3839 lines
138 KiB
Ada
3839 lines
138 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) 1992-2016, 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 3, 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 COPYING3. If not, go to --
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-- http://www.gnu.org/licenses for a complete copy of the license. --
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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 Aspects; use Aspects;
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with Atree; use Atree;
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with Checks; use Checks;
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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_Ch6; use Exp_Ch6;
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with Exp_Util; use Exp_Util;
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with Freeze; use Freeze;
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with Ghost; use Ghost;
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with Lib; use Lib;
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with Lib.Xref; use Lib.Xref;
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with Namet; use Namet;
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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 Restrict; use Restrict;
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with Rident; use Rident;
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with Sem; use Sem;
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with Sem_Aux; use Sem_Aux;
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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_Ch6; use Sem_Ch6;
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with Sem_Ch8; use Sem_Ch8;
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with Sem_Dim; use Sem_Dim;
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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 not
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-- blocked by unconditional transfer instructions: for IF and CASE, these
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-- are the branches of the conditional; for a block, they are the statement
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-- sequence of the block, and the statement sequences of any exception
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-- handlers that are part of the block. When processing is complete, if
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-- this count is zero, it means that control cannot fall through the IF,
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-- CASE or block statement. This is used for the generation of warning
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-- messages. This variable is recursively saved on entry to processing the
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-- construct, and restored on exit.
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procedure Preanalyze_Range (R_Copy : Node_Id);
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-- Determine expected type of range or domain of iteration of Ada 2012
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-- loop by analyzing separate copy. Do the analysis and resolution of the
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-- copy of the bound(s) with expansion disabled, to prevent the generation
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-- of finalization actions. This prevents memory leaks when the bounds
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-- contain calls to functions returning controlled arrays or when the
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-- domain of iteration is a container.
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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 is not
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-- 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 is the
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-- nominal subtype. This procedure is used to deal with cases where the
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-- 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 flagged
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-- 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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declare
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Ent : constant Entity_Id := Entity (N);
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begin
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if Ekind (Ent) = 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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return;
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-- Renamings of protected private components are turned into
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-- constants when compiling a protected function. In the case
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-- of single protected types, the private component appears
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-- directly.
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elsif (Is_Prival (Ent)
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and then
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(Ekind (Current_Scope) = E_Function
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or else Ekind (Enclosing_Dynamic_Scope
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(Current_Scope)) = E_Function))
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or else
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(Ekind (Ent) = E_Component
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and then Is_Protected_Type (Scope (Ent)))
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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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return;
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elsif Ekind (Ent) = E_Loop_Parameter then
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Error_Msg_N ("assignment to loop parameter not allowed", N);
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return;
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end if;
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end;
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-- For indexed components, test prefix if it is in array. We do not
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-- want to recurse for cases where the prefix is a pointer, since we
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-- may get a message confusing the pointer and what it references.
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elsif Nkind (N) = N_Indexed_Component
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and then Is_Array_Type (Etype (Prefix (N)))
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then
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Diagnose_Non_Variable_Lhs (Prefix (N));
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return;
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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 ("assignment to discriminant not allowed", N);
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return;
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-- For selection from record, diagnose prefix, but note that again
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-- we only do this for a record, not e.g. for a pointer.
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elsif Is_Record_Type (Etype (Prefix (N))) then
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Diagnose_Non_Variable_Lhs (Prefix (N));
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return;
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end if;
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end if;
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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 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). If the
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-- operand is the actual in an entry declaration, then within the
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-- accept statement it is replaced with a local renaming, which may
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-- 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_In (Entity (Opnd),
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E_In_Out_Parameter,
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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 Nkind_In (Opnd, N_Selected_Component, 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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-- Local variables
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Save_Ghost_Mode : constant Ghost_Mode_Type := Ghost_Mode;
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-- Start of processing for Analyze_Assignment
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begin
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Mark_Coextensions (N, Rhs);
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-- Analyze the target of the assignment first in case the expression
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-- contains references to Ghost entities. The checks that verify the
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-- proper use of a Ghost entity need to know the enclosing context.
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Analyze (Lhs);
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-- An assignment statement is Ghost when the left hand side denotes a
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-- Ghost entity. Set the mode now to ensure that any nodes generated
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-- during analysis and expansion are properly marked as Ghost.
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Set_Ghost_Mode (N);
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Analyze (Rhs);
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-- Ensure that we never do an assignment on a variable marked as
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-- as Safe_To_Reevaluate.
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pragma Assert (not Is_Entity_Name (Lhs)
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or else Ekind (Entity (Lhs)) /= E_Variable
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or else not Is_Safe_To_Reevaluate (Entity (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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-- An indexed component with generalized indexing is always
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-- overloaded with the corresponding dereference. Discard the
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-- interpretation that yields a reference type, which is not
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-- assignable.
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if Nkind (Lhs) = N_Indexed_Component
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and then Present (Generalized_Indexing (Lhs))
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and then Has_Implicit_Dereference (It.Typ)
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then
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null;
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elsif 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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Ghost_Mode := Save_Ghost_Mode;
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return;
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end if;
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end if;
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-- The resulting assignment type is T1, so now we will resolve the left
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-- hand side of the assignment using this determined type.
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Resolve (Lhs, T1);
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-- Cases where Lhs is not a variable
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-- Cases where Lhs is not a variable. In an instance or an inlined body
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-- no need for further check because assignment was legal in template.
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if In_Inlined_Body then
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null;
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elsif not Is_Variable (Lhs) then
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-- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
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-- 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_2005 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 Is_Expanded_Priority_Attribute (Ent)
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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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Ghost_Mode := Save_Ghost_Mode;
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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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Ghost_Mode := Save_Ghost_Mode;
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return;
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-- Error of assigning to limited type. We do however allow this in
|
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-- certain cases where the front end generates the assignments.
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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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-- CPP constructors can only be called in declarations
|
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if Is_CPP_Constructor_Call (Rhs) then
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Error_Msg_N ("invalid use of 'C'P'P constructor", Rhs);
|
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else
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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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end if;
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Ghost_Mode := Save_Ghost_Mode;
|
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return;
|
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-- A class-wide type may be a limited view. This illegal case is not
|
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-- caught by previous checks.
|
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elsif Ekind (T1) = E_Class_Wide_Type
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and then From_Limited_With (T1)
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then
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Error_Msg_NE ("invalid use of limited view of&", Lhs, T1);
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return;
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-- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
|
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-- abstract. This is only checked when the assignment Comes_From_Source,
|
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-- because in some cases the expander generates such assignments (such
|
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-- in the _assign operation for an abstract type).
|
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elsif Is_Abstract_Type (T1) and then Comes_From_Source (N) then
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Error_Msg_N
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("target of assignment operation must not be abstract", Lhs);
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end if;
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|
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-- Resolution may have updated the subtype, in case the left-hand side
|
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-- is a private protected component. Use the correct subtype to avoid
|
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-- scoping issues in the back-end.
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T1 := Etype (Lhs);
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|
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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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|
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-- with Pkg; use Acc;
|
|
-- 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
|
|
Error_Msg_N ("invalid use of incomplete type", Lhs);
|
|
Kill_Lhs;
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
end if;
|
|
|
|
-- Now we can complete the resolution of the right hand side
|
|
|
|
Set_Assignment_Type (Lhs, T1);
|
|
Resolve (Rhs, T1);
|
|
|
|
-- 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;
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
end if;
|
|
|
|
T2 := Etype (Rhs);
|
|
|
|
if not Covers (T1, T2) then
|
|
Wrong_Type (Rhs, Etype (Lhs));
|
|
Kill_Lhs;
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
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;
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
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);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
return;
|
|
|
|
-- 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
|
|
Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
|
|
|
|
-- 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 Lsh 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 (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, 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) > 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;
|
|
|
|
-- 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.
|
|
|
|
if Nkind (Lhs) = N_Type_Conversion
|
|
and then Has_Invariants (Etype (Expression (Lhs)))
|
|
and then Comes_From_Source (Expression (Lhs))
|
|
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.
|
|
|
|
-- 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)
|
|
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);
|
|
Ghost_Mode := Save_Ghost_Mode;
|
|
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 not Ekind_In (Id, 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
|
|
-- In SPARK mode, we reject block statements. Note that the case of
|
|
-- block statements generated by the expander is fine.
|
|
|
|
if Nkind (Original_Node (N)) = N_Block_Statement then
|
|
Check_SPARK_05_Restriction ("block statement is not allowed", N);
|
|
end if;
|
|
|
|
-- 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
|
|
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));
|
|
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);
|
|
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 : Node_Id;
|
|
Exp_Type : Entity_Id;
|
|
Exp_Btype : Entity_Id;
|
|
Last_Choice : Nat;
|
|
|
|
Others_Present : Boolean;
|
|
-- Indicates if Others was present
|
|
|
|
pragma Warnings (Off, Last_Choice);
|
|
-- Don't care about assigned value
|
|
|
|
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 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
|
|
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_In (Ent, E_Variable,
|
|
E_In_Out_Parameter,
|
|
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;
|
|
|
|
-- 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 procedures to analyzwe and check discrete choices
|
|
|
|
Analyze_Choices (Alternatives (N), Exp_Type);
|
|
Check_Choices (N, Alternatives (N), Exp_Type, Others_Present);
|
|
|
|
-- Case statement with single OTHERS alternative not allowed in SPARK
|
|
|
|
if Others_Present and then List_Length (Alternatives (N)) = 1 then
|
|
Check_SPARK_05_Restriction
|
|
("OTHERS as unique case alternative is not allowed", N);
|
|
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;
|
|
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
|
|
if Has_Loop_In_Inner_Open_Scopes (U_Name) then
|
|
Check_SPARK_05_Restriction
|
|
("exit label must name the closest enclosing loop", N);
|
|
end if;
|
|
|
|
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;
|
|
|
|
-- In SPARK mode, verify that the exit statement respects the SPARK
|
|
-- restrictions.
|
|
|
|
if Present (Cond) then
|
|
if Nkind (Parent (N)) /= N_Loop_Statement then
|
|
Check_SPARK_05_Restriction
|
|
("exit with when clause must be directly in loop", N);
|
|
end if;
|
|
|
|
else
|
|
if Nkind (Parent (N)) /= N_If_Statement then
|
|
if Nkind (Parent (N)) = N_Elsif_Part then
|
|
Check_SPARK_05_Restriction
|
|
("exit must be in IF without ELSIF", N);
|
|
else
|
|
Check_SPARK_05_Restriction ("exit must be directly in IF", N);
|
|
end if;
|
|
|
|
elsif Nkind (Parent (Parent (N))) /= N_Loop_Statement then
|
|
Check_SPARK_05_Restriction
|
|
("exit must be in IF directly in loop", N);
|
|
|
|
-- First test the presence of ELSE, so that an exit in an ELSE leads
|
|
-- to an error mentioning the ELSE.
|
|
|
|
elsif Present (Else_Statements (Parent (N))) then
|
|
Check_SPARK_05_Restriction ("exit must be in IF without ELSE", N);
|
|
|
|
-- An exit in an ELSIF does not reach here, as it would have been
|
|
-- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
|
|
|
|
elsif Present (Elsif_Parts (Parent (N))) then
|
|
Check_SPARK_05_Restriction ("exit must be in IF without ELSIF", N);
|
|
end if;
|
|
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
|
|
Check_SPARK_05_Restriction ("goto statement is not allowed", N);
|
|
|
|
-- 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 not Ekind_In (Scope_Id, 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_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 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);
|
|
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
|
|
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
|
|
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.
|
|
|
|
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)
|
|
and then not Is_Array_Type (Typ)
|
|
and then not Is_Reversible_Iterator (Typ)
|
|
then
|
|
Error_Msg_NE
|
|
("container type does not support reverse iteration", N, Typ);
|
|
end if;
|
|
end Check_Reverse_Iteration;
|
|
|
|
---------------------
|
|
-- 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;
|
|
|
|
-- Local variables
|
|
|
|
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;
|
|
Typ : Entity_Id;
|
|
|
|
-- 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;
|
|
else
|
|
Analyze (Subt);
|
|
end if;
|
|
|
|
-- Save entity of subtype indication for subsequent check
|
|
|
|
Bas := Entity (Subt);
|
|
end if;
|
|
|
|
Preanalyze_Range (Iter_Name);
|
|
|
|
-- Set the kind of the loop variable, which is not visible within
|
|
-- the iterator name.
|
|
|
|
Set_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
|
|
if No (Iterator) then
|
|
null; -- error reported below.
|
|
|
|
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 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)
|
|
|
|
-- Do not perform this expansion for ASIS and 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
|
|
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. Pre-analysis
|
|
-- 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;
|
|
|
|
-- 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));
|
|
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, Etype (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.
|
|
|
|
Set_Is_Aliased (Def_Id, Has_Aliased_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
|
|
-- dowmain 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;
|
|
|
|
if Present (Subt)
|
|
and then
|
|
(Base_Type (Bas) /= Base_Type (Component_Type (Typ))
|
|
or else
|
|
not Subtypes_Statically_Match (Bas, Component_Type (Typ)))
|
|
then
|
|
Error_Msg_N
|
|
("subtype indication does not match component type", Subt);
|
|
end if;
|
|
|
|
-- 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
|
|
|
|
Set_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
|
|
Set_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));
|
|
end if;
|
|
end;
|
|
|
|
-- 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));
|
|
|
|
-- If subtype indication was given, verify that it covers
|
|
-- the element type of the container.
|
|
|
|
if Present (Subt)
|
|
and then (not Covers (Bas, Etype (Def_Id))
|
|
or else not Subtypes_Statically_Match
|
|
(Bas, Etype (Def_Id)))
|
|
then
|
|
Error_Msg_N
|
|
("subtype indication does not match element type",
|
|
Subt);
|
|
end if;
|
|
|
|
-- 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
|
|
Set_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_In
|
|
(Entity (Selector_Name (Orig_Iter_Name)),
|
|
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;
|
|
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
|
|
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_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.
|
|
|
|
function Has_Call_Using_Secondary_Stack (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 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.
|
|
|
|
--------------------------------------
|
|
-- 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) then
|
|
Set_No_Dynamic_Predicate_On_Actual (T);
|
|
end if;
|
|
end Check_Predicate_Use;
|
|
|
|
------------------------------------
|
|
-- Has_Call_Using_Secondary_Stack --
|
|
------------------------------------
|
|
|
|
function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean is
|
|
|
|
function Check_Call (N : Node_Id) return Traverse_Result;
|
|
-- Check if N is a function call which uses the secondary stack
|
|
|
|
----------------
|
|
-- Check_Call --
|
|
----------------
|
|
|
|
function Check_Call (N : Node_Id) return Traverse_Result is
|
|
Nam : Node_Id;
|
|
Subp : Entity_Id;
|
|
Return_Typ : Entity_Id;
|
|
|
|
begin
|
|
if Nkind (N) = N_Function_Call then
|
|
Nam := Name (N);
|
|
|
|
-- Call using access to subprogram with explicit dereference
|
|
|
|
if Nkind (Nam) = N_Explicit_Dereference then
|
|
Subp := Etype (Nam);
|
|
|
|
-- Call using a selected component notation or Ada 2005 object
|
|
-- operation notation
|
|
|
|
elsif Nkind (Nam) = N_Selected_Component then
|
|
Subp := Entity (Selector_Name (Nam));
|
|
|
|
-- Common case
|
|
|
|
else
|
|
Subp := Entity (Nam);
|
|
end if;
|
|
|
|
Return_Typ := Etype (Subp);
|
|
|
|
if Is_Composite_Type (Return_Typ)
|
|
and then not Is_Constrained (Return_Typ)
|
|
then
|
|
return Abandon;
|
|
|
|
elsif Sec_Stack_Needed_For_Return (Subp) then
|
|
return Abandon;
|
|
end if;
|
|
end if;
|
|
|
|
-- Continue traversing the tree
|
|
|
|
return OK;
|
|
end Check_Call;
|
|
|
|
function Check_Calls is new Traverse_Func (Check_Call);
|
|
|
|
-- Start of processing for Has_Call_Using_Secondary_Stack
|
|
|
|
begin
|
|
return Check_Calls (N) = Abandon;
|
|
end Has_Call_Using_Secondary_Stack;
|
|
|
|
--------------------
|
|
-- 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_In (Analyzed_Bound, N_Integer_Literal,
|
|
N_Character_Literal)
|
|
or else Is_Entity_Name (Analyzed_Bound)
|
|
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_Call_Using_Secondary_Stack (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;
|
|
|
|
-- Loop parameter specification must include subtype mark in SPARK
|
|
|
|
if Nkind (DS) = N_Range then
|
|
Check_SPARK_05_Restriction
|
|
("loop parameter specification must include subtype mark", N);
|
|
end if;
|
|
|
|
-- 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 Nam_In (Attribute_Name (DS_Copy),
|
|
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);
|
|
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.
|
|
|
|
Set_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 pre-analyzed 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;
|
|
|
|
Make_Index (DS, N, In_Iter_Schm => True);
|
|
Set_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.
|
|
|
|
if No (Etype (Id))
|
|
or else Etype (Id) = Any_Type
|
|
or else
|
|
(Present (Etype (Id))
|
|
and then Is_Itype (Etype (Id))
|
|
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_In (DS, 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;
|
|
|
|
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
|
|
|
|
-- 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 Compile_Time_Compare
|
|
(L, H, Assume_Valid => False) = GT
|
|
then
|
|
-- Since we know the range of the loop is null, set the
|
|
-- appropriate flag to remove the loop entirely during
|
|
-- expansion.
|
|
|
|
Set_Is_Null_Loop (Loop_Nod);
|
|
|
|
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 and in
|
|
-- this case we do not set the Is_Null_Loop flag since
|
|
-- the loop may execute.
|
|
|
|
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;
|
|
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 => null;
|
|
end;
|
|
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
|
|
|
|
function Is_Container_Iterator (Iter : Node_Id) return Boolean;
|
|
-- Given a loop iteration scheme, determine whether it is an Ada 2012
|
|
-- container iteration.
|
|
|
|
function Is_Wrapped_In_Block (N : Node_Id) return Boolean;
|
|
-- Determine whether loop statement N has been wrapped in a block to
|
|
-- capture finalization actions that may be generated for container
|
|
-- iterators. Prevents infinite recursion when block is analyzed.
|
|
-- Routine is a noop if loop is single statement within source block.
|
|
|
|
---------------------------
|
|
-- Is_Container_Iterator --
|
|
---------------------------
|
|
|
|
function Is_Container_Iterator (Iter : Node_Id) return Boolean is
|
|
begin
|
|
-- Infinite loop
|
|
|
|
if No (Iter) then
|
|
return False;
|
|
|
|
-- While loop
|
|
|
|
elsif Present (Condition (Iter)) then
|
|
return False;
|
|
|
|
-- for Def_Id in [reverse] Name loop
|
|
-- for Def_Id [: Subtype_Indication] of [reverse] Name loop
|
|
|
|
elsif Present (Iterator_Specification (Iter)) then
|
|
declare
|
|
Nam : constant Node_Id := Name (Iterator_Specification (Iter));
|
|
Nam_Copy : Node_Id;
|
|
|
|
begin
|
|
Nam_Copy := New_Copy_Tree (Nam);
|
|
Set_Parent (Nam_Copy, Parent (Nam));
|
|
Preanalyze_Range (Nam_Copy);
|
|
|
|
-- The only two options here are iteration over a container or
|
|
-- an array.
|
|
|
|
return not Is_Array_Type (Etype (Nam_Copy));
|
|
end;
|
|
|
|
-- for Def_Id in [reverse] Discrete_Subtype_Definition loop
|
|
|
|
else
|
|
declare
|
|
LP : constant Node_Id := Loop_Parameter_Specification (Iter);
|
|
DS : constant Node_Id := Discrete_Subtype_Definition (LP);
|
|
DS_Copy : Node_Id;
|
|
|
|
begin
|
|
DS_Copy := New_Copy_Tree (DS);
|
|
Set_Parent (DS_Copy, Parent (DS));
|
|
Preanalyze_Range (DS_Copy);
|
|
|
|
-- Check for a call to Iterate () or an expression with
|
|
-- an iterator type.
|
|
|
|
return
|
|
(Nkind (DS_Copy) = N_Function_Call
|
|
and then Needs_Finalization (Etype (DS_Copy)))
|
|
or else Is_Iterator (Etype (DS_Copy));
|
|
end;
|
|
end if;
|
|
end Is_Container_Iterator;
|
|
|
|
-------------------------
|
|
-- Is_Wrapped_In_Block --
|
|
-------------------------
|
|
|
|
function Is_Wrapped_In_Block (N : Node_Id) return Boolean is
|
|
HSS : Node_Id;
|
|
Stat : Node_Id;
|
|
|
|
begin
|
|
|
|
-- Check if current scope is a block that is not a transient block.
|
|
|
|
if Ekind (Current_Scope) /= E_Block
|
|
or else No (Block_Node (Current_Scope))
|
|
then
|
|
return False;
|
|
|
|
else
|
|
HSS :=
|
|
Handled_Statement_Sequence (Parent (Block_Node (Current_Scope)));
|
|
|
|
-- Skip leading pragmas that may be introduced for invariant and
|
|
-- predicate checks.
|
|
|
|
Stat := First (Statements (HSS));
|
|
while Present (Stat) and then Nkind (Stat) = N_Pragma loop
|
|
Stat := Next (Stat);
|
|
end loop;
|
|
|
|
return Stat = N and then No (Next (Stat));
|
|
end if;
|
|
end Is_Wrapped_In_Block;
|
|
|
|
-- Local declarations
|
|
|
|
Id : constant Node_Id := Identifier (N);
|
|
Iter : constant Node_Id := Iteration_Scheme (N);
|
|
Loc : constant Source_Ptr := Sloc (N);
|
|
Ent : Entity_Id;
|
|
Stmt : Node_Id;
|
|
|
|
-- Start of processing for Analyze_Loop_Statement
|
|
|
|
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);
|
|
|
|
-- Guard against serious error (typically, a scope mismatch when
|
|
-- semantic analysis is requested) by creating loop entity to
|
|
-- continue analysis.
|
|
|
|
if No (Ent) then
|
|
if Total_Errors_Detected /= 0 then
|
|
Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
|
|
else
|
|
raise Program_Error;
|
|
end if;
|
|
|
|
-- Verify that the loop name is hot hidden by an unrelated
|
|
-- declaration in an inner scope.
|
|
|
|
elsif Ekind (Ent) /= E_Label and then Ekind (Ent) /= E_Loop then
|
|
Error_Msg_Sloc := Sloc (Ent);
|
|
Error_Msg_N ("implicit label declaration for & is hidden#", Id);
|
|
|
|
if Present (Homonym (Ent))
|
|
and then Ekind (Homonym (Ent)) = E_Label
|
|
then
|
|
Set_Entity (Id, Ent);
|
|
Set_Ekind (Ent, E_Loop);
|
|
end if;
|
|
|
|
else
|
|
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;
|
|
end if;
|
|
|
|
-- Case of no identifier present. Create one and attach it to the
|
|
-- loop statement for use as a scope and as a reference for later
|
|
-- expansions. Indicate that the label does not come from source,
|
|
-- and attach it to the loop statement so it is part of the tree,
|
|
-- even without a full declaration.
|
|
|
|
else
|
|
Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
|
|
Set_Etype (Ent, Standard_Void_Type);
|
|
Set_Identifier (N, New_Occurrence_Of (Ent, Loc));
|
|
Set_Parent (Ent, N);
|
|
Set_Has_Created_Identifier (N);
|
|
end if;
|
|
|
|
-- Iteration over a container in Ada 2012 involves the creation of a
|
|
-- controlled iterator object. Wrap the loop in a block to ensure the
|
|
-- timely finalization of the iterator and release of container locks.
|
|
-- The same applies to the use of secondary stack when obtaining an
|
|
-- iterator.
|
|
|
|
if Ada_Version >= Ada_2012
|
|
and then Is_Container_Iterator (Iter)
|
|
and then not Is_Wrapped_In_Block (N)
|
|
then
|
|
declare
|
|
Block_Nod : Node_Id;
|
|
Block_Id : Entity_Id;
|
|
|
|
begin
|
|
Block_Nod :=
|
|
Make_Block_Statement (Loc,
|
|
Declarations => New_List,
|
|
Handled_Statement_Sequence =>
|
|
Make_Handled_Sequence_Of_Statements (Loc,
|
|
Statements => New_List (Relocate_Node (N))));
|
|
|
|
Add_Block_Identifier (Block_Nod, Block_Id);
|
|
|
|
-- The expansion of iterator loops generates an iterator in order
|
|
-- to traverse the elements of a container:
|
|
|
|
-- Iter : <iterator type> := Iterate (Container)'reference;
|
|
|
|
-- The iterator is controlled and returned on the secondary stack.
|
|
-- The analysis of the call to Iterate establishes a transient
|
|
-- scope to deal with the secondary stack management, but never
|
|
-- really creates a physical block as this would kill the iterator
|
|
-- too early (see Wrap_Transient_Declaration). To address this
|
|
-- case, mark the generated block as needing secondary stack
|
|
-- management.
|
|
|
|
Set_Uses_Sec_Stack (Block_Id);
|
|
|
|
Rewrite (N, Block_Nod);
|
|
Analyze (N);
|
|
return;
|
|
end;
|
|
end if;
|
|
|
|
-- Kill current values on entry to loop, since statements in the body of
|
|
-- the 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;
|
|
Push_Scope (Ent);
|
|
Analyze_Iteration_Scheme (Iter);
|
|
|
|
-- Check for following case which merits a warning if the type E of is
|
|
-- a multi-dimensional array (and no explicit subscript ranges present).
|
|
|
|
-- for J in E'Range
|
|
-- for K in E'Range
|
|
|
|
if Present (Iter)
|
|
and then Present (Loop_Parameter_Specification (Iter))
|
|
then
|
|
declare
|
|
LPS : constant Node_Id := Loop_Parameter_Specification (Iter);
|
|
DSD : constant Node_Id :=
|
|
Original_Node (Discrete_Subtype_Definition (LPS));
|
|
begin
|
|
if Nkind (DSD) = N_Attribute_Reference
|
|
and then Attribute_Name (DSD) = Name_Range
|
|
and then No (Expressions (DSD))
|
|
then
|
|
declare
|
|
Typ : constant Entity_Id := Etype (Prefix (DSD));
|
|
begin
|
|
if Is_Array_Type (Typ)
|
|
and then Number_Dimensions (Typ) > 1
|
|
and then Nkind (Parent (N)) = N_Loop_Statement
|
|
and then Present (Iteration_Scheme (Parent (N)))
|
|
then
|
|
declare
|
|
OIter : constant Node_Id :=
|
|
Iteration_Scheme (Parent (N));
|
|
OLPS : constant Node_Id :=
|
|
Loop_Parameter_Specification (OIter);
|
|
ODSD : constant Node_Id :=
|
|
Original_Node (Discrete_Subtype_Definition (OLPS));
|
|
begin
|
|
if Nkind (ODSD) = N_Attribute_Reference
|
|
and then Attribute_Name (ODSD) = Name_Range
|
|
and then No (Expressions (ODSD))
|
|
and then Etype (Prefix (ODSD)) = Typ
|
|
then
|
|
Error_Msg_Sloc := Sloc (ODSD);
|
|
Error_Msg_N
|
|
("inner range same as outer range#??", DSD);
|
|
end if;
|
|
end;
|
|
end if;
|
|
end;
|
|
end if;
|
|
end;
|
|
end if;
|
|
|
|
-- Analyze the statements of the body except in the case of an Ada 2012
|
|
-- iterator with the expander active. In this case the expander will do
|
|
-- a rewrite of the loop into a while loop. We will then analyze the
|
|
-- loop body when we analyze this while loop.
|
|
|
|
-- We need to do this delay because if the container is for indefinite
|
|
-- types the actual subtype of the components will only be determined
|
|
-- when the cursor declaration is analyzed.
|
|
|
|
-- If the expander is not active then we want to analyze the loop body
|
|
-- now even in the Ada 2012 iterator case, since the rewriting will not
|
|
-- be done. Insert the loop variable in the current scope, if not done
|
|
-- when analysing the iteration scheme. Set its kind properly to detect
|
|
-- improper uses in the loop body.
|
|
|
|
-- In GNATprove mode, we do one of the above depending on the kind of
|
|
-- loop. If it is an iterator over an array, then we do not analyze the
|
|
-- loop now. We will analyze it after it has been rewritten by the
|
|
-- special SPARK expansion which is activated in GNATprove mode. We need
|
|
-- to do this so that other expansions that should occur in GNATprove
|
|
-- mode take into account the specificities of the rewritten loop, in
|
|
-- particular the introduction of a renaming (which needs to be
|
|
-- expanded).
|
|
|
|
-- In other cases in GNATprove mode then we want to analyze the loop
|
|
-- body now, since no rewriting will occur.
|
|
|
|
if Present (Iter)
|
|
and then Present (Iterator_Specification (Iter))
|
|
then
|
|
if GNATprove_Mode
|
|
and then Is_Iterator_Over_Array (Iterator_Specification (Iter))
|
|
then
|
|
null;
|
|
|
|
elsif not Expander_Active then
|
|
declare
|
|
I_Spec : constant Node_Id := Iterator_Specification (Iter);
|
|
Id : constant Entity_Id := Defining_Identifier (I_Spec);
|
|
|
|
begin
|
|
if Scope (Id) /= Current_Scope then
|
|
Enter_Name (Id);
|
|
end if;
|
|
|
|
-- In an element iterator, The loop parameter is a variable if
|
|
-- the domain of iteration (container or array) is a variable.
|
|
|
|
if not Of_Present (I_Spec)
|
|
or else not Is_Variable (Name (I_Spec))
|
|
then
|
|
Set_Ekind (Id, E_Loop_Parameter);
|
|
end if;
|
|
end;
|
|
|
|
Analyze_Statements (Statements (N));
|
|
end if;
|
|
|
|
else
|
|
|
|
-- Pre-Ada2012 for-loops and while loops.
|
|
|
|
Analyze_Statements (Statements (N));
|
|
end if;
|
|
|
|
-- When the iteration scheme of a loop contains attribute 'Loop_Entry,
|
|
-- the loop is transformed into a conditional block. Retrieve the loop.
|
|
|
|
Stmt := N;
|
|
|
|
if Subject_To_Loop_Entry_Attributes (Stmt) then
|
|
Stmt := Find_Loop_In_Conditional_Block (Stmt);
|
|
end if;
|
|
|
|
-- Finish up processing for the loop. We kill all current values, since
|
|
-- in general we don't know if the statements in the loop have been
|
|
-- executed. We could do a bit better than this with a loop that we
|
|
-- know will execute at least once, but it's not worth the trouble and
|
|
-- the front end is not in the business of flow tracing.
|
|
|
|
Process_End_Label (Stmt, 'e', Ent);
|
|
End_Scope;
|
|
Kill_Current_Values;
|
|
|
|
-- Check for infinite loop. Skip check for generated code, since it
|
|
-- justs waste time and makes debugging the routine called harder.
|
|
|
|
-- Note that we have to wait till the body of the loop is fully analyzed
|
|
-- before making this call, since Check_Infinite_Loop_Warning relies on
|
|
-- being able to use semantic visibility information to find references.
|
|
|
|
if Comes_From_Source (Stmt) then
|
|
Check_Infinite_Loop_Warning (Stmt);
|
|
end if;
|
|
|
|
-- Code after loop is unreachable if the loop has no WHILE or FOR and
|
|
-- contains no EXIT statements within the body of the loop.
|
|
|
|
if No (Iter) and then not Has_Exit (Ent) then
|
|
Check_Unreachable_Code (Stmt);
|
|
end if;
|
|
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);
|
|
|
|
-- Remove dimension in all statements
|
|
|
|
Remove_Dimension_In_Statement (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_Node : Node_Id;
|
|
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));
|
|
|
|
-- Skip past pragmas
|
|
|
|
while Nkind (Nxt) = N_Pragma loop
|
|
Nxt := Original_Node (Next (Nxt));
|
|
end loop;
|
|
|
|
-- If a label follows us, then we never have dead code, since
|
|
-- someone could branch to the label, so we just ignore it, unless
|
|
-- we are in formal mode where goto statements are not allowed.
|
|
|
|
if Nkind (Nxt) = N_Label
|
|
and then not Restriction_Check_Required (SPARK_05)
|
|
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_Simple_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_Node := 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
|
|
-- or CodePeer 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 or loses useful
|
|
-- information in the CodePeer tree.
|
|
|
|
-- 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
|
|
and then not CodePeer_Mode
|
|
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 (or error in formal mode)
|
|
|
|
if Restriction_Check_Required (SPARK_05) then
|
|
Check_SPARK_05_Restriction
|
|
("unreachable code is not allowed", Error_Node);
|
|
else
|
|
Error_Msg ("??unreachable code!", Sloc (Error_Node));
|
|
end if;
|
|
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
|
|
-- The original loop is now placed inside a block statement
|
|
-- due to the expansion of attribute 'Loop_Entry. Return as
|
|
-- this is not a "real" block for the purposes of exit
|
|
-- counting.
|
|
|
|
if Nkind (N) = N_Loop_Statement
|
|
and then Subject_To_Loop_Entry_Attributes (N)
|
|
then
|
|
return;
|
|
end if;
|
|
|
|
-- 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;
|
|
|
|
----------------------
|
|
-- Preanalyze_Range --
|
|
----------------------
|
|
|
|
procedure Preanalyze_Range (R_Copy : Node_Id) is
|
|
Save_Analysis : constant Boolean := Full_Analysis;
|
|
Typ : Entity_Id;
|
|
|
|
begin
|
|
Full_Analysis := False;
|
|
Expander_Mode_Save_And_Set (False);
|
|
|
|
Analyze (R_Copy);
|
|
|
|
if Nkind (R_Copy) in N_Subexpr and then 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;
|
|
|
|
-- Subtype mark in iteration scheme
|
|
|
|
if Is_Entity_Name (R_Copy) and then Is_Type (Entity (R_Copy)) then
|
|
null;
|
|
|
|
-- Expression in range, or Ada 2012 iterator
|
|
|
|
elsif Nkind (R_Copy) in N_Subexpr then
|
|
Resolve (R_Copy);
|
|
Typ := Etype (R_Copy);
|
|
|
|
if Is_Discrete_Type (Typ) then
|
|
null;
|
|
|
|
-- Check that the resulting object is an iterable container
|
|
|
|
elsif Has_Aspect (Typ, Aspect_Iterator_Element)
|
|
or else Has_Aspect (Typ, Aspect_Constant_Indexing)
|
|
or else Has_Aspect (Typ, Aspect_Variable_Indexing)
|
|
then
|
|
null;
|
|
|
|
-- The expression may yield an implicit reference to an iterable
|
|
-- container. Insert explicit dereference so that proper type is
|
|
-- visible in the loop.
|
|
|
|
elsif Has_Implicit_Dereference (Etype (R_Copy)) then
|
|
declare
|
|
Disc : Entity_Id;
|
|
|
|
begin
|
|
Disc := First_Discriminant (Typ);
|
|
while Present (Disc) loop
|
|
if Has_Implicit_Dereference (Disc) then
|
|
Build_Explicit_Dereference (R_Copy, Disc);
|
|
exit;
|
|
end if;
|
|
|
|
Next_Discriminant (Disc);
|
|
end loop;
|
|
end;
|
|
|
|
end if;
|
|
end if;
|
|
|
|
Expander_Mode_Restore;
|
|
Full_Analysis := Save_Analysis;
|
|
end Preanalyze_Range;
|
|
|
|
end Sem_Ch5;
|