2364 lines
81 KiB
Ada
2364 lines
81 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S E M _ C H 5 --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 1992-2006, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
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-- Boston, MA 02110-1301, USA. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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with Atree; use Atree;
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with Checks; use Checks;
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with Debug; use Debug;
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with Einfo; use Einfo;
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with Errout; use Errout;
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with Expander; use Expander;
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with Exp_Util; use Exp_Util;
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with Freeze; use Freeze;
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with Lib; use Lib;
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with Lib.Xref; use Lib.Xref;
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with Nlists; use Nlists;
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with Nmake; use Nmake;
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with Opt; use Opt;
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with Rtsfind; use Rtsfind;
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with Sem; use Sem;
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with Sem_Case; use Sem_Case;
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with Sem_Ch3; use Sem_Ch3;
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with Sem_Ch8; use Sem_Ch8;
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with Sem_Disp; use Sem_Disp;
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with Sem_Elab; use Sem_Elab;
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with Sem_Eval; use Sem_Eval;
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with Sem_Res; use Sem_Res;
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with Sem_Type; use Sem_Type;
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with Sem_Util; use Sem_Util;
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with Sem_Warn; use Sem_Warn;
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with Snames; use Snames;
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with Stand; use Stand;
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with Sinfo; use Sinfo;
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with Targparm; use Targparm;
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with Tbuild; use Tbuild;
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with Uintp; use Uintp;
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package body Sem_Ch5 is
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Unblocked_Exit_Count : Nat := 0;
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-- This variable is used when processing if statements, case statements,
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-- and block statements. It counts the number of exit points that are
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-- not blocked by unconditional transfer instructions: for IF and CASE,
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-- these are the branches of the conditional; for a block, they are the
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-- statement sequence of the block, and the statement sequences of any
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-- exception handlers that are part of the block. When processing is
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-- complete, if this count is zero, it means that control cannot fall
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-- through the IF, CASE or block statement. This is used for the
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-- generation of warning messages. This variable is recursively saved
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-- on entry to processing the construct, and restored on exit.
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-----------------------
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-- Local Subprograms --
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-----------------------
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procedure Analyze_Iteration_Scheme (N : Node_Id);
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------------------------
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-- Analyze_Assignment --
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------------------------
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procedure Analyze_Assignment (N : Node_Id) is
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Lhs : constant Node_Id := Name (N);
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Rhs : constant Node_Id := Expression (N);
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T1 : Entity_Id;
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T2 : Entity_Id;
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Decl : Node_Id;
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procedure Diagnose_Non_Variable_Lhs (N : Node_Id);
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-- N is the node for the left hand side of an assignment, and it
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-- is not a variable. This routine issues an appropriate diagnostic.
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procedure Kill_Lhs;
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-- This is called to kill current value settings of a simple variable
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-- on the left hand side. We call it if we find any error in analyzing
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-- the assignment, and at the end of processing before setting any new
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-- current values in place.
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procedure Set_Assignment_Type
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(Opnd : Node_Id;
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Opnd_Type : in out Entity_Id);
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-- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type
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-- is the nominal subtype. This procedure is used to deal with cases
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-- where the nominal subtype must be replaced by the actual subtype.
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-------------------------------
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-- Diagnose_Non_Variable_Lhs --
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-------------------------------
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procedure Diagnose_Non_Variable_Lhs (N : Node_Id) is
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begin
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-- Not worth posting another error if left hand side already
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-- flagged as being illegal in some respect
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if Error_Posted (N) then
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return;
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-- Some special bad cases of entity names
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elsif Is_Entity_Name (N) then
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if Ekind (Entity (N)) = E_In_Parameter then
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Error_Msg_N
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("assignment to IN mode parameter not allowed", N);
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-- Private declarations in a protected object are turned into
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-- constants when compiling a protected function.
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elsif Present (Scope (Entity (N)))
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and then Is_Protected_Type (Scope (Entity (N)))
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and then
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(Ekind (Current_Scope) = E_Function
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or else
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Ekind (Enclosing_Dynamic_Scope (Current_Scope)) = E_Function)
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then
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Error_Msg_N
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("protected function cannot modify protected object", N);
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elsif Ekind (Entity (N)) = E_Loop_Parameter then
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Error_Msg_N
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("assignment to loop parameter not allowed", N);
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else
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Error_Msg_N
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("left hand side of assignment must be a variable", N);
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end if;
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-- For indexed components or selected components, test prefix
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elsif Nkind (N) = N_Indexed_Component then
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Diagnose_Non_Variable_Lhs (Prefix (N));
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-- Another special case for assignment to discriminant
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elsif Nkind (N) = N_Selected_Component then
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if Present (Entity (Selector_Name (N)))
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and then Ekind (Entity (Selector_Name (N))) = E_Discriminant
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then
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Error_Msg_N
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("assignment to discriminant not allowed", N);
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else
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Diagnose_Non_Variable_Lhs (Prefix (N));
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end if;
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else
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-- If we fall through, we have no special message to issue!
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Error_Msg_N ("left hand side of assignment must be a variable", N);
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end if;
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end Diagnose_Non_Variable_Lhs;
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--------------
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-- Kill_LHS --
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--------------
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procedure Kill_Lhs is
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begin
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if Is_Entity_Name (Lhs) then
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declare
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Ent : constant Entity_Id := Entity (Lhs);
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begin
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if Present (Ent) then
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Kill_Current_Values (Ent);
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end if;
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end;
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end if;
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end Kill_Lhs;
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-------------------------
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-- Set_Assignment_Type --
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-------------------------
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procedure Set_Assignment_Type
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(Opnd : Node_Id;
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Opnd_Type : in out Entity_Id)
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is
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begin
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Require_Entity (Opnd);
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-- If the assignment operand is an in-out or out parameter, then we
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-- get the actual subtype (needed for the unconstrained case).
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-- If the operand is the actual in an entry declaration, then within
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-- the accept statement it is replaced with a local renaming, which
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-- may also have an actual subtype.
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if Is_Entity_Name (Opnd)
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and then (Ekind (Entity (Opnd)) = E_Out_Parameter
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or else Ekind (Entity (Opnd)) =
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E_In_Out_Parameter
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or else Ekind (Entity (Opnd)) =
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E_Generic_In_Out_Parameter
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or else
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(Ekind (Entity (Opnd)) = E_Variable
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and then Nkind (Parent (Entity (Opnd))) =
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N_Object_Renaming_Declaration
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and then Nkind (Parent (Parent (Entity (Opnd)))) =
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N_Accept_Statement))
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then
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Opnd_Type := Get_Actual_Subtype (Opnd);
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-- If assignment operand is a component reference, then we get the
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-- actual subtype of the component for the unconstrained case.
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elsif
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(Nkind (Opnd) = N_Selected_Component
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or else Nkind (Opnd) = N_Explicit_Dereference)
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and then not Is_Unchecked_Union (Opnd_Type)
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then
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Decl := Build_Actual_Subtype_Of_Component (Opnd_Type, Opnd);
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if Present (Decl) then
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Insert_Action (N, Decl);
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Mark_Rewrite_Insertion (Decl);
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Analyze (Decl);
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Opnd_Type := Defining_Identifier (Decl);
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Set_Etype (Opnd, Opnd_Type);
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Freeze_Itype (Opnd_Type, N);
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elsif Is_Constrained (Etype (Opnd)) then
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Opnd_Type := Etype (Opnd);
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end if;
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-- For slice, use the constrained subtype created for the slice
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elsif Nkind (Opnd) = N_Slice then
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Opnd_Type := Etype (Opnd);
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end if;
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end Set_Assignment_Type;
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-- Start of processing for Analyze_Assignment
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begin
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Analyze (Rhs);
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Analyze (Lhs);
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-- Start type analysis for assignment
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T1 := Etype (Lhs);
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-- In the most general case, both Lhs and Rhs can be overloaded, and we
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-- must compute the intersection of the possible types on each side.
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if Is_Overloaded (Lhs) then
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declare
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I : Interp_Index;
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It : Interp;
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begin
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T1 := Any_Type;
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Get_First_Interp (Lhs, I, It);
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while Present (It.Typ) loop
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if Has_Compatible_Type (Rhs, It.Typ) then
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if T1 /= Any_Type then
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-- An explicit dereference is overloaded if the prefix
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-- is. Try to remove the ambiguity on the prefix, the
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-- error will be posted there if the ambiguity is real.
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if Nkind (Lhs) = N_Explicit_Dereference then
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declare
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PI : Interp_Index;
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PI1 : Interp_Index := 0;
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PIt : Interp;
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Found : Boolean;
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begin
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Found := False;
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Get_First_Interp (Prefix (Lhs), PI, PIt);
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while Present (PIt.Typ) loop
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if Is_Access_Type (PIt.Typ)
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and then Has_Compatible_Type
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(Rhs, Designated_Type (PIt.Typ))
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then
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if Found then
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PIt :=
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Disambiguate (Prefix (Lhs),
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PI1, PI, Any_Type);
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if PIt = No_Interp then
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Error_Msg_N
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("ambiguous left-hand side"
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& " in assignment", Lhs);
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exit;
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else
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Resolve (Prefix (Lhs), PIt.Typ);
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end if;
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exit;
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else
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Found := True;
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PI1 := PI;
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end if;
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end if;
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Get_Next_Interp (PI, PIt);
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end loop;
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end;
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else
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Error_Msg_N
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("ambiguous left-hand side in assignment", Lhs);
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exit;
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end if;
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else
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T1 := It.Typ;
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end if;
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end if;
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Get_Next_Interp (I, It);
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end loop;
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end;
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if T1 = Any_Type then
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Error_Msg_N
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("no valid types for left-hand side for assignment", Lhs);
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Kill_Lhs;
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return;
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end if;
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end if;
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Resolve (Lhs, T1);
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if not Is_Variable (Lhs) then
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-- Ada 2005 (AI-327): Check assignment to the attribute Priority of
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-- a protected object.
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declare
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Ent : Entity_Id;
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S : Entity_Id;
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begin
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if Ada_Version >= Ada_05 then
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-- Handle chains of renamings
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Ent := Lhs;
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while Nkind (Ent) in N_Has_Entity
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and then Present (Entity (Ent))
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and then Present (Renamed_Object (Entity (Ent)))
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loop
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Ent := Renamed_Object (Entity (Ent));
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end loop;
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if (Nkind (Ent) = N_Attribute_Reference
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and then Attribute_Name (Ent) = Name_Priority)
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-- Renamings of the attribute Priority applied to protected
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-- objects have been previously expanded into calls to the
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-- Get_Ceiling run-time subprogram.
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or else
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(Nkind (Ent) = N_Function_Call
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and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
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or else
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Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)))
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then
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-- The enclosing subprogram cannot be a protected function
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S := Current_Scope;
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while not (Is_Subprogram (S)
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and then Convention (S) = Convention_Protected)
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and then S /= Standard_Standard
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loop
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S := Scope (S);
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end loop;
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if Ekind (S) = E_Function
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and then Convention (S) = Convention_Protected
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then
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Error_Msg_N
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("protected function cannot modify protected object",
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Lhs);
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end if;
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-- Changes of the ceiling priority of the protected object
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-- are only effective if the Ceiling_Locking policy is in
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-- effect (AARM D.5.2 (5/2)).
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if Locking_Policy /= 'C' then
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Error_Msg_N ("assignment to the attribute PRIORITY has " &
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"no effect?", Lhs);
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Error_Msg_N ("\since no Locking_Policy has been " &
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"specified", Lhs);
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end if;
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return;
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end if;
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end if;
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end;
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Diagnose_Non_Variable_Lhs (Lhs);
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return;
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elsif Is_Limited_Type (T1)
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and then not Assignment_OK (Lhs)
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and then not Assignment_OK (Original_Node (Lhs))
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then
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Error_Msg_N
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("left hand of assignment must not be limited type", Lhs);
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Explain_Limited_Type (T1, Lhs);
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return;
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end if;
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-- Resolution may have updated the subtype, in case the left-hand
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-- side is a private protected component. Use the correct subtype
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-- to avoid scoping issues in the back-end.
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T1 := Etype (Lhs);
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-- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
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-- type. For example:
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-- limited with P;
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-- package Pkg is
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-- type Acc is access P.T;
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-- end Pkg;
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-- with Pkg; use Acc;
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-- procedure Example is
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-- A, B : Acc;
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-- begin
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-- A.all := B.all; -- ERROR
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-- end Example;
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if Nkind (Lhs) = N_Explicit_Dereference
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and then Ekind (T1) = E_Incomplete_Type
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then
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Error_Msg_N ("invalid use of incomplete type", Lhs);
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Kill_Lhs;
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return;
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end if;
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Set_Assignment_Type (Lhs, T1);
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Resolve (Rhs, T1);
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Check_Unset_Reference (Rhs);
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-- Remaining steps are skipped if Rhs was syntactically in error
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if Rhs = Error then
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Kill_Lhs;
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return;
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end if;
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T2 := Etype (Rhs);
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if not Covers (T1, T2) then
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Wrong_Type (Rhs, Etype (Lhs));
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Kill_Lhs;
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return;
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end if;
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-- Ada 2005 (AI-326): In case of explicit dereference of incomplete
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-- types, use the non-limited view if available
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if Nkind (Rhs) = N_Explicit_Dereference
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and then Ekind (T2) = E_Incomplete_Type
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and then Is_Tagged_Type (T2)
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and then Present (Non_Limited_View (T2))
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then
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T2 := Non_Limited_View (T2);
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end if;
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Set_Assignment_Type (Rhs, T2);
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if Total_Errors_Detected /= 0 then
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if No (T1) then
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T1 := Any_Type;
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end if;
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if No (T2) then
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T2 := Any_Type;
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end if;
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end if;
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if T1 = Any_Type or else T2 = Any_Type then
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Kill_Lhs;
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return;
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end if;
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if (Is_Class_Wide_Type (T2) or else Is_Dynamically_Tagged (Rhs))
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and then not Is_Class_Wide_Type (T1)
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then
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Error_Msg_N ("dynamically tagged expression not allowed!", Rhs);
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elsif Is_Class_Wide_Type (T1)
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and then not Is_Class_Wide_Type (T2)
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and then not Is_Tag_Indeterminate (Rhs)
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and then not Is_Dynamically_Tagged (Rhs)
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then
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Error_Msg_N ("dynamically tagged expression required!", Rhs);
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end if;
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|
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-- Propagate the tag from a class-wide target to the rhs when the rhs
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-- is a tag-indeterminate call.
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if Is_Tag_Indeterminate (Rhs) then
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if Is_Class_Wide_Type (T1) then
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Propagate_Tag (Lhs, Rhs);
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elsif Nkind (Rhs) = N_Function_Call
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and then Is_Entity_Name (Name (Rhs))
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and then Is_Abstract_Subprogram (Entity (Name (Rhs)))
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then
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Error_Msg_N
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("call to abstract function must be dispatching", Name (Rhs));
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elsif Nkind (Rhs) = N_Qualified_Expression
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and then Nkind (Expression (Rhs)) = N_Function_Call
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and then Is_Entity_Name (Name (Expression (Rhs)))
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and then
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Is_Abstract_Subprogram (Entity (Name (Expression (Rhs))))
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then
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Error_Msg_N
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("call to abstract function must be dispatching",
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Name (Expression (Rhs)));
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end if;
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end if;
|
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|
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-- Ada 2005 (AI-230 and 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.
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|
|
if Ada_Version >= Ada_05
|
|
and then Ekind (T1) = E_Anonymous_Access_Type
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then
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Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
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Analyze_And_Resolve (Rhs, T1);
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end if;
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|
|
-- Ada 2005 (AI-231)
|
|
|
|
if Ada_Version >= Ada_05
|
|
and then Can_Never_Be_Null (T1)
|
|
and then not Assignment_OK (Lhs)
|
|
then
|
|
if Nkind (Rhs) = N_Null then
|
|
Apply_Compile_Time_Constraint_Error
|
|
(N => Rhs,
|
|
Msg => "(Ada 2005) NULL not allowed in null-excluding objects?",
|
|
Reason => CE_Null_Not_Allowed);
|
|
return;
|
|
|
|
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
|
|
Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
|
|
|
|
-- For array types, verify that lengths match. If the right hand side
|
|
-- if 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 Lsh and Rhs are equal,
|
|
-- but of course the indices 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 (Rhs, Etype (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);
|
|
|
|
-- ??? 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 entity is the same on both sides
|
|
|
|
and then Is_Entity_Name (Lhs)
|
|
and then Is_Entity_Name (Original_Node (Rhs))
|
|
and then Entity (Lhs) = Entity (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
|
|
Error_Msg_NE
|
|
("?useless assignment of & to itself", N, Entity (Lhs));
|
|
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) > 64)
|
|
then
|
|
Error_Msg_CRT ("composite assignment", N);
|
|
end if;
|
|
|
|
-- Check elaboration warning for left side if not in elab code
|
|
|
|
if not In_Subprogram_Or_Concurrent_Unit then
|
|
Check_Elab_Assign (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) and 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.
|
|
|
|
if Warn_On_Modified_Unread
|
|
and then Ekind (Ent) = E_Variable
|
|
and then Comes_From_Source (N)
|
|
and then In_Extended_Main_Source_Unit (Ent)
|
|
then
|
|
Warn_On_Useless_Assignment (Ent, Sloc (N));
|
|
Set_Last_Assignment (Ent, Lhs);
|
|
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;
|
|
end Analyze_Assignment;
|
|
|
|
-----------------------------
|
|
-- Analyze_Block_Statement --
|
|
-----------------------------
|
|
|
|
procedure Analyze_Block_Statement (N : Node_Id) is
|
|
Decls : constant List_Id := Declarations (N);
|
|
Id : constant Node_Id := Identifier (N);
|
|
HSS : constant Node_Id := Handled_Statement_Sequence (N);
|
|
|
|
begin
|
|
-- If no handled statement sequence is present, things are really
|
|
-- messed up, and we just return immediately (this is a defence
|
|
-- against previous errors).
|
|
|
|
if No (HSS) then
|
|
return;
|
|
end if;
|
|
|
|
-- 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 excption 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 we have previous errors, then
|
|
-- just remove the identifier and continue, otherwise raise
|
|
-- an exception.
|
|
|
|
if No (Ent) then
|
|
if Total_Errors_Detected /= 0 then
|
|
Set_Identifier (N, Empty);
|
|
else
|
|
raise Program_Error;
|
|
end if;
|
|
|
|
else
|
|
Set_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));
|
|
New_Scope (Ent);
|
|
|
|
if Present (Decls) then
|
|
Analyze_Declarations (Decls);
|
|
Check_Completion;
|
|
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);
|
|
Warn_On_Useless_Assignments (Ent);
|
|
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_Case_Statement --
|
|
----------------------------
|
|
|
|
procedure Analyze_Case_Statement (N : Node_Id) is
|
|
Exp : Node_Id;
|
|
Exp_Type : Entity_Id;
|
|
Exp_Btype : Entity_Id;
|
|
Last_Choice : Nat;
|
|
Dont_Care : Boolean;
|
|
Others_Present : Boolean;
|
|
|
|
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.
|
|
|
|
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
|
|
-- Recursively save value of this global, will be restored on exit
|
|
|
|
procedure Non_Static_Choice_Error (Choice : Node_Id);
|
|
-- Error routine invoked by the generic instantiation below when
|
|
-- the case statment has a non static choice.
|
|
|
|
procedure Process_Statements (Alternative : Node_Id);
|
|
-- Analyzes all the statements associated to a case alternative.
|
|
-- Needed by the generic instantiation below.
|
|
|
|
package Case_Choices_Processing is new
|
|
Generic_Choices_Processing
|
|
(Get_Alternatives => Alternatives,
|
|
Get_Choices => Discrete_Choices,
|
|
Process_Empty_Choice => No_OP,
|
|
Process_Non_Static_Choice => Non_Static_Choice_Error,
|
|
Process_Associated_Node => Process_Statements);
|
|
use Case_Choices_Processing;
|
|
-- 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
|
|
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 Ekind (Ent) = E_Variable
|
|
or else
|
|
Ekind (Ent) = E_In_Out_Parameter
|
|
or else
|
|
Ekind (Ent) = E_Out_Parameter
|
|
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 a variable
|
|
|
|
Analyze_Statements (Statements (Alternative));
|
|
end Process_Statements;
|
|
|
|
-- Table to record choices. Put after subprograms since we make
|
|
-- a call to Number_Of_Choices to get the right number of entries.
|
|
|
|
Case_Table : Choice_Table_Type (1 .. Number_Of_Choices (N));
|
|
|
|
-- Start of processing for Analyze_Case_Statement
|
|
|
|
begin
|
|
Unblocked_Exit_Count := 0;
|
|
Exp := Expression (N);
|
|
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, Etype (Exp));
|
|
Exp_Type := Full_View (Etype (Exp));
|
|
|
|
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;
|
|
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 Analyze_Choices which does the rest of the work
|
|
|
|
Analyze_Choices
|
|
(N, Exp_Type, Case_Table, Last_Choice, Dont_Care, Others_Present);
|
|
|
|
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 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.
|
|
|
|
procedure Analyze_Exit_Statement (N : Node_Id) is
|
|
Target : constant Node_Id := Name (N);
|
|
Cond : constant Node_Id := Condition (N);
|
|
Scope_Id : Entity_Id;
|
|
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);
|
|
exit;
|
|
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;
|
|
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
|
|
Check_Unreachable_Code (N);
|
|
|
|
Analyze (Label);
|
|
Label_Ent := Entity (Label);
|
|
|
|
-- Ignore previous error
|
|
|
|
if Label_Ent = Any_Id then
|
|
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) /= E_Block
|
|
and then Ekind (Scope_Id) /= E_Loop
|
|
and then Ekind (Scope_Id) /= 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_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
|
|
E : Node_Id;
|
|
|
|
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;
|
|
|
|
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 -- 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;
|
|
|
|
-- Start of 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;
|
|
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 as well as
|
|
-- 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);
|
|
Set_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
|
|
|
|
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 pre-analyze a copy of
|
|
-- the range in order to determine the expected type, and analyze and
|
|
-- resolve the original bounds.
|
|
|
|
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.
|
|
|
|
--------------------
|
|
-- Process_Bounds --
|
|
--------------------
|
|
|
|
procedure Process_Bounds (R : Node_Id) is
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
R_Copy : constant Node_Id := New_Copy_Tree (R);
|
|
Lo : constant Node_Id := Low_Bound (R);
|
|
Hi : constant Node_Id := High_Bound (R);
|
|
New_Lo_Bound : Node_Id := Empty;
|
|
New_Hi_Bound : Node_Id := Empty;
|
|
Typ : Entity_Id;
|
|
Save_Analysis : Boolean;
|
|
|
|
function One_Bound
|
|
(Original_Bound : Node_Id;
|
|
Analyzed_Bound : Node_Id) return Node_Id;
|
|
-- Create one declaration followed by one assignment statement
|
|
-- to capture the value of bound. We create a separate assignment
|
|
-- in order to force the creation of a block in case the bound
|
|
-- contains a call that uses the secondary stack.
|
|
|
|
---------------
|
|
-- One_Bound --
|
|
---------------
|
|
|
|
function One_Bound
|
|
(Original_Bound : Node_Id;
|
|
Analyzed_Bound : Node_Id) return Node_Id
|
|
is
|
|
Assign : Node_Id;
|
|
Id : Entity_Id;
|
|
Decl : Node_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) = N_Integer_Literal
|
|
or else Is_Entity_Name (Analyzed_Bound)
|
|
then
|
|
Analyze_And_Resolve (Original_Bound, Typ);
|
|
return Original_Bound;
|
|
|
|
else
|
|
Analyze_And_Resolve (Original_Bound, Typ);
|
|
end if;
|
|
|
|
Id :=
|
|
Make_Defining_Identifier (Loc,
|
|
Chars => New_Internal_Name ('S'));
|
|
|
|
Decl :=
|
|
Make_Object_Declaration (Loc,
|
|
Defining_Identifier => Id,
|
|
Object_Definition => New_Occurrence_Of (Typ, Loc));
|
|
|
|
Insert_Before (Parent (N), Decl);
|
|
Analyze (Decl);
|
|
|
|
Assign :=
|
|
Make_Assignment_Statement (Loc,
|
|
Name => New_Occurrence_Of (Id, Loc),
|
|
Expression => Relocate_Node (Original_Bound));
|
|
|
|
Insert_Before (Parent (N), Assign);
|
|
Analyze (Assign);
|
|
|
|
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;
|
|
|
|
-- Start of processing for Process_Bounds
|
|
|
|
begin
|
|
-- Determine expected type of range by analyzing separate copy
|
|
-- Do the analysis and resolution of the copy of the bounds with
|
|
-- expansion disabled, to prevent the generation of finalization
|
|
-- actions on each bound. This prevents memory leaks when the
|
|
-- bounds contain calls to functions returning controlled arrays.
|
|
|
|
Set_Parent (R_Copy, Parent (R));
|
|
Save_Analysis := Full_Analysis;
|
|
Full_Analysis := False;
|
|
Expander_Mode_Save_And_Set (False);
|
|
|
|
Analyze (R_Copy);
|
|
|
|
if Is_Overloaded (R_Copy) then
|
|
|
|
-- Apply preference rules for range of predefined integer types,
|
|
-- or diagnose true ambiguity.
|
|
|
|
declare
|
|
I : Interp_Index;
|
|
It : Interp;
|
|
Found : Entity_Id := Empty;
|
|
|
|
begin
|
|
Get_First_Interp (R_Copy, I, It);
|
|
while Present (It.Typ) loop
|
|
if Is_Discrete_Type (It.Typ) then
|
|
if No (Found) then
|
|
Found := It.Typ;
|
|
else
|
|
if Scope (Found) = Standard_Standard then
|
|
null;
|
|
|
|
elsif Scope (It.Typ) = Standard_Standard then
|
|
Found := It.Typ;
|
|
|
|
else
|
|
-- Both of them are user-defined
|
|
|
|
Error_Msg_N
|
|
("ambiguous bounds in range of iteration",
|
|
R_Copy);
|
|
Error_Msg_N ("\possible interpretations:", R_Copy);
|
|
Error_Msg_NE ("\\} ", R_Copy, Found);
|
|
Error_Msg_NE ("\\} ", R_Copy, It.Typ);
|
|
exit;
|
|
end if;
|
|
end if;
|
|
end if;
|
|
|
|
Get_Next_Interp (I, It);
|
|
end loop;
|
|
end;
|
|
end if;
|
|
|
|
Resolve (R_Copy);
|
|
Expander_Mode_Restore;
|
|
Full_Analysis := Save_Analysis;
|
|
|
|
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 that carry 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_Bound := One_Bound (Lo, Low_Bound (R_Copy));
|
|
New_Hi_Bound := One_Bound (Hi, High_Bound (R_Copy));
|
|
|
|
-- Propagate staticness to loop range itself, in case the
|
|
-- corresponding subtype is static.
|
|
|
|
if New_Lo_Bound /= Lo
|
|
and then Is_Static_Expression (New_Lo_Bound)
|
|
then
|
|
Rewrite (Low_Bound (R), New_Copy (New_Lo_Bound));
|
|
end if;
|
|
|
|
if New_Hi_Bound /= Hi
|
|
and then Is_Static_Expression (New_Hi_Bound)
|
|
then
|
|
Rewrite (High_Bound (R), New_Copy (New_Hi_Bound));
|
|
end if;
|
|
end Process_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_Defining_Identifier
|
|
(Loc, New_Internal_Name ('S'));
|
|
Decl : Node_Id;
|
|
|
|
begin
|
|
Decl :=
|
|
Make_Subtype_Declaration (Loc,
|
|
Defining_Identifier => Subt,
|
|
Subtype_Indication =>
|
|
Make_Subtype_Indication (Loc,
|
|
Subtype_Mark => New_Reference_To (Indx, Loc),
|
|
Constraint =>
|
|
Make_Range_Constraint (Loc,
|
|
Relocate_Node (DS))));
|
|
Insert_Before (Parent (N), Decl);
|
|
Analyze (Decl);
|
|
|
|
Rewrite (DS,
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix => New_Reference_To (Subt, Loc),
|
|
Attribute_Name => Attribute_Name (DS)));
|
|
Analyze (DS);
|
|
end;
|
|
end if;
|
|
end Check_Controlled_Array_Attribute;
|
|
|
|
-- Start of processing for Analyze_Iteration_Scheme
|
|
|
|
begin
|
|
-- For an infinite loop, there is no iteration scheme
|
|
|
|
if No (N) then
|
|
return;
|
|
|
|
else
|
|
declare
|
|
Cond : constant Node_Id := Condition (N);
|
|
|
|
begin
|
|
-- For WHILE loop, verify that the condition is a Boolean
|
|
-- expression and resolve and check it.
|
|
|
|
if Present (Cond) then
|
|
Analyze_And_Resolve (Cond, Any_Boolean);
|
|
Check_Unset_Reference (Cond);
|
|
Set_Current_Value_Condition (N);
|
|
return;
|
|
|
|
-- Else we have a FOR loop
|
|
|
|
else
|
|
declare
|
|
LP : constant Node_Id := Loop_Parameter_Specification (N);
|
|
Id : constant Entity_Id := Defining_Identifier (LP);
|
|
DS : constant Node_Id := Discrete_Subtype_Definition (LP);
|
|
|
|
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 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 Enclosing_Dynamic_Scope (H) =
|
|
Enclosing_Dynamic_Scope (Id)
|
|
and then Ekind (H) = E_Variable
|
|
and then Is_Discrete_Type (Etype (H))
|
|
then
|
|
Set_Hiding_Loop_Variable (H, Id);
|
|
end if;
|
|
end;
|
|
|
|
-- Now analyze the subtype definition. If it is
|
|
-- a range, create temporaries for bounds.
|
|
|
|
if Nkind (DS) = N_Range
|
|
and then Expander_Active
|
|
then
|
|
Process_Bounds (DS);
|
|
else
|
|
Analyze (DS);
|
|
end if;
|
|
|
|
if DS = Error then
|
|
return;
|
|
end if;
|
|
|
|
-- The subtype indication may denote the completion
|
|
-- of an incomplete type declaration.
|
|
|
|
if Is_Entity_Name (DS)
|
|
and then Present (Entity (DS))
|
|
and then Is_Type (Entity (DS))
|
|
and then Ekind (Entity (DS)) = E_Incomplete_Type
|
|
then
|
|
Set_Entity (DS, Get_Full_View (Entity (DS)));
|
|
Set_Etype (DS, Entity (DS));
|
|
end if;
|
|
|
|
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);
|
|
|
|
Make_Index (DS, LP);
|
|
|
|
Set_Ekind (Id, E_Loop_Parameter);
|
|
Set_Etype (Id, Etype (DS));
|
|
Set_Is_Known_Valid (Id, True);
|
|
|
|
-- The loop is not a declarative part, so the only entity
|
|
-- declared "within" must be frozen explicitly.
|
|
|
|
declare
|
|
Flist : constant List_Id := Freeze_Entity (Id, Sloc (N));
|
|
begin
|
|
if Is_Non_Empty_List (Flist) then
|
|
Insert_Actions (N, Flist);
|
|
end if;
|
|
end;
|
|
|
|
-- 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.
|
|
|
|
if Nkind (DS) = N_Range
|
|
and then Comes_From_Source (N)
|
|
then
|
|
declare
|
|
L : constant Node_Id := Low_Bound (DS);
|
|
H : constant Node_Id := High_Bound (DS);
|
|
|
|
Llo : Uint;
|
|
Lhi : Uint;
|
|
LOK : Boolean;
|
|
Hlo : Uint;
|
|
Hhi : Uint;
|
|
HOK : Boolean;
|
|
|
|
begin
|
|
Determine_Range (L, LOK, Llo, Lhi);
|
|
Determine_Range (H, HOK, Hlo, Hhi);
|
|
|
|
-- If range of loop is null, issue warning
|
|
|
|
if (LOK and HOK) and then Llo > Hhi then
|
|
|
|
-- 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 parametrization.
|
|
|
|
if not Inside_A_Generic
|
|
and then not In_Instance
|
|
then
|
|
Error_Msg_N
|
|
("?loop range is null, loop will not execute",
|
|
DS);
|
|
end if;
|
|
|
|
-- Since we know the range of the loop is null,
|
|
-- set the appropriate flag to suppress any
|
|
-- warnings that would otherwise be issued in
|
|
-- the body of the loop that will not execute.
|
|
-- We do this even in the generic case, since
|
|
-- if it is dubious to warn on the null loop
|
|
-- itself, it is certainly dubious to warn for
|
|
-- conditions that occur inside it!
|
|
|
|
Set_Is_Null_Loop (Parent (N));
|
|
|
|
-- 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 can be positive.
|
|
|
|
-- 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 (LP)
|
|
and then Nkind (Original_Node (H)) =
|
|
N_Integer_Literal
|
|
and then (Intval (H) = Uint_0
|
|
or else
|
|
Intval (H) = Uint_1)
|
|
and then Lhi > Hhi
|
|
then
|
|
Error_Msg_N ("?loop range may be null", DS);
|
|
Error_Msg_N ("\?bounds may be wrong way round", DS);
|
|
end if;
|
|
end;
|
|
end if;
|
|
end;
|
|
end if;
|
|
end;
|
|
end if;
|
|
end Analyze_Iteration_Scheme;
|
|
|
|
-------------------
|
|
-- 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
|
|
Set_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_Statement --
|
|
----------------------------
|
|
|
|
procedure Analyze_Loop_Statement (N : Node_Id) is
|
|
Id : constant Node_Id := Identifier (N);
|
|
Iter : constant Node_Id := Iteration_Scheme (N);
|
|
Ent : Entity_Id;
|
|
|
|
begin
|
|
if Present (Id) then
|
|
|
|
-- Make name visible, e.g. for use in exit statements. Loop
|
|
-- labels are always considered to be referenced.
|
|
|
|
Analyze (Id);
|
|
Ent := Entity (Id);
|
|
Generate_Reference (Ent, N, ' ');
|
|
Generate_Definition (Ent);
|
|
|
|
-- If we found a label, mark its type. If not, ignore it, since it
|
|
-- means we have a conflicting declaration, which would already have
|
|
-- been diagnosed at declaration time. Set Label_Construct of the
|
|
-- implicit label declaration, which is not created by the parser
|
|
-- for generic units.
|
|
|
|
if Ekind (Ent) = E_Label then
|
|
Set_Ekind (Ent, E_Loop);
|
|
|
|
if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
|
|
Set_Label_Construct (Parent (Ent), N);
|
|
end if;
|
|
end if;
|
|
|
|
-- Case of no identifier present
|
|
|
|
else
|
|
Ent := New_Internal_Entity (E_Loop, Current_Scope, Sloc (N), 'L');
|
|
Set_Etype (Ent, Standard_Void_Type);
|
|
Set_Parent (Ent, N);
|
|
end if;
|
|
|
|
-- Kill current values on entry to loop, since statements in body
|
|
-- of loop may have been executed before the loop is entered.
|
|
-- Similarly we kill values after the loop, since we do not know
|
|
-- that the body of the loop was executed.
|
|
|
|
Kill_Current_Values;
|
|
New_Scope (Ent);
|
|
Analyze_Iteration_Scheme (Iter);
|
|
Analyze_Statements (Statements (N));
|
|
Process_End_Label (N, 'e', Ent);
|
|
End_Scope;
|
|
Kill_Current_Values;
|
|
|
|
-- Check for possible infinite loop which we can diagnose successfully.
|
|
-- The case we look for is a while loop which tests a local variable,
|
|
-- where there is no obvious direct or indirect update of the variable
|
|
-- within the body of the loop.
|
|
|
|
-- Note: we don't try to give a warning if condition actions are
|
|
-- present, since the loop structure can be very complex in this case.
|
|
|
|
if No (Iter)
|
|
or else No (Condition (Iter))
|
|
or else Present (Condition_Actions (Iter))
|
|
or else Debug_Flag_Dot_W
|
|
then
|
|
return;
|
|
end if;
|
|
|
|
-- Initial conditions met, see if condition is of right form
|
|
|
|
declare
|
|
Loc : Node_Id := Empty;
|
|
Var : Entity_Id := Empty;
|
|
|
|
function Has_Indirection (T : Entity_Id) return Boolean;
|
|
-- If the controlling variable is an access type, or is a record type
|
|
-- with access components, assume that it is changed indirectly and
|
|
-- suppress the warning. As a concession to low-level programming, in
|
|
-- particular within Declib, we also suppress warnings on a record
|
|
-- type that contains components of type Address or Short_Address.
|
|
|
|
procedure Find_Var (N : Node_Id);
|
|
-- Find whether the condition in a while-loop can be reduced to
|
|
-- a test on a single variable. Recurse if condition is negation.
|
|
|
|
---------------------
|
|
-- Has_Indirection --
|
|
---------------------
|
|
|
|
function Has_Indirection (T : Entity_Id) return Boolean is
|
|
Comp : Entity_Id;
|
|
Rec : Entity_Id;
|
|
|
|
begin
|
|
if Is_Access_Type (T) then
|
|
return True;
|
|
|
|
elsif Is_Private_Type (T)
|
|
and then Present (Full_View (T))
|
|
and then Is_Access_Type (Full_View (T))
|
|
then
|
|
return True;
|
|
|
|
elsif Is_Record_Type (T) then
|
|
Rec := T;
|
|
|
|
elsif Is_Private_Type (T)
|
|
and then Present (Full_View (T))
|
|
and then Is_Record_Type (Full_View (T))
|
|
then
|
|
Rec := Full_View (T);
|
|
else
|
|
return False;
|
|
end if;
|
|
|
|
Comp := First_Component (Rec);
|
|
while Present (Comp) loop
|
|
if Is_Access_Type (Etype (Comp))
|
|
or else Is_Descendent_Of_Address (Etype (Comp))
|
|
then
|
|
return True;
|
|
end if;
|
|
|
|
Next_Component (Comp);
|
|
end loop;
|
|
|
|
return False;
|
|
end Has_Indirection;
|
|
|
|
--------------
|
|
-- Find_Var --
|
|
--------------
|
|
|
|
procedure Find_Var (N : Node_Id) is
|
|
begin
|
|
-- Condition is a direct variable reference
|
|
|
|
if Is_Entity_Name (N)
|
|
and then not Is_Library_Level_Entity (Entity (N))
|
|
then
|
|
Loc := N;
|
|
|
|
-- Case of condition is a comparison with compile time known value
|
|
|
|
elsif Nkind (N) in N_Op_Compare then
|
|
if Is_Entity_Name (Left_Opnd (N))
|
|
and then Compile_Time_Known_Value (Right_Opnd (N))
|
|
then
|
|
Loc := Left_Opnd (N);
|
|
|
|
elsif Is_Entity_Name (Right_Opnd (N))
|
|
and then Compile_Time_Known_Value (Left_Opnd (N))
|
|
then
|
|
Loc := Right_Opnd (N);
|
|
|
|
else
|
|
return;
|
|
end if;
|
|
|
|
-- If condition is a negation, check whether the operand has the
|
|
-- proper form.
|
|
|
|
elsif Nkind (N) = N_Op_Not then
|
|
Find_Var (Right_Opnd (N));
|
|
|
|
-- Case of condition is function call with one parameter
|
|
|
|
elsif Nkind (N) = N_Function_Call then
|
|
declare
|
|
PA : constant List_Id := Parameter_Associations (N);
|
|
begin
|
|
if Present (PA)
|
|
and then List_Length (PA) = 1
|
|
and then Is_Entity_Name (First (PA))
|
|
then
|
|
Loc := First (PA);
|
|
else
|
|
return;
|
|
end if;
|
|
end;
|
|
|
|
else
|
|
return;
|
|
end if;
|
|
end Find_Var;
|
|
|
|
begin
|
|
Find_Var (Condition (Iter));
|
|
|
|
if Present (Loc) then
|
|
Var := Entity (Loc);
|
|
end if;
|
|
|
|
if Present (Var)
|
|
and then Ekind (Var) = E_Variable
|
|
and then not Is_Library_Level_Entity (Var)
|
|
and then Comes_From_Source (Var)
|
|
then
|
|
if Has_Indirection (Etype (Var)) then
|
|
|
|
-- Assume that the designated object is modified in some
|
|
-- other way, to avoid false positives.
|
|
|
|
return;
|
|
|
|
elsif Is_Volatile (Var) then
|
|
|
|
-- If the variable is marked as volatile, we assume that
|
|
-- the condition may be affected by other tasks.
|
|
|
|
return;
|
|
|
|
elsif Nkind (Original_Node (First (Statements (N))))
|
|
= N_Delay_Relative_Statement
|
|
or else Nkind (Original_Node (First (Statements (N))))
|
|
= N_Delay_Until_Statement
|
|
then
|
|
|
|
-- Assume that this is a multitasking program, and the
|
|
-- condition is affected by other threads.
|
|
|
|
return;
|
|
|
|
end if;
|
|
|
|
-- There no identifiable single variable in the condition
|
|
|
|
else
|
|
return;
|
|
end if;
|
|
|
|
-- Search for reference to variable in loop
|
|
|
|
Ref_Search : declare
|
|
function Test_Ref (N : Node_Id) return Traverse_Result;
|
|
-- Test for reference to variable in question. Returns Abandon
|
|
-- if matching reference found.
|
|
|
|
function Find_Ref is new Traverse_Func (Test_Ref);
|
|
-- Function to traverse body of procedure. Returns Abandon if
|
|
-- matching reference found.
|
|
|
|
--------------
|
|
-- Test_Ref --
|
|
--------------
|
|
|
|
function Test_Ref (N : Node_Id) return Traverse_Result is
|
|
begin
|
|
-- Waste of time to look at iteration scheme
|
|
|
|
if N = Iter then
|
|
return Skip;
|
|
|
|
-- Direct reference to variable in question
|
|
|
|
elsif Is_Entity_Name (N)
|
|
and then Present (Entity (N))
|
|
and then Entity (N) = Var
|
|
and then May_Be_Lvalue (N)
|
|
then
|
|
return Abandon;
|
|
|
|
-- Reference to variable renaming variable in question
|
|
|
|
elsif Is_Entity_Name (N)
|
|
and then Present (Entity (N))
|
|
and then Ekind (Entity (N)) = E_Variable
|
|
and then Present (Renamed_Object (Entity (N)))
|
|
and then Is_Entity_Name (Renamed_Object (Entity (N)))
|
|
and then Entity (Renamed_Object (Entity (N))) = Var
|
|
and then May_Be_Lvalue (N)
|
|
then
|
|
return Abandon;
|
|
|
|
-- Calls to subprograms are OK, unless the subprogram is
|
|
-- within the scope of the entity in question and could
|
|
-- therefore possibly modify it
|
|
|
|
elsif Nkind (N) = N_Procedure_Call_Statement
|
|
or else Nkind (N) = N_Function_Call
|
|
then
|
|
if not Is_Entity_Name (Name (N))
|
|
or else Scope_Within (Entity (Name (N)), Scope (Var))
|
|
then
|
|
return Abandon;
|
|
end if;
|
|
end if;
|
|
|
|
-- All OK, continue scan
|
|
|
|
return OK;
|
|
end Test_Ref;
|
|
|
|
-- Start of processing for Ref_Search
|
|
|
|
begin
|
|
if Find_Ref (N) = OK then
|
|
Error_Msg_NE
|
|
("variable& is not modified in loop body?", Loc, Var);
|
|
Error_Msg_N
|
|
("\possible infinite loop", Loc);
|
|
end if;
|
|
end Ref_Search;
|
|
end;
|
|
end Analyze_Loop_Statement;
|
|
|
|
----------------------------
|
|
-- Analyze_Null_Statement --
|
|
----------------------------
|
|
|
|
-- Note: the semantics of the null statement is implemented by a single
|
|
-- null statement, too bad everything isn't as simple as this!
|
|
|
|
procedure Analyze_Null_Statement (N : Node_Id) is
|
|
pragma Warnings (Off, N);
|
|
begin
|
|
null;
|
|
end Analyze_Null_Statement;
|
|
|
|
------------------------
|
|
-- Analyze_Statements --
|
|
------------------------
|
|
|
|
procedure Analyze_Statements (L : List_Id) is
|
|
S : Node_Id;
|
|
Lab : Entity_Id;
|
|
|
|
begin
|
|
-- The labels declared in the statement list are reachable from
|
|
-- statements in the list. We do this as a prepass so that any
|
|
-- goto statement will be properly flagged if its target is not
|
|
-- reachable. This is not required, but is nice behavior!
|
|
|
|
S := First (L);
|
|
while Present (S) loop
|
|
if Nkind (S) = N_Label then
|
|
Analyze (Identifier (S));
|
|
Lab := Entity (Identifier (S));
|
|
|
|
-- If we found a label mark it as reachable
|
|
|
|
if Ekind (Lab) = E_Label then
|
|
Generate_Definition (Lab);
|
|
Set_Reachable (Lab);
|
|
|
|
if Nkind (Parent (Lab)) = N_Implicit_Label_Declaration then
|
|
Set_Label_Construct (Parent (Lab), S);
|
|
end if;
|
|
|
|
-- If we failed to find a label, it means the implicit declaration
|
|
-- of the label was hidden. A for-loop parameter can do this to
|
|
-- a label with the same name inside the loop, since the implicit
|
|
-- label declaration is in the innermost enclosing body or block
|
|
-- statement.
|
|
|
|
else
|
|
Error_Msg_Sloc := Sloc (Lab);
|
|
Error_Msg_N
|
|
("implicit label declaration for & is hidden#",
|
|
Identifier (S));
|
|
end if;
|
|
end if;
|
|
|
|
Next (S);
|
|
end loop;
|
|
|
|
-- Perform semantic analysis on all statements
|
|
|
|
Conditional_Statements_Begin;
|
|
|
|
S := First (L);
|
|
while Present (S) loop
|
|
Analyze (S);
|
|
Next (S);
|
|
end loop;
|
|
|
|
Conditional_Statements_End;
|
|
|
|
-- Make labels unreachable. Visibility is not sufficient, because
|
|
-- labels in one if-branch for example are not reachable from the
|
|
-- other branch, even though their declarations are in the enclosing
|
|
-- declarative part.
|
|
|
|
S := First (L);
|
|
while Present (S) loop
|
|
if Nkind (S) = N_Label then
|
|
Set_Reachable (Entity (Identifier (S)), False);
|
|
end if;
|
|
|
|
Next (S);
|
|
end loop;
|
|
end Analyze_Statements;
|
|
|
|
----------------------------
|
|
-- Check_Unreachable_Code --
|
|
----------------------------
|
|
|
|
procedure Check_Unreachable_Code (N : Node_Id) is
|
|
Error_Loc : Source_Ptr;
|
|
P : Node_Id;
|
|
|
|
begin
|
|
if Is_List_Member (N)
|
|
and then Comes_From_Source (N)
|
|
then
|
|
declare
|
|
Nxt : Node_Id;
|
|
|
|
begin
|
|
Nxt := Original_Node (Next (N));
|
|
|
|
-- If a label follows us, then we never have dead code, since
|
|
-- someone could branch to the label, so we just ignore it.
|
|
|
|
if Nkind (Nxt) = N_Label then
|
|
return;
|
|
|
|
-- Otherwise see if we have a real statement following us
|
|
|
|
elsif Present (Nxt)
|
|
and then Comes_From_Source (Nxt)
|
|
and then Is_Statement (Nxt)
|
|
then
|
|
-- Special very annoying exception. If we have a return that
|
|
-- follows a raise, then we allow it without a warning, since
|
|
-- the Ada RM annoyingly requires a useless return here!
|
|
|
|
if Nkind (Original_Node (N)) /= N_Raise_Statement
|
|
or else Nkind (Nxt) /= N_Return_Statement
|
|
then
|
|
-- The rather strange shenanigans with the warning message
|
|
-- here reflects the fact that Kill_Dead_Code is very good
|
|
-- at removing warnings in deleted code, and this is one
|
|
-- warning we would prefer NOT to have removed :-)
|
|
|
|
Error_Loc := Sloc (Nxt);
|
|
|
|
-- If we have unreachable code, analyze and remove the
|
|
-- unreachable code, since it is useless and we don't
|
|
-- want to generate junk warnings.
|
|
|
|
-- We skip this step if we are not in code generation mode.
|
|
-- This is the one case where we remove dead code in the
|
|
-- semantics as opposed to the expander, and we do not want
|
|
-- to remove code if we are not in code generation mode,
|
|
-- since this messes up the ASIS trees.
|
|
|
|
-- Note that one might react by moving the whole circuit to
|
|
-- exp_ch5, but then we lose the warning in -gnatc mode.
|
|
|
|
if Operating_Mode = Generate_Code then
|
|
loop
|
|
Nxt := Next (N);
|
|
|
|
-- Quit deleting when we have nothing more to delete
|
|
-- or if we hit a label (since someone could transfer
|
|
-- control to a label, so we should not delete it).
|
|
|
|
exit when No (Nxt) or else Nkind (Nxt) = N_Label;
|
|
|
|
-- Statement/declaration is to be deleted
|
|
|
|
Analyze (Nxt);
|
|
Remove (Nxt);
|
|
Kill_Dead_Code (Nxt);
|
|
end loop;
|
|
end if;
|
|
|
|
-- Now issue the warning
|
|
|
|
Error_Msg ("?unreachable code", Error_Loc);
|
|
end if;
|
|
|
|
-- If the unconditional transfer of control instruction is
|
|
-- the last statement of a sequence, then see if our parent
|
|
-- is one of the constructs for which we count unblocked exits,
|
|
-- and if so, adjust the count.
|
|
|
|
else
|
|
P := Parent (N);
|
|
|
|
-- Statements in THEN part or ELSE part of IF statement
|
|
|
|
if Nkind (P) = N_If_Statement then
|
|
null;
|
|
|
|
-- Statements in ELSIF part of an IF statement
|
|
|
|
elsif Nkind (P) = N_Elsif_Part then
|
|
P := Parent (P);
|
|
pragma Assert (Nkind (P) = N_If_Statement);
|
|
|
|
-- Statements in CASE statement alternative
|
|
|
|
elsif Nkind (P) = N_Case_Statement_Alternative then
|
|
P := Parent (P);
|
|
pragma Assert (Nkind (P) = N_Case_Statement);
|
|
|
|
-- Statements in body of block
|
|
|
|
elsif Nkind (P) = N_Handled_Sequence_Of_Statements
|
|
and then Nkind (Parent (P)) = N_Block_Statement
|
|
then
|
|
null;
|
|
|
|
-- Statements in exception handler in a block
|
|
|
|
elsif Nkind (P) = N_Exception_Handler
|
|
and then Nkind (Parent (P)) = N_Handled_Sequence_Of_Statements
|
|
and then Nkind (Parent (Parent (P))) = N_Block_Statement
|
|
then
|
|
null;
|
|
|
|
-- None of these cases, so return
|
|
|
|
else
|
|
return;
|
|
end if;
|
|
|
|
-- This was one of the cases we are looking for (i.e. the
|
|
-- parent construct was IF, CASE or block) so decrement count.
|
|
|
|
Unblocked_Exit_Count := Unblocked_Exit_Count - 1;
|
|
end if;
|
|
end;
|
|
end if;
|
|
end Check_Unreachable_Code;
|
|
|
|
end Sem_Ch5;
|