_Dependent_Component_Of_Mutable_Object (Obj)
then
Error_Msg_N
("container cannot be a discriminant-dependent "
& "component of a mutable object", N);
end if;
end;
end if;
-- The result type of Iterate function is the classwide type of
-- the interface parent. We need the specific Cursor type defined
-- in the container package. We obtain it by name for a predefined
-- container, or through the Iterable aspect for a formal one.
if Has_Aspect (Typ, Aspect_Iterable) then
Set_Etype (Def_Id,
Get_Cursor_Type
(Parent (Find_Value_Of_Aspect (Typ, Aspect_Iterable)),
Typ));
else
Set_Etype (Def_Id, Get_Cursor_Type (Typ));
Check_Reverse_Iteration (Etype (Iter_Name));
end if;
end if;
end if;
if Present (Iterator_Filter (N)) then
-- Preanalyze the filter. Expansion will take place when enclosing
-- loop is expanded.
Preanalyze_And_Resolve (Iterator_Filter (N), Standard_Boolean);
end if;
end Analyze_Iterator_Specification;
-------------------
-- Analyze_Label --
-------------------
-- Note: the semantic work required for analyzing labels (setting them as
-- reachable) was done in a prepass through the statements in the block,
-- so that forward gotos would be properly handled. See Analyze_Statements
-- for further details. The only processing required here is to deal with
-- optimizations that depend on an assumption of sequential control flow,
-- since of course the occurrence of a label breaks this assumption.
procedure Analyze_Label (N : Node_Id) is
pragma Warnings (Off, N);
begin
Kill_Current_Values;
end Analyze_Label;
--------------------------
-- Analyze_Label_Entity --
--------------------------
procedure Analyze_Label_Entity (E : Entity_Id) is
begin
Mutate_Ekind (E, E_Label);
Set_Etype (E, Standard_Void_Type);
Set_Enclosing_Scope (E, Current_Scope);
Set_Reachable (E, True);
end Analyze_Label_Entity;
------------------------------------------
-- Analyze_Loop_Parameter_Specification --
------------------------------------------
procedure Analyze_Loop_Parameter_Specification (N : Node_Id) is
Loop_Nod : constant Node_Id := Parent (Parent (N));
procedure Check_Controlled_Array_Attribute (DS : Node_Id);
-- If the bounds are given by a 'Range reference on a function call
-- that returns a controlled array, introduce an explicit declaration
-- to capture the bounds, so that the function result can be finalized
-- in timely fashion.
procedure Check_Predicate_Use (T : Entity_Id);
-- Diagnose Attempt to iterate through non-static predicate. Note that
-- a type with inherited predicates may have both static and dynamic
-- forms. In this case it is not sufficent to check the static predicate
-- function only, look for a dynamic predicate aspect as well.
procedure Process_Bounds (R : Node_Id);
-- If the iteration is given by a range, create temporaries and
-- assignment statements block to capture the bounds and perform
-- required finalization actions in case a bound includes a function
-- call that uses the temporary stack. We first preanalyze a copy of
-- the range in order to determine the expected type, and analyze and
-- resolve the original bounds.
--------------------------------------
-- Check_Controlled_Array_Attribute --
--------------------------------------
procedure Check_Controlled_Array_Attribute (DS : Node_Id) is
begin
if Nkind (DS) = N_Attribute_Reference
and then Is_Entity_Name (Prefix (DS))
and then Ekind (Entity (Prefix (DS))) = E_Function
and then Is_Array_Type (Etype (Entity (Prefix (DS))))
and then
Is_Controlled (Component_Type (Etype (Entity (Prefix (DS)))))
and then Expander_Active
then
declare
Loc : constant Source_Ptr := Sloc (N);
Arr : constant Entity_Id := Etype (Entity (Prefix (DS)));
Indx : constant Entity_Id :=
Base_Type (Etype (First_Index (Arr)));
Subt : constant Entity_Id := Make_Temporary (Loc, 'S');
Decl : Node_Id;
begin
Decl :=
Make_Subtype_Declaration (Loc,
Defining_Identifier => Subt,
Subtype_Indication =>
Make_Subtype_Indication (Loc,
Subtype_Mark => New_Occurrence_Of (Indx, Loc),
Constraint =>
Make_Range_Constraint (Loc, Relocate_Node (DS))));
Insert_Before (Loop_Nod, Decl);
Analyze (Decl);
Rewrite (DS,
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Subt, Loc),
Attribute_Name => Attribute_Name (DS)));
Analyze (DS);
end;
end if;
end Check_Controlled_Array_Attribute;
-------------------------
-- Check_Predicate_Use --
-------------------------
procedure Check_Predicate_Use (T : Entity_Id) is
begin
-- A predicated subtype is illegal in loops and related constructs
-- if the predicate is not static, or if it is a non-static subtype
-- of a statically predicated subtype.
if Is_Discrete_Type (T)
and then Has_Predicates (T)
and then (not Has_Static_Predicate (T)
or else not Is_Static_Subtype (T)
or else Has_Dynamic_Predicate_Aspect (T))
then
-- Seems a confusing message for the case of a static predicate
-- with a non-static subtype???
Bad_Predicated_Subtype_Use
("cannot use subtype& with non-static predicate for loop "
& "iteration", Discrete_Subtype_Definition (N),
T, Suggest_Static => True);
elsif Inside_A_Generic
and then Is_Generic_Formal (T)
and then Is_Discrete_Type (T)
then
Set_No_Dynamic_Predicate_On_Actual (T);
end if;
end Check_Predicate_Use;
--------------------
-- Process_Bounds --
--------------------
procedure Process_Bounds (R : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
function One_Bound
(Original_Bound : Node_Id;
Analyzed_Bound : Node_Id;
Typ : Entity_Id) return Node_Id;
-- Capture value of bound and return captured value
---------------
-- One_Bound --
---------------
function One_Bound
(Original_Bound : Node_Id;
Analyzed_Bound : Node_Id;
Typ : Entity_Id) return Node_Id
is
Assign : Node_Id;
Decl : Node_Id;
Id : Entity_Id;
begin
-- If the bound is a constant or an object, no need for a separate
-- declaration. If the bound is the result of previous expansion
-- it is already analyzed and should not be modified. Note that
-- the Bound will be resolved later, if needed, as part of the
-- call to Make_Index (literal bounds may need to be resolved to
-- type Integer).
if Analyzed (Original_Bound) then
return Original_Bound;
elsif Nkind (Analyzed_Bound) in
N_Integer_Literal | N_Character_Literal
or else Is_Entity_Name (Analyzed_Bound)
then
Analyze_And_Resolve (Original_Bound, Typ);
return Original_Bound;
elsif Inside_Class_Condition_Preanalysis then
Analyze_And_Resolve (Original_Bound, Typ);
return Original_Bound;
end if;
-- Normally, the best approach is simply to generate a constant
-- declaration that captures the bound. However, there is a nasty
-- case where this is wrong. If the bound is complex, and has a
-- possible use of the secondary stack, we need to generate a
-- separate assignment statement to ensure the creation of a block
-- which will release the secondary stack.
-- We prefer the constant declaration, since it leaves us with a
-- proper trace of the value, useful in optimizations that get rid
-- of junk range checks.
if not Has_Sec_Stack_Call (Analyzed_Bound) then
Analyze_And_Resolve (Original_Bound, Typ);
-- Ensure that the bound is valid. This check should not be
-- generated when the range belongs to a quantified expression
-- as the construct is still not expanded into its final form.
if Nkind (Parent (R)) /= N_Loop_Parameter_Specification
or else Nkind (Parent (Parent (R))) /= N_Quantified_Expression
then
Ensure_Valid (Original_Bound);
end if;
Force_Evaluation (Original_Bound);
return Original_Bound;
end if;
Id := Make_Temporary (Loc, 'R', Original_Bound);
-- Here we make a declaration with a separate assignment
-- statement, and insert before loop header.
Decl :=
Make_Object_Declaration (Loc,
Defining_Identifier => Id,
Object_Definition => New_Occurrence_Of (Typ, Loc));
Assign :=
Make_Assignment_Statement (Loc,
Name => New_Occurrence_Of (Id, Loc),
Expression => Relocate_Node (Original_Bound));
Insert_Actions (Loop_Nod, New_List (Decl, Assign));
-- Now that this temporary variable is initialized we decorate it
-- as safe-to-reevaluate to inform to the backend that no further
-- asignment will be issued and hence it can be handled as side
-- effect free. Note that this decoration must be done when the
-- assignment has been analyzed because otherwise it will be
-- rejected (see Analyze_Assignment).
Set_Is_Safe_To_Reevaluate (Id);
Rewrite (Original_Bound, New_Occurrence_Of (Id, Loc));
if Nkind (Assign) = N_Assignment_Statement then
return Expression (Assign);
else
return Original_Bound;
end if;
end One_Bound;
Hi : constant Node_Id := High_Bound (R);
Lo : constant Node_Id := Low_Bound (R);
R_Copy : constant Node_Id := New_Copy_Tree (R);
New_Hi : Node_Id;
New_Lo : Node_Id;
Typ : Entity_Id;
-- Start of processing for Process_Bounds
begin
Set_Parent (R_Copy, Parent (R));
Preanalyze_Range (R_Copy);
Typ := Etype (R_Copy);
-- If the type of the discrete range is Universal_Integer, then the
-- bound's type must be resolved to Integer, and any object used to
-- hold the bound must also have type Integer, unless the literal
-- bounds are constant-folded expressions with a user-defined type.
if Typ = Universal_Integer then
if Nkind (Lo) = N_Integer_Literal
and then Present (Etype (Lo))
and then Scope (Etype (Lo)) /= Standard_Standard
then
Typ := Etype (Lo);
elsif Nkind (Hi) = N_Integer_Literal
and then Present (Etype (Hi))
and then Scope (Etype (Hi)) /= Standard_Standard
then
Typ := Etype (Hi);
else
Typ := Standard_Integer;
end if;
end if;
Set_Etype (R, Typ);
New_Lo := One_Bound (Lo, Low_Bound (R_Copy), Typ);
New_Hi := One_Bound (Hi, High_Bound (R_Copy), Typ);
-- Propagate staticness to loop range itself, in case the
-- corresponding subtype is static.
if New_Lo /= Lo and then Is_OK_Static_Expression (New_Lo) then
Rewrite (Low_Bound (R), New_Copy (New_Lo));
end if;
if New_Hi /= Hi and then Is_OK_Static_Expression (New_Hi) then
Rewrite (High_Bound (R), New_Copy (New_Hi));
end if;
end Process_Bounds;
-- Local variables
DS : constant Node_Id := Discrete_Subtype_Definition (N);
Id : constant Entity_Id := Defining_Identifier (N);
DS_Copy : Node_Id;
-- Start of processing for Analyze_Loop_Parameter_Specification
begin
Enter_Name (Id);
-- We always consider the loop variable to be referenced, since the loop
-- may be used just for counting purposes.
Generate_Reference (Id, N, ' ');
-- Check for the case of loop variable hiding a local variable (used
-- later on to give a nice warning if the hidden variable is never
-- assigned).
declare
H : constant Entity_Id := Homonym (Id);
begin
if Present (H)
and then Ekind (H) = E_Variable
and then Is_Discrete_Type (Etype (H))
and then Enclosing_Dynamic_Scope (H) = Enclosing_Dynamic_Scope (Id)
then
Set_Hiding_Loop_Variable (H, Id);
end if;
end;
-- Analyze the subtype definition and create temporaries for the bounds.
-- Do not evaluate the range when preanalyzing a quantified expression
-- because bounds expressed as function calls with side effects will be
-- incorrectly replicated.
if Nkind (DS) = N_Range
and then Expander_Active
and then Nkind (Parent (N)) /= N_Quantified_Expression
then
Process_Bounds (DS);
-- Either the expander not active or the range of iteration is a subtype
-- indication, an entity, or a function call that yields an aggregate or
-- a container.
else
DS_Copy := New_Copy_Tree (DS);
Set_Parent (DS_Copy, Parent (DS));
Preanalyze_Range (DS_Copy);
-- Ada 2012: If the domain of iteration is:
-- a) a function call,
-- b) an identifier that is not a type,
-- c) an attribute reference 'Old (within a postcondition),
-- d) an unchecked conversion or a qualified expression with
-- the proper iterator type.
-- then it is an iteration over a container. It was classified as
-- a loop specification by the parser, and must be rewritten now
-- to activate container iteration. The last case will occur within
-- an expanded inlined call, where the expansion wraps an actual in
-- an unchecked conversion when needed. The expression of the
-- conversion is always an object.
if Nkind (DS_Copy) = N_Function_Call
or else (Is_Entity_Name (DS_Copy)
and then not Is_Type (Entity (DS_Copy)))
or else (Nkind (DS_Copy) = N_Attribute_Reference
and then Attribute_Name (DS_Copy) in
Name_Loop_Entry | Name_Old)
or else Has_Aspect (Etype (DS_Copy), Aspect_Iterable)
or else Nkind (DS_Copy) = N_Unchecked_Type_Conversion
or else (Nkind (DS_Copy) = N_Qualified_Expression
and then Is_Iterator (Etype (DS_Copy)))
then
-- This is an iterator specification. Rewrite it as such and
-- analyze it to capture function calls that may require
-- finalization actions.
declare
I_Spec : constant Node_Id :=
Make_Iterator_Specification (Sloc (N),
Defining_Identifier => Relocate_Node (Id),
Name => DS_Copy,
Subtype_Indication => Empty,
Reverse_Present => Reverse_Present (N));
Scheme : constant Node_Id := Parent (N);
begin
Set_Iterator_Specification (Scheme, I_Spec);
Set_Loop_Parameter_Specification (Scheme, Empty);
Set_Iterator_Filter (I_Spec,
Relocate_Node (Iterator_Filter (N)));
Analyze_Iterator_Specification (I_Spec);
-- In a generic context, analyze the original domain of
-- iteration, for name capture.
if not Expander_Active then
Analyze (DS);
end if;
-- Set kind of loop parameter, which may be used in the
-- subsequent analysis of the condition in a quantified
-- expression.
Mutate_Ekind (Id, E_Loop_Parameter);
return;
end;
-- Domain of iteration is not a function call, and is side-effect
-- free.
else
-- A quantified expression that appears in a pre/post condition
-- is preanalyzed several times. If the range is given by an
-- attribute reference it is rewritten as a range, and this is
-- done even with expansion disabled. If the type is already set
-- do not reanalyze, because a range with static bounds may be
-- typed Integer by default.
if Nkind (Parent (N)) = N_Quantified_Expression
and then Present (Etype (DS))
then
null;
else
Analyze (DS);
end if;
end if;
end if;
if DS = Error then
return;
end if;
-- Some additional checks if we are iterating through a type
if Is_Entity_Name (DS)
and then Present (Entity (DS))
and then Is_Type (Entity (DS))
then
-- The subtype indication may denote the completion of an incomplete
-- type declaration.
if Ekind (Entity (DS)) = E_Incomplete_Type then
Set_Entity (DS, Get_Full_View (Entity (DS)));
Set_Etype (DS, Entity (DS));
end if;
Check_Predicate_Use (Entity (DS));
end if;
-- Error if not discrete type
if not Is_Discrete_Type (Etype (DS)) then
Wrong_Type (DS, Any_Discrete);
Set_Etype (DS, Any_Type);
end if;
Check_Controlled_Array_Attribute (DS);
if Nkind (DS) = N_Subtype_Indication then
Check_Predicate_Use (Entity (Subtype_Mark (DS)));
end if;
if Nkind (DS) not in N_Raise_xxx_Error then
Make_Index (DS, N);
end if;
Mutate_Ekind (Id, E_Loop_Parameter);
-- A quantified expression which appears in a pre- or post-condition may
-- be analyzed multiple times. The analysis of the range creates several
-- itypes which reside in different scopes depending on whether the pre-
-- or post-condition has been expanded. Update the type of the loop
-- variable to reflect the proper itype at each stage of analysis.
-- Loop_Nod might not be present when we are preanalyzing a class-wide
-- pre/postcondition since preanalysis occurs in a place unrelated to
-- the actual code and the quantified expression may be the outermost
-- expression of the class-wide condition.
if No (Etype (Id))
or else Etype (Id) = Any_Type
or else
(Present (Etype (Id))
and then Is_Itype (Etype (Id))
and then Present (Loop_Nod)
and then Nkind (Parent (Loop_Nod)) = N_Expression_With_Actions
and then Nkind (Original_Node (Parent (Loop_Nod))) =
N_Quantified_Expression)
then
Set_Etype (Id, Etype (DS));
end if;
-- Treat a range as an implicit reference to the type, to inhibit
-- spurious warnings.
Generate_Reference (Base_Type (Etype (DS)), N, ' ');
Set_Is_Known_Valid (Id, True);
-- The loop is not a declarative part, so the loop variable must be
-- frozen explicitly. Do not freeze while preanalyzing a quantified
-- expression because the freeze node will not be inserted into the
-- tree due to flag Is_Spec_Expression being set.
if Nkind (Parent (N)) /= N_Quantified_Expression then
declare
Flist : constant List_Id := Freeze_Entity (Id, N);
begin
if Is_Non_Empty_List (Flist) then
Insert_Actions (N, Flist);
end if;
end;
end if;
-- Case where we have a range or a subtype, get type bounds
if Nkind (DS) in N_Range | N_Subtype_Indication
and then not Error_Posted (DS)
and then Etype (DS) /= Any_Type
and then Is_Discrete_Type (Etype (DS))
then
declare
L : Node_Id;
H : Node_Id;
Null_Range : Boolean := False;
begin
if Nkind (DS) = N_Range then
L := Low_Bound (DS);
H := High_Bound (DS);
else
L :=
Type_Low_Bound (Underlying_Type (Etype (Subtype_Mark (DS))));
H :=
Type_High_Bound (Underlying_Type (Etype (Subtype_Mark (DS))));
end if;
-- Check for null or possibly null range and issue warning. We
-- suppress such messages in generic templates and instances,
-- because in practice they tend to be dubious in these cases. The
-- check applies as well to rewritten array element loops where a
-- null range may be detected statically.
if Compile_Time_Compare (L, H, Assume_Valid => True) = GT then
if Compile_Time_Compare (L, H, Assume_Valid => False) = GT then
-- Since we know the range of the loop is always null,
-- set the appropriate flag to remove the loop entirely
-- during expansion.
Set_Is_Null_Loop (Loop_Nod);
Null_Range := True;
end if;
-- Suppress the warning if inside a generic template or
-- instance, since in practice they tend to be dubious in these
-- cases since they can result from intended parameterization.
if not Inside_A_Generic and then not In_Instance then
-- Specialize msg if invalid values could make the loop
-- non-null after all.
if Null_Range then
if Comes_From_Source (N) then
Error_Msg_N
("??loop range is null, loop will not execute", DS);
end if;
-- Here is where the loop could execute because of
-- invalid values, so issue appropriate message.
elsif Comes_From_Source (N) then
Error_Msg_N
("??loop range may be null, loop may not execute",
DS);
Error_Msg_N
("??can only execute if invalid values are present",
DS);
end if;
end if;
-- In either case, suppress warnings in the body of the loop,
-- since it is likely that these warnings will be inappropriate
-- if the loop never actually executes, which is likely.
Set_Suppress_Loop_Warnings (Loop_Nod);
-- The other case for a warning is a reverse loop where the
-- upper bound is the integer literal zero or one, and the
-- lower bound may exceed this value.
-- For example, we have
-- for J in reverse N .. 1 loop
-- In practice, this is very likely to be a case of reversing
-- the bounds incorrectly in the range.
elsif Reverse_Present (N)
and then Nkind (Original_Node (H)) = N_Integer_Literal
and then
(Intval (Original_Node (H)) = Uint_0
or else
Intval (Original_Node (H)) = Uint_1)
then
-- Lower bound may in fact be known and known not to exceed
-- upper bound (e.g. reverse 0 .. 1) and that's OK.
if Compile_Time_Known_Value (L)
and then Expr_Value (L) <= Expr_Value (H)
then
null;
-- Otherwise warning is warranted
else
Error_Msg_N ("??loop range may be null", DS);
Error_Msg_N ("\??bounds may be wrong way round", DS);
end if;
end if;
-- Check if either bound is known to be outside the range of the
-- loop parameter type, this is e.g. the case of a loop from
-- 20..X where the type is 1..19.
-- Such a loop is dubious since either it raises CE or it executes
-- zero times, and that cannot be useful!
if Etype (DS) /= Any_Type
and then not Error_Posted (DS)
and then Nkind (DS) = N_Subtype_Indication
and then Nkind (Constraint (DS)) = N_Range_Constraint
then
declare
LLo : constant Node_Id :=
Low_Bound (Range_Expression (Constraint (DS)));
LHi : constant Node_Id :=
High_Bound (Range_Expression (Constraint (DS)));
Bad_Bound : Node_Id := Empty;
-- Suspicious loop bound
begin
-- At this stage L, H are the bounds of the type, and LLo
-- Lhi are the low bound and high bound of the loop.
if Compile_Time_Compare (LLo, L, Assume_Valid => True) = LT
or else
Compile_Time_Compare (LLo, H, Assume_Valid => True) = GT
then
Bad_Bound := LLo;
end if;
if Compile_Time_Compare (LHi, L, Assume_Valid => True) = LT
or else
Compile_Time_Compare (LHi, H, Assume_Valid => True) = GT
then
Bad_Bound := LHi;
end if;
if Present (Bad_Bound) then
Error_Msg_N
("suspicious loop bound out of range of "
& "loop subtype??", Bad_Bound);
Error_Msg_N
("\loop executes zero times or raises "
& "Constraint_Error??", Bad_Bound);
end if;
if Compile_Time_Compare (LLo, LHi, Assume_Valid => False)
= GT
then
Error_Msg_N ("??constrained range is null",
Constraint (DS));
-- Additional constraints on modular types can be
-- confusing, add more information.
if Ekind (Etype (DS)) = E_Modular_Integer_Subtype then
Error_Msg_Uint_1 := Intval (LLo);
Error_Msg_Uint_2 := Intval (LHi);
Error_Msg_NE ("\iterator has modular type &, " &
"so the loop has bounds ^ ..^",
Constraint (DS),
Subtype_Mark (DS));
end if;
Set_Is_Null_Loop (Loop_Nod);
Null_Range := True;
-- Suppress other warnigns about the body of the loop, as
-- it will never execute.
Set_Suppress_Loop_Warnings (Loop_Nod);
end if;
end;
end if;
-- This declare block is about warnings, if we get an exception while
-- testing for warnings, we simply abandon the attempt silently. This
-- most likely occurs as the result of a previous error, but might
-- just be an obscure case we have missed. In either case, not giving
-- the warning is perfectly acceptable.
exception
when others =>
-- With debug flag K we will get an exception unless an error
-- has already occurred (useful for debugging).
if Debug_Flag_K then
Check_Error_Detected;
end if;
end;
end if;
if Present (Iterator_Filter (N)) then
Analyze_And_Resolve (Iterator_Filter (N), Standard_Boolean);
end if;
-- A loop parameter cannot be effectively volatile (SPARK RM 7.1.3(4)).
-- This check is relevant only when SPARK_Mode is on as it is not a
-- standard Ada legality check.
if SPARK_Mode = On and then Is_Effectively_Volatile (Id) then
Error_Msg_N ("loop parameter cannot be volatile", Id);
end if;
end Analyze_Loop_Parameter_Specification;
----------------------------
-- Analyze_Loop_Statement --
----------------------------
procedure Analyze_Loop_Statement (N : Node_Id) is
-- The following exception is raised by routine Prepare_Loop_Statement
-- to avoid further analysis of a transformed loop.
procedure Prepare_Loop_Statement
(Iter : Node_Id;
Stop_Processing : out Boolean);
-- Determine whether loop statement N with iteration scheme Iter must be
-- transformed prior to analysis, and if so, perform it.
-- If Stop_Processing is set to True, should stop further processing.
----------------------------
-- Prepare_Loop_Statement --
----------------------------
procedure Prepare_Loop_Statement
(Iter : Node_Id;
Stop_Processing : out Boolean)
is
function Has_Sec_Stack_Default_Iterator
(Cont_Typ : Entity_Id) return Boolean;
pragma Inline (Has_Sec_Stack_Default_Iterator);
-- Determine whether container type Cont_Typ has a default iterator
-- that requires secondary stack management.
function Is_Sec_Stack_Iteration_Primitive
(Cont_Typ : Entity_Id;
Iter_Prim_Nam : Name_Id) return Boolean;
pragma Inline (Is_Sec_Stack_Iteration_Primitive);
-- Determine whether container type Cont_Typ has an iteration routine
-- described by its name Iter_Prim_Nam that requires secondary stack
-- management.
function Is_Wrapped_In_Block (Stmt : Node_Id) return Boolean;
pragma Inline (Is_Wrapped_In_Block);
-- Determine whether arbitrary statement Stmt is the sole statement
-- wrapped within some block, excluding pragmas.
procedure Prepare_Iterator_Loop
(Iter_Spec : Node_Id;
Stop_Processing : out Boolean);
pragma Inline (Prepare_Iterator_Loop);
-- Prepare an iterator loop with iteration specification Iter_Spec
-- for transformation if needed.
-- If Stop_Processing is set to True, should stop further processing.
procedure Prepare_Param_Spec_Loop
(Param_Spec : Node_Id;
Stop_Processing : out Boolean);
pragma Inline (Prepare_Param_Spec_Loop);
-- Prepare a discrete loop with parameter specification Param_Spec
-- for transformation if needed.
-- If Stop_Processing is set to True, should stop further processing.
procedure Wrap_Loop_Statement (Manage_Sec_Stack : Boolean);
pragma Inline (Wrap_Loop_Statement);
-- Wrap loop statement N within a block. Flag Manage_Sec_Stack must
-- be set when the block must mark and release the secondary stack.
-- Should stop further processing after calling this procedure.
------------------------------------
-- Has_Sec_Stack_Default_Iterator --
------------------------------------
function Has_Sec_Stack_Default_Iterator
(Cont_Typ : Entity_Id) return Boolean
is
Def_Iter : constant Node_Id :=
Find_Value_Of_Aspect
(Cont_Typ, Aspect_Default_Iterator);
begin
return
Present (Def_Iter)
and then Requires_Transient_Scope (Etype (Def_Iter));
end Has_Sec_Stack_Default_Iterator;
--------------------------------------
-- Is_Sec_Stack_Iteration_Primitive --
--------------------------------------
function Is_Sec_Stack_Iteration_Primitive
(Cont_Typ : Entity_Id;
Iter_Prim_Nam : Name_Id) return Boolean
is
Iter_Prim : constant Entity_Id :=