1849 lines
67 KiB
Ada
1849 lines
67 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S E M _ D I S P --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 1992-2009, 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 Atree; use Atree;
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with Debug; use Debug;
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with Elists; use Elists;
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with Einfo; use Einfo;
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with Exp_Disp; use Exp_Disp;
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with Exp_Util; use Exp_Util;
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with Exp_Ch7; use Exp_Ch7;
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with Exp_Tss; use Exp_Tss;
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with Errout; use Errout;
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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 Output; use Output;
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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_Ch3; use Sem_Ch3;
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with Sem_Ch6; use Sem_Ch6;
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with Sem_Eval; use Sem_Eval;
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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 Snames; use Snames;
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with Sinfo; use Sinfo;
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with Tbuild; use Tbuild;
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with Uintp; use Uintp;
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package body Sem_Disp is
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-----------------------
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-- Local Subprograms --
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-----------------------
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procedure Add_Dispatching_Operation
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(Tagged_Type : Entity_Id;
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New_Op : Entity_Id);
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-- Add New_Op in the list of primitive operations of Tagged_Type
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function Check_Controlling_Type
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(T : Entity_Id;
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Subp : Entity_Id) return Entity_Id;
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-- T is the tagged type of a formal parameter or the result of Subp.
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-- If the subprogram has a controlling parameter or result that matches
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-- the type, then returns the tagged type of that parameter or result
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-- (returning the designated tagged type in the case of an access
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-- parameter); otherwise returns empty.
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-------------------------------
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-- Add_Dispatching_Operation --
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-------------------------------
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procedure Add_Dispatching_Operation
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(Tagged_Type : Entity_Id;
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New_Op : Entity_Id)
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is
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List : constant Elist_Id := Primitive_Operations (Tagged_Type);
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begin
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-- The dispatching operation may already be on the list, if it is the
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-- wrapper for an inherited function of a null extension (see Exp_Ch3
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-- for the construction of function wrappers). The list of primitive
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-- operations must not contain duplicates.
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Append_Unique_Elmt (New_Op, List);
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end Add_Dispatching_Operation;
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-------------------------------
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-- Check_Controlling_Formals --
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-------------------------------
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procedure Check_Controlling_Formals
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(Typ : Entity_Id;
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Subp : Entity_Id)
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is
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Formal : Entity_Id;
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Ctrl_Type : Entity_Id;
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begin
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Formal := First_Formal (Subp);
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while Present (Formal) loop
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Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
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if Present (Ctrl_Type) then
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-- When controlling type is concurrent and declared within a
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-- generic or inside an instance use corresponding record type.
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if Is_Concurrent_Type (Ctrl_Type)
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and then Present (Corresponding_Record_Type (Ctrl_Type))
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then
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Ctrl_Type := Corresponding_Record_Type (Ctrl_Type);
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end if;
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if Ctrl_Type = Typ then
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Set_Is_Controlling_Formal (Formal);
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-- Ada 2005 (AI-231): Anonymous access types that are used in
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-- controlling parameters exclude null because it is necessary
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-- to read the tag to dispatch, and null has no tag.
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if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
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Set_Can_Never_Be_Null (Etype (Formal));
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Set_Is_Known_Non_Null (Etype (Formal));
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end if;
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-- Check that the parameter's nominal subtype statically
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-- matches the first subtype.
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if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
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if not Subtypes_Statically_Match
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(Typ, Designated_Type (Etype (Formal)))
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then
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Error_Msg_N
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("parameter subtype does not match controlling type",
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Formal);
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end if;
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elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) then
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Error_Msg_N
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("parameter subtype does not match controlling type",
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Formal);
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end if;
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if Present (Default_Value (Formal)) then
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-- In Ada 2005, access parameters can have defaults
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if Ekind (Etype (Formal)) = E_Anonymous_Access_Type
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and then Ada_Version < Ada_05
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then
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Error_Msg_N
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("default not allowed for controlling access parameter",
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Default_Value (Formal));
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elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then
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Error_Msg_N
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("default expression must be a tag indeterminate" &
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" function call", Default_Value (Formal));
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end if;
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end if;
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elsif Comes_From_Source (Subp) then
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Error_Msg_N
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("operation can be dispatching in only one type", Subp);
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end if;
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end if;
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Next_Formal (Formal);
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end loop;
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if Ekind (Subp) = E_Function
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or else
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Ekind (Subp) = E_Generic_Function
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then
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Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp);
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if Present (Ctrl_Type) then
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if Ctrl_Type = Typ then
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Set_Has_Controlling_Result (Subp);
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-- Check that result subtype statically matches first subtype
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-- (Ada 2005): Subp may have a controlling access result.
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if Subtypes_Statically_Match (Typ, Etype (Subp))
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or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type
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and then
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Subtypes_Statically_Match
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(Typ, Designated_Type (Etype (Subp))))
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then
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null;
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else
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Error_Msg_N
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("result subtype does not match controlling type", Subp);
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end if;
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elsif Comes_From_Source (Subp) then
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Error_Msg_N
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("operation can be dispatching in only one type", Subp);
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end if;
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end if;
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end if;
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end Check_Controlling_Formals;
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----------------------------
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-- Check_Controlling_Type --
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----------------------------
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function Check_Controlling_Type
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(T : Entity_Id;
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Subp : Entity_Id) return Entity_Id
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is
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Tagged_Type : Entity_Id := Empty;
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begin
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if Is_Tagged_Type (T) then
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if Is_First_Subtype (T) then
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Tagged_Type := T;
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else
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Tagged_Type := Base_Type (T);
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end if;
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elsif Ekind (T) = E_Anonymous_Access_Type
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and then Is_Tagged_Type (Designated_Type (T))
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then
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if Ekind (Designated_Type (T)) /= E_Incomplete_Type then
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if Is_First_Subtype (Designated_Type (T)) then
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Tagged_Type := Designated_Type (T);
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else
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Tagged_Type := Base_Type (Designated_Type (T));
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end if;
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-- Ada 2005: an incomplete type can be tagged. An operation with an
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-- access parameter of the type is dispatching.
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elsif Scope (Designated_Type (T)) = Current_Scope then
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Tagged_Type := Designated_Type (T);
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-- Ada 2005 (AI-50217)
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elsif From_With_Type (Designated_Type (T))
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and then Present (Non_Limited_View (Designated_Type (T)))
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then
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if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then
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Tagged_Type := Non_Limited_View (Designated_Type (T));
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else
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Tagged_Type := Base_Type (Non_Limited_View
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(Designated_Type (T)));
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end if;
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end if;
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end if;
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if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then
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return Empty;
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-- The dispatching type and the primitive operation must be defined in
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-- the same scope, except in the case of internal operations and formal
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-- abstract subprograms.
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elsif ((Scope (Subp) = Scope (Tagged_Type) or else Is_Internal (Subp))
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and then (not Is_Generic_Type (Tagged_Type)
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or else not Comes_From_Source (Subp)))
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or else
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(Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp))
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or else
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(Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration
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and then
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Present (Corresponding_Formal_Spec (Parent (Parent (Subp))))
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and then
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Is_Abstract_Subprogram (Subp))
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then
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return Tagged_Type;
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else
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return Empty;
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end if;
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end Check_Controlling_Type;
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----------------------------
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-- Check_Dispatching_Call --
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----------------------------
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procedure Check_Dispatching_Call (N : Node_Id) is
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Loc : constant Source_Ptr := Sloc (N);
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Actual : Node_Id;
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Formal : Entity_Id;
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Control : Node_Id := Empty;
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Func : Entity_Id;
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Subp_Entity : Entity_Id;
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Indeterm_Ancestor_Call : Boolean := False;
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Indeterm_Ctrl_Type : Entity_Id;
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Static_Tag : Node_Id := Empty;
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-- If a controlling formal has a statically tagged actual, the tag of
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-- this actual is to be used for any tag-indeterminate actual.
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procedure Check_Direct_Call;
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-- In the case when the controlling actual is a class-wide type whose
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-- root type's completion is a task or protected type, the call is in
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-- fact direct. This routine detects the above case and modifies the
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-- call accordingly.
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procedure Check_Dispatching_Context;
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-- If the call is tag-indeterminate and the entity being called is
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-- abstract, verify that the context is a call that will eventually
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-- provide a tag for dispatching, or has provided one already.
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-----------------------
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-- Check_Direct_Call --
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-----------------------
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procedure Check_Direct_Call is
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Typ : Entity_Id := Etype (Control);
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function Is_User_Defined_Equality (Id : Entity_Id) return Boolean;
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-- Determine whether an entity denotes a user-defined equality
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------------------------------
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-- Is_User_Defined_Equality --
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------------------------------
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function Is_User_Defined_Equality (Id : Entity_Id) return Boolean is
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begin
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return
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Ekind (Id) = E_Function
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and then Chars (Id) = Name_Op_Eq
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and then Comes_From_Source (Id)
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-- Internally generated equalities have a full type declaration
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-- as their parent.
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and then Nkind (Parent (Id)) = N_Function_Specification;
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end Is_User_Defined_Equality;
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-- Start of processing for Check_Direct_Call
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begin
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-- Predefined primitives do not receive wrappers since they are built
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-- from scratch for the corresponding record of synchronized types.
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-- Equality is in general predefined, but is excluded from the check
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-- when it is user-defined.
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if Is_Predefined_Dispatching_Operation (Subp_Entity)
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and then not Is_User_Defined_Equality (Subp_Entity)
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then
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return;
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end if;
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if Is_Class_Wide_Type (Typ) then
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Typ := Root_Type (Typ);
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end if;
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if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then
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Typ := Full_View (Typ);
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end if;
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if Is_Concurrent_Type (Typ)
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and then
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Present (Corresponding_Record_Type (Typ))
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then
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Typ := Corresponding_Record_Type (Typ);
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-- The concurrent record's list of primitives should contain a
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-- wrapper for the entity of the call, retrieve it.
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declare
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Prim : Entity_Id;
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Prim_Elmt : Elmt_Id;
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Wrapper_Found : Boolean := False;
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begin
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Prim_Elmt := First_Elmt (Primitive_Operations (Typ));
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while Present (Prim_Elmt) loop
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Prim := Node (Prim_Elmt);
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if Is_Primitive_Wrapper (Prim)
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and then Wrapped_Entity (Prim) = Subp_Entity
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then
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Wrapper_Found := True;
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exit;
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end if;
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Next_Elmt (Prim_Elmt);
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end loop;
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-- A primitive declared between two views should have a
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-- corresponding wrapper.
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pragma Assert (Wrapper_Found);
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-- Modify the call by setting the proper entity
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Set_Entity (Name (N), Prim);
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end;
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end if;
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end Check_Direct_Call;
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-------------------------------
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-- Check_Dispatching_Context --
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-------------------------------
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procedure Check_Dispatching_Context is
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Subp : constant Entity_Id := Entity (Name (N));
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Par : Node_Id;
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begin
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if Is_Abstract_Subprogram (Subp)
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and then No (Controlling_Argument (N))
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then
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if Present (Alias (Subp))
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and then not Is_Abstract_Subprogram (Alias (Subp))
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and then No (DTC_Entity (Subp))
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then
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-- Private overriding of inherited abstract operation, call is
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-- legal.
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Set_Entity (Name (N), Alias (Subp));
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return;
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else
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Par := Parent (N);
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while Present (Par) loop
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if Nkind_In (Par, N_Function_Call,
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N_Procedure_Call_Statement,
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N_Assignment_Statement,
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N_Op_Eq,
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N_Op_Ne)
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and then Is_Tagged_Type (Etype (Subp))
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then
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return;
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elsif Nkind (Par) = N_Qualified_Expression
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or else Nkind (Par) = N_Unchecked_Type_Conversion
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then
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Par := Parent (Par);
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else
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if Ekind (Subp) = E_Function then
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Error_Msg_N
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("call to abstract function must be dispatching", N);
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-- This error can occur for a procedure in the case of a
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-- call to an abstract formal procedure with a statically
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-- tagged operand.
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else
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Error_Msg_N
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("call to abstract procedure must be dispatching",
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N);
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end if;
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return;
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end if;
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end loop;
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end if;
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end if;
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end Check_Dispatching_Context;
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|
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-- Start of processing for Check_Dispatching_Call
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begin
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-- Find a controlling argument, if any
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if Present (Parameter_Associations (N)) then
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Subp_Entity := Entity (Name (N));
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Actual := First_Actual (N);
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Formal := First_Formal (Subp_Entity);
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while Present (Actual) loop
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Control := Find_Controlling_Arg (Actual);
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exit when Present (Control);
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-- Check for the case where the actual is a tag-indeterminate call
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-- whose result type is different than the tagged type associated
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-- with the containing call, but is an ancestor of the type.
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if Is_Controlling_Formal (Formal)
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and then Is_Tag_Indeterminate (Actual)
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and then Base_Type (Etype (Actual)) /= Base_Type (Etype (Formal))
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and then Is_Ancestor (Etype (Actual), Etype (Formal))
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then
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Indeterm_Ancestor_Call := True;
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Indeterm_Ctrl_Type := Etype (Formal);
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-- If the formal is controlling but the actual is not, the type
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-- of the actual is statically known, and may be used as the
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-- controlling tag for some other tag-indeterminate actual.
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elsif Is_Controlling_Formal (Formal)
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and then Is_Entity_Name (Actual)
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and then Is_Tagged_Type (Etype (Actual))
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then
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Static_Tag := Actual;
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end if;
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Next_Actual (Actual);
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Next_Formal (Formal);
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end loop;
|
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|
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-- If the call doesn't have a controlling actual but does have an
|
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-- indeterminate actual that requires dispatching treatment, then an
|
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-- object is needed that will serve as the controlling argument for a
|
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-- dispatching call on the indeterminate actual. This can only occur
|
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-- in the unusual situation of a default actual given by a
|
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-- tag-indeterminate call and where the type of the call is an
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-- ancestor of the type associated with a containing call to an
|
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-- inherited operation (see AI-239).
|
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|
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-- Rather than create an object of the tagged type, which would be
|
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-- problematic for various reasons (default initialization,
|
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-- discriminants), the tag of the containing call's associated tagged
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-- type is directly used to control the dispatching.
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|
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if No (Control)
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and then Indeterm_Ancestor_Call
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and then No (Static_Tag)
|
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then
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Control :=
|
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Make_Attribute_Reference (Loc,
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Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc),
|
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Attribute_Name => Name_Tag);
|
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Analyze (Control);
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end if;
|
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|
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if Present (Control) then
|
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|
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-- Verify that no controlling arguments are statically tagged
|
|
|
|
if Debug_Flag_E then
|
|
Write_Str ("Found Dispatching call");
|
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Write_Int (Int (N));
|
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Write_Eol;
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|
end if;
|
|
|
|
Actual := First_Actual (N);
|
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while Present (Actual) loop
|
|
if Actual /= Control then
|
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|
|
if not Is_Controlling_Actual (Actual) then
|
|
null; -- Can be anything
|
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|
|
elsif Is_Dynamically_Tagged (Actual) then
|
|
null; -- Valid parameter
|
|
|
|
elsif Is_Tag_Indeterminate (Actual) then
|
|
|
|
-- The tag is inherited from the enclosing call (the node
|
|
-- we are currently analyzing). Explicitly expand the
|
|
-- actual, since the previous call to Expand (from
|
|
-- Resolve_Call) had no way of knowing about the required
|
|
-- dispatching.
|
|
|
|
Propagate_Tag (Control, Actual);
|
|
|
|
else
|
|
Error_Msg_N
|
|
("controlling argument is not dynamically tagged",
|
|
Actual);
|
|
return;
|
|
end if;
|
|
end if;
|
|
|
|
Next_Actual (Actual);
|
|
end loop;
|
|
|
|
-- Mark call as a dispatching call
|
|
|
|
Set_Controlling_Argument (N, Control);
|
|
Check_Restriction (No_Dispatching_Calls, N);
|
|
|
|
-- The dispatching call may need to be converted into a direct
|
|
-- call in certain cases.
|
|
|
|
Check_Direct_Call;
|
|
|
|
-- If there is a statically tagged actual and a tag-indeterminate
|
|
-- call to a function of the ancestor (such as that provided by a
|
|
-- default), then treat this as a dispatching call and propagate
|
|
-- the tag to the tag-indeterminate call(s).
|
|
|
|
elsif Present (Static_Tag) and then Indeterm_Ancestor_Call then
|
|
Control :=
|
|
Make_Attribute_Reference (Loc,
|
|
Prefix =>
|
|
New_Occurrence_Of (Etype (Static_Tag), Loc),
|
|
Attribute_Name => Name_Tag);
|
|
|
|
Analyze (Control);
|
|
|
|
Actual := First_Actual (N);
|
|
Formal := First_Formal (Subp_Entity);
|
|
while Present (Actual) loop
|
|
if Is_Tag_Indeterminate (Actual)
|
|
and then Is_Controlling_Formal (Formal)
|
|
then
|
|
Propagate_Tag (Control, Actual);
|
|
end if;
|
|
|
|
Next_Actual (Actual);
|
|
Next_Formal (Formal);
|
|
end loop;
|
|
|
|
Check_Dispatching_Context;
|
|
|
|
else
|
|
-- The call is not dispatching, so check that there aren't any
|
|
-- tag-indeterminate abstract calls left.
|
|
|
|
Actual := First_Actual (N);
|
|
while Present (Actual) loop
|
|
if Is_Tag_Indeterminate (Actual) then
|
|
|
|
-- Function call case
|
|
|
|
if Nkind (Original_Node (Actual)) = N_Function_Call then
|
|
Func := Entity (Name (Original_Node (Actual)));
|
|
|
|
-- If the actual is an attribute then it can't be abstract
|
|
-- (the only current case of a tag-indeterminate attribute
|
|
-- is the stream Input attribute).
|
|
|
|
elsif
|
|
Nkind (Original_Node (Actual)) = N_Attribute_Reference
|
|
then
|
|
Func := Empty;
|
|
|
|
-- Only other possibility is a qualified expression whose
|
|
-- constituent expression is itself a call.
|
|
|
|
else
|
|
Func :=
|
|
Entity (Name
|
|
(Original_Node
|
|
(Expression (Original_Node (Actual)))));
|
|
end if;
|
|
|
|
if Present (Func) and then Is_Abstract_Subprogram (Func) then
|
|
Error_Msg_N (
|
|
"call to abstract function must be dispatching", N);
|
|
end if;
|
|
end if;
|
|
|
|
Next_Actual (Actual);
|
|
end loop;
|
|
|
|
Check_Dispatching_Context;
|
|
end if;
|
|
|
|
else
|
|
-- If dispatching on result, the enclosing call, if any, will
|
|
-- determine the controlling argument. Otherwise this is the
|
|
-- primitive operation of the root type.
|
|
|
|
Check_Dispatching_Context;
|
|
end if;
|
|
end Check_Dispatching_Call;
|
|
|
|
---------------------------------
|
|
-- Check_Dispatching_Operation --
|
|
---------------------------------
|
|
|
|
procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id) is
|
|
Tagged_Type : Entity_Id;
|
|
Has_Dispatching_Parent : Boolean := False;
|
|
Body_Is_Last_Primitive : Boolean := False;
|
|
|
|
begin
|
|
if Ekind (Subp) /= E_Procedure and then Ekind (Subp) /= E_Function then
|
|
return;
|
|
end if;
|
|
|
|
Set_Is_Dispatching_Operation (Subp, False);
|
|
Tagged_Type := Find_Dispatching_Type (Subp);
|
|
|
|
-- Ada 2005 (AI-345)
|
|
|
|
if Ada_Version = Ada_05
|
|
and then Present (Tagged_Type)
|
|
and then Is_Concurrent_Type (Tagged_Type)
|
|
then
|
|
-- Protect the frontend against previously detected errors
|
|
|
|
if No (Corresponding_Record_Type (Tagged_Type)) then
|
|
return;
|
|
end if;
|
|
|
|
Tagged_Type := Corresponding_Record_Type (Tagged_Type);
|
|
end if;
|
|
|
|
-- (AI-345): The task body procedure is not a primitive of the tagged
|
|
-- type
|
|
|
|
if Present (Tagged_Type)
|
|
and then Is_Concurrent_Record_Type (Tagged_Type)
|
|
and then Present (Corresponding_Concurrent_Type (Tagged_Type))
|
|
and then Is_Task_Type (Corresponding_Concurrent_Type (Tagged_Type))
|
|
and then Subp = Get_Task_Body_Procedure
|
|
(Corresponding_Concurrent_Type (Tagged_Type))
|
|
then
|
|
return;
|
|
end if;
|
|
|
|
-- If Subp is derived from a dispatching operation then it should
|
|
-- always be treated as dispatching. In this case various checks
|
|
-- below will be bypassed. Makes sure that late declarations for
|
|
-- inherited private subprograms are treated as dispatching, even
|
|
-- if the associated tagged type is already frozen.
|
|
|
|
Has_Dispatching_Parent :=
|
|
Present (Alias (Subp))
|
|
and then Is_Dispatching_Operation (Alias (Subp));
|
|
|
|
if No (Tagged_Type) then
|
|
|
|
-- Ada 2005 (AI-251): Check that Subp is not a primitive associated
|
|
-- with an abstract interface type unless the interface acts as a
|
|
-- parent type in a derivation. If the interface type is a formal
|
|
-- type then the operation is not primitive and therefore legal.
|
|
|
|
declare
|
|
E : Entity_Id;
|
|
Typ : Entity_Id;
|
|
|
|
begin
|
|
E := First_Entity (Subp);
|
|
while Present (E) loop
|
|
|
|
-- For an access parameter, check designated type
|
|
|
|
if Ekind (Etype (E)) = E_Anonymous_Access_Type then
|
|
Typ := Designated_Type (Etype (E));
|
|
else
|
|
Typ := Etype (E);
|
|
end if;
|
|
|
|
if Comes_From_Source (Subp)
|
|
and then Is_Interface (Typ)
|
|
and then not Is_Class_Wide_Type (Typ)
|
|
and then not Is_Derived_Type (Typ)
|
|
and then not Is_Generic_Type (Typ)
|
|
and then not In_Instance
|
|
then
|
|
Error_Msg_N ("?declaration of& is too late!", Subp);
|
|
Error_Msg_NE
|
|
("\spec should appear immediately after declaration of &!",
|
|
Subp, Typ);
|
|
exit;
|
|
end if;
|
|
|
|
Next_Entity (E);
|
|
end loop;
|
|
|
|
-- In case of functions check also the result type
|
|
|
|
if Ekind (Subp) = E_Function then
|
|
if Is_Access_Type (Etype (Subp)) then
|
|
Typ := Designated_Type (Etype (Subp));
|
|
else
|
|
Typ := Etype (Subp);
|
|
end if;
|
|
|
|
if not Is_Class_Wide_Type (Typ)
|
|
and then Is_Interface (Typ)
|
|
and then not Is_Derived_Type (Typ)
|
|
then
|
|
Error_Msg_N ("?declaration of& is too late!", Subp);
|
|
Error_Msg_NE
|
|
("\spec should appear immediately after declaration of &!",
|
|
Subp, Typ);
|
|
end if;
|
|
end if;
|
|
end;
|
|
|
|
return;
|
|
|
|
-- The subprograms build internally after the freezing point (such as
|
|
-- init procs, interface thunks, type support subprograms, and Offset
|
|
-- to top functions for accessing interface components in variable
|
|
-- size tagged types) are not primitives.
|
|
|
|
elsif Is_Frozen (Tagged_Type)
|
|
and then not Comes_From_Source (Subp)
|
|
and then not Has_Dispatching_Parent
|
|
then
|
|
-- Complete decoration if internally built subprograms that override
|
|
-- a dispatching primitive. These entities correspond with the
|
|
-- following cases:
|
|
|
|
-- 1. Ada 2005 (AI-391): Wrapper functions built by the expander
|
|
-- to override functions of nonabstract null extensions. These
|
|
-- primitives were added to the list of primitives of the tagged
|
|
-- type by Make_Controlling_Function_Wrappers. However, attribute
|
|
-- Is_Dispatching_Operation must be set to true.
|
|
|
|
-- 2. Subprograms associated with stream attributes (built by
|
|
-- New_Stream_Subprogram)
|
|
|
|
if Present (Old_Subp)
|
|
and then Is_Overriding_Operation (Subp)
|
|
and then Is_Dispatching_Operation (Old_Subp)
|
|
then
|
|
pragma Assert
|
|
((Ekind (Subp) = E_Function
|
|
and then Is_Dispatching_Operation (Old_Subp)
|
|
and then Is_Null_Extension (Base_Type (Etype (Subp))))
|
|
or else Get_TSS_Name (Subp) = TSS_Stream_Read
|
|
or else Get_TSS_Name (Subp) = TSS_Stream_Write);
|
|
|
|
Set_Is_Dispatching_Operation (Subp);
|
|
end if;
|
|
|
|
return;
|
|
|
|
-- The operation may be a child unit, whose scope is the defining
|
|
-- package, but which is not a primitive operation of the type.
|
|
|
|
elsif Is_Child_Unit (Subp) then
|
|
return;
|
|
|
|
-- If the subprogram is not defined in a package spec, the only case
|
|
-- where it can be a dispatching op is when it overrides an operation
|
|
-- before the freezing point of the type.
|
|
|
|
elsif ((not Is_Package_Or_Generic_Package (Scope (Subp)))
|
|
or else In_Package_Body (Scope (Subp)))
|
|
and then not Has_Dispatching_Parent
|
|
then
|
|
if not Comes_From_Source (Subp)
|
|
or else (Present (Old_Subp) and then not Is_Frozen (Tagged_Type))
|
|
then
|
|
null;
|
|
|
|
-- If the type is already frozen, the overriding is not allowed
|
|
-- except when Old_Subp is not a dispatching operation (which can
|
|
-- occur when Old_Subp was inherited by an untagged type). However,
|
|
-- a body with no previous spec freezes the type *after* its
|
|
-- declaration, and therefore is a legal overriding (unless the type
|
|
-- has already been frozen). Only the first such body is legal.
|
|
|
|
elsif Present (Old_Subp)
|
|
and then Is_Dispatching_Operation (Old_Subp)
|
|
then
|
|
if Comes_From_Source (Subp)
|
|
and then
|
|
(Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body
|
|
or else Nkind (Unit_Declaration_Node (Subp)) in N_Body_Stub)
|
|
then
|
|
declare
|
|
Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
|
|
Decl_Item : Node_Id;
|
|
|
|
begin
|
|
-- ??? The checks here for whether the type has been
|
|
-- frozen prior to the new body are not complete. It's
|
|
-- not simple to check frozenness at this point since
|
|
-- the body has already caused the type to be prematurely
|
|
-- frozen in Analyze_Declarations, but we're forced to
|
|
-- recheck this here because of the odd rule interpretation
|
|
-- that allows the overriding if the type wasn't frozen
|
|
-- prior to the body. The freezing action should probably
|
|
-- be delayed until after the spec is seen, but that's
|
|
-- a tricky change to the delicate freezing code.
|
|
|
|
-- Look at each declaration following the type up until the
|
|
-- new subprogram body. If any of the declarations is a body
|
|
-- then the type has been frozen already so the overriding
|
|
-- primitive is illegal.
|
|
|
|
Decl_Item := Next (Parent (Tagged_Type));
|
|
while Present (Decl_Item)
|
|
and then (Decl_Item /= Subp_Body)
|
|
loop
|
|
if Comes_From_Source (Decl_Item)
|
|
and then (Nkind (Decl_Item) in N_Proper_Body
|
|
or else Nkind (Decl_Item) in N_Body_Stub)
|
|
then
|
|
Error_Msg_N ("overriding of& is too late!", Subp);
|
|
Error_Msg_N
|
|
("\spec should appear immediately after the type!",
|
|
Subp);
|
|
exit;
|
|
end if;
|
|
|
|
Next (Decl_Item);
|
|
end loop;
|
|
|
|
-- If the subprogram doesn't follow in the list of
|
|
-- declarations including the type then the type has
|
|
-- definitely been frozen already and the body is illegal.
|
|
|
|
if No (Decl_Item) then
|
|
Error_Msg_N ("overriding of& is too late!", Subp);
|
|
Error_Msg_N
|
|
("\spec should appear immediately after the type!",
|
|
Subp);
|
|
|
|
elsif Is_Frozen (Subp) then
|
|
|
|
-- The subprogram body declares a primitive operation.
|
|
-- if the subprogram is already frozen, we must update
|
|
-- its dispatching information explicitly here. The
|
|
-- information is taken from the overridden subprogram.
|
|
-- We must also generate a cross-reference entry because
|
|
-- references to other primitives were already created
|
|
-- when type was frozen.
|
|
|
|
Body_Is_Last_Primitive := True;
|
|
|
|
if Present (DTC_Entity (Old_Subp)) then
|
|
Set_DTC_Entity (Subp, DTC_Entity (Old_Subp));
|
|
Set_DT_Position (Subp, DT_Position (Old_Subp));
|
|
|
|
if not Restriction_Active (No_Dispatching_Calls) then
|
|
if Building_Static_DT (Tagged_Type) then
|
|
|
|
-- If the static dispatch table has not been
|
|
-- built then there is nothing else to do now;
|
|
-- otherwise we notify that we cannot build the
|
|
-- static dispatch table.
|
|
|
|
if Has_Dispatch_Table (Tagged_Type) then
|
|
Error_Msg_N
|
|
("overriding of& is too late for building" &
|
|
" static dispatch tables!", Subp);
|
|
Error_Msg_N
|
|
("\spec should appear immediately after" &
|
|
" the type!", Subp);
|
|
end if;
|
|
|
|
else
|
|
Insert_Actions_After (Subp_Body,
|
|
Register_Primitive (Sloc (Subp_Body),
|
|
Prim => Subp));
|
|
end if;
|
|
|
|
-- Indicate that this is an overriding operation,
|
|
-- and replace the overriden entry in the list of
|
|
-- primitive operations, which is used for xref
|
|
-- generation subsequently.
|
|
|
|
Generate_Reference (Tagged_Type, Subp, 'P', False);
|
|
Override_Dispatching_Operation
|
|
(Tagged_Type, Old_Subp, Subp);
|
|
end if;
|
|
end if;
|
|
end if;
|
|
end;
|
|
|
|
else
|
|
Error_Msg_N ("overriding of& is too late!", Subp);
|
|
Error_Msg_N
|
|
("\subprogram spec should appear immediately after the type!",
|
|
Subp);
|
|
end if;
|
|
|
|
-- If the type is not frozen yet and we are not in the overriding
|
|
-- case it looks suspiciously like an attempt to define a primitive
|
|
-- operation, which requires the declaration to be in a package spec
|
|
-- (3.2.3(6)).
|
|
|
|
elsif not Is_Frozen (Tagged_Type) then
|
|
Error_Msg_N
|
|
("?not dispatching (must be defined in a package spec)", Subp);
|
|
return;
|
|
|
|
-- When the type is frozen, it is legitimate to define a new
|
|
-- non-primitive operation.
|
|
|
|
else
|
|
return;
|
|
end if;
|
|
|
|
-- Now, we are sure that the scope is a package spec. If the subprogram
|
|
-- is declared after the freezing point of the type that's an error
|
|
|
|
elsif Is_Frozen (Tagged_Type) and then not Has_Dispatching_Parent then
|
|
Error_Msg_N ("this primitive operation is declared too late", Subp);
|
|
Error_Msg_NE
|
|
("?no primitive operations for& after this line",
|
|
Freeze_Node (Tagged_Type),
|
|
Tagged_Type);
|
|
return;
|
|
end if;
|
|
|
|
Check_Controlling_Formals (Tagged_Type, Subp);
|
|
|
|
-- Now it should be a correct primitive operation, put it in the list
|
|
|
|
if Present (Old_Subp) then
|
|
|
|
-- If the type has interfaces we complete this check after we set
|
|
-- attribute Is_Dispatching_Operation.
|
|
|
|
Check_Subtype_Conformant (Subp, Old_Subp);
|
|
|
|
if (Chars (Subp) = Name_Initialize
|
|
or else Chars (Subp) = Name_Adjust
|
|
or else Chars (Subp) = Name_Finalize)
|
|
and then Is_Controlled (Tagged_Type)
|
|
and then not Is_Visibly_Controlled (Tagged_Type)
|
|
then
|
|
Set_Is_Overriding_Operation (Subp, False);
|
|
|
|
-- If the subprogram specification carries an overriding
|
|
-- indicator, no need for the warning: it is either redundant,
|
|
-- or else an error will be reported.
|
|
|
|
if Nkind (Parent (Subp)) = N_Procedure_Specification
|
|
and then
|
|
(Must_Override (Parent (Subp))
|
|
or else Must_Not_Override (Parent (Subp)))
|
|
then
|
|
null;
|
|
|
|
-- Here we need the warning
|
|
|
|
else
|
|
Error_Msg_NE
|
|
("operation does not override inherited&?", Subp, Subp);
|
|
end if;
|
|
|
|
else
|
|
Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp);
|
|
Set_Is_Overriding_Operation (Subp);
|
|
|
|
-- Ada 2005 (AI-251): In case of late overriding of a primitive
|
|
-- that covers abstract interface subprograms we must register it
|
|
-- in all the secondary dispatch tables associated with abstract
|
|
-- interfaces. We do this now only if not building static tables.
|
|
-- Otherwise the patch code is emitted after those tables are
|
|
-- built, to prevent access_before_elaboration in gigi.
|
|
|
|
if Body_Is_Last_Primitive then
|
|
declare
|
|
Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
|
|
Elmt : Elmt_Id;
|
|
Prim : Node_Id;
|
|
|
|
begin
|
|
Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
|
|
while Present (Elmt) loop
|
|
Prim := Node (Elmt);
|
|
|
|
if Present (Alias (Prim))
|
|
and then Present (Interface_Alias (Prim))
|
|
and then Alias (Prim) = Subp
|
|
and then not Building_Static_DT (Tagged_Type)
|
|
then
|
|
Insert_Actions_After (Subp_Body,
|
|
Register_Primitive (Sloc (Subp_Body), Prim => Prim));
|
|
end if;
|
|
|
|
Next_Elmt (Elmt);
|
|
end loop;
|
|
|
|
-- Redisplay the contents of the updated dispatch table
|
|
|
|
if Debug_Flag_ZZ then
|
|
Write_Str ("Late overriding: ");
|
|
Write_DT (Tagged_Type);
|
|
end if;
|
|
end;
|
|
end if;
|
|
end if;
|
|
|
|
-- If no old subprogram, then we add this as a dispatching operation,
|
|
-- but we avoid doing this if an error was posted, to prevent annoying
|
|
-- cascaded errors.
|
|
|
|
elsif not Error_Posted (Subp) then
|
|
Add_Dispatching_Operation (Tagged_Type, Subp);
|
|
end if;
|
|
|
|
Set_Is_Dispatching_Operation (Subp, True);
|
|
|
|
-- Ada 2005 (AI-251): If the type implements interfaces we must check
|
|
-- subtype conformance against all the interfaces covered by this
|
|
-- primitive.
|
|
|
|
if Present (Old_Subp)
|
|
and then Has_Interfaces (Tagged_Type)
|
|
then
|
|
declare
|
|
Ifaces_List : Elist_Id;
|
|
Iface_Elmt : Elmt_Id;
|
|
Iface_Prim_Elmt : Elmt_Id;
|
|
Iface_Prim : Entity_Id;
|
|
Ret_Typ : Entity_Id;
|
|
|
|
begin
|
|
Collect_Interfaces (Tagged_Type, Ifaces_List);
|
|
|
|
Iface_Elmt := First_Elmt (Ifaces_List);
|
|
while Present (Iface_Elmt) loop
|
|
if not Is_Ancestor (Node (Iface_Elmt), Tagged_Type) then
|
|
Iface_Prim_Elmt :=
|
|
First_Elmt (Primitive_Operations (Node (Iface_Elmt)));
|
|
while Present (Iface_Prim_Elmt) loop
|
|
Iface_Prim := Node (Iface_Prim_Elmt);
|
|
|
|
if Is_Interface_Conformant
|
|
(Tagged_Type, Iface_Prim, Subp)
|
|
then
|
|
-- Handle procedures, functions whose return type
|
|
-- matches, or functions not returning interfaces
|
|
|
|
if Ekind (Subp) = E_Procedure
|
|
or else Etype (Iface_Prim) = Etype (Subp)
|
|
or else not Is_Interface (Etype (Iface_Prim))
|
|
then
|
|
Check_Subtype_Conformant
|
|
(New_Id => Subp,
|
|
Old_Id => Iface_Prim,
|
|
Err_Loc => Subp,
|
|
Skip_Controlling_Formals => True);
|
|
|
|
-- Handle functions returning interfaces
|
|
|
|
elsif Implements_Interface
|
|
(Etype (Subp), Etype (Iface_Prim))
|
|
then
|
|
-- Temporarily force both entities to return the
|
|
-- same type. Required because Subtype_Conformant
|
|
-- does not handle this case.
|
|
|
|
Ret_Typ := Etype (Iface_Prim);
|
|
Set_Etype (Iface_Prim, Etype (Subp));
|
|
|
|
Check_Subtype_Conformant
|
|
(New_Id => Subp,
|
|
Old_Id => Iface_Prim,
|
|
Err_Loc => Subp,
|
|
Skip_Controlling_Formals => True);
|
|
|
|
Set_Etype (Iface_Prim, Ret_Typ);
|
|
end if;
|
|
end if;
|
|
|
|
Next_Elmt (Iface_Prim_Elmt);
|
|
end loop;
|
|
end if;
|
|
|
|
Next_Elmt (Iface_Elmt);
|
|
end loop;
|
|
end;
|
|
end if;
|
|
|
|
if not Body_Is_Last_Primitive then
|
|
Set_DT_Position (Subp, No_Uint);
|
|
|
|
elsif Has_Controlled_Component (Tagged_Type)
|
|
and then
|
|
(Chars (Subp) = Name_Initialize
|
|
or else
|
|
Chars (Subp) = Name_Adjust
|
|
or else
|
|
Chars (Subp) = Name_Finalize)
|
|
then
|
|
declare
|
|
F_Node : constant Node_Id := Freeze_Node (Tagged_Type);
|
|
Decl : Node_Id;
|
|
Old_P : Entity_Id;
|
|
Old_Bod : Node_Id;
|
|
Old_Spec : Entity_Id;
|
|
|
|
C_Names : constant array (1 .. 3) of Name_Id :=
|
|
(Name_Initialize,
|
|
Name_Adjust,
|
|
Name_Finalize);
|
|
|
|
D_Names : constant array (1 .. 3) of TSS_Name_Type :=
|
|
(TSS_Deep_Initialize,
|
|
TSS_Deep_Adjust,
|
|
TSS_Deep_Finalize);
|
|
|
|
begin
|
|
-- Remove previous controlled function which was constructed and
|
|
-- analyzed when the type was frozen. This requires removing the
|
|
-- body of the redefined primitive, as well as its specification
|
|
-- if needed (there is no spec created for Deep_Initialize, see
|
|
-- exp_ch3.adb). We must also dismantle the exception information
|
|
-- that may have been generated for it when front end zero-cost
|
|
-- tables are enabled.
|
|
|
|
for J in D_Names'Range loop
|
|
Old_P := TSS (Tagged_Type, D_Names (J));
|
|
|
|
if Present (Old_P)
|
|
and then Chars (Subp) = C_Names (J)
|
|
then
|
|
Old_Bod := Unit_Declaration_Node (Old_P);
|
|
Remove (Old_Bod);
|
|
Set_Is_Eliminated (Old_P);
|
|
Set_Scope (Old_P, Scope (Current_Scope));
|
|
|
|
if Nkind (Old_Bod) = N_Subprogram_Body
|
|
and then Present (Corresponding_Spec (Old_Bod))
|
|
then
|
|
Old_Spec := Corresponding_Spec (Old_Bod);
|
|
Set_Has_Completion (Old_Spec, False);
|
|
end if;
|
|
end if;
|
|
end loop;
|
|
|
|
Build_Late_Proc (Tagged_Type, Chars (Subp));
|
|
|
|
-- The new operation is added to the actions of the freeze node
|
|
-- for the type, but this node has already been analyzed, so we
|
|
-- must retrieve and analyze explicitly the new body.
|
|
|
|
if Present (F_Node)
|
|
and then Present (Actions (F_Node))
|
|
then
|
|
Decl := Last (Actions (F_Node));
|
|
Analyze (Decl);
|
|
end if;
|
|
end;
|
|
end if;
|
|
end Check_Dispatching_Operation;
|
|
|
|
------------------------------------------
|
|
-- Check_Operation_From_Incomplete_Type --
|
|
------------------------------------------
|
|
|
|
procedure Check_Operation_From_Incomplete_Type
|
|
(Subp : Entity_Id;
|
|
Typ : Entity_Id)
|
|
is
|
|
Full : constant Entity_Id := Full_View (Typ);
|
|
Parent_Typ : constant Entity_Id := Etype (Full);
|
|
Old_Prim : constant Elist_Id := Primitive_Operations (Parent_Typ);
|
|
New_Prim : constant Elist_Id := Primitive_Operations (Full);
|
|
Op1, Op2 : Elmt_Id;
|
|
Prev : Elmt_Id := No_Elmt;
|
|
|
|
function Derives_From (Proc : Entity_Id) return Boolean;
|
|
-- Check that Subp has the signature of an operation derived from Proc.
|
|
-- Subp has an access parameter that designates Typ.
|
|
|
|
------------------
|
|
-- Derives_From --
|
|
------------------
|
|
|
|
function Derives_From (Proc : Entity_Id) return Boolean is
|
|
F1, F2 : Entity_Id;
|
|
|
|
begin
|
|
if Chars (Proc) /= Chars (Subp) then
|
|
return False;
|
|
end if;
|
|
|
|
F1 := First_Formal (Proc);
|
|
F2 := First_Formal (Subp);
|
|
while Present (F1) and then Present (F2) loop
|
|
if Ekind (Etype (F1)) = E_Anonymous_Access_Type then
|
|
if Ekind (Etype (F2)) /= E_Anonymous_Access_Type then
|
|
return False;
|
|
elsif Designated_Type (Etype (F1)) = Parent_Typ
|
|
and then Designated_Type (Etype (F2)) /= Full
|
|
then
|
|
return False;
|
|
end if;
|
|
|
|
elsif Ekind (Etype (F2)) = E_Anonymous_Access_Type then
|
|
return False;
|
|
|
|
elsif Etype (F1) /= Etype (F2) then
|
|
return False;
|
|
end if;
|
|
|
|
Next_Formal (F1);
|
|
Next_Formal (F2);
|
|
end loop;
|
|
|
|
return No (F1) and then No (F2);
|
|
end Derives_From;
|
|
|
|
-- Start of processing for Check_Operation_From_Incomplete_Type
|
|
|
|
begin
|
|
-- The operation may override an inherited one, or may be a new one
|
|
-- altogether. The inherited operation will have been hidden by the
|
|
-- current one at the point of the type derivation, so it does not
|
|
-- appear in the list of primitive operations of the type. We have to
|
|
-- find the proper place of insertion in the list of primitive opera-
|
|
-- tions by iterating over the list for the parent type.
|
|
|
|
Op1 := First_Elmt (Old_Prim);
|
|
Op2 := First_Elmt (New_Prim);
|
|
while Present (Op1) and then Present (Op2) loop
|
|
if Derives_From (Node (Op1)) then
|
|
if No (Prev) then
|
|
|
|
-- Avoid adding it to the list of primitives if already there!
|
|
|
|
if Node (Op2) /= Subp then
|
|
Prepend_Elmt (Subp, New_Prim);
|
|
end if;
|
|
|
|
else
|
|
Insert_Elmt_After (Subp, Prev);
|
|
end if;
|
|
|
|
return;
|
|
end if;
|
|
|
|
Prev := Op2;
|
|
Next_Elmt (Op1);
|
|
Next_Elmt (Op2);
|
|
end loop;
|
|
|
|
-- Operation is a new primitive
|
|
|
|
Append_Elmt (Subp, New_Prim);
|
|
end Check_Operation_From_Incomplete_Type;
|
|
|
|
---------------------------------------
|
|
-- Check_Operation_From_Private_View --
|
|
---------------------------------------
|
|
|
|
procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id) is
|
|
Tagged_Type : Entity_Id;
|
|
|
|
begin
|
|
if Is_Dispatching_Operation (Alias (Subp)) then
|
|
Set_Scope (Subp, Current_Scope);
|
|
Tagged_Type := Find_Dispatching_Type (Subp);
|
|
|
|
-- Add Old_Subp to primitive operations if not already present
|
|
|
|
if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then
|
|
Append_Unique_Elmt (Old_Subp, Primitive_Operations (Tagged_Type));
|
|
|
|
-- If Old_Subp isn't already marked as dispatching then
|
|
-- this is the case of an operation of an untagged private
|
|
-- type fulfilled by a tagged type that overrides an
|
|
-- inherited dispatching operation, so we set the necessary
|
|
-- dispatching attributes here.
|
|
|
|
if not Is_Dispatching_Operation (Old_Subp) then
|
|
|
|
-- If the untagged type has no discriminants, and the full
|
|
-- view is constrained, there will be a spurious mismatch
|
|
-- of subtypes on the controlling arguments, because the tagged
|
|
-- type is the internal base type introduced in the derivation.
|
|
-- Use the original type to verify conformance, rather than the
|
|
-- base type.
|
|
|
|
if not Comes_From_Source (Tagged_Type)
|
|
and then Has_Discriminants (Tagged_Type)
|
|
then
|
|
declare
|
|
Formal : Entity_Id;
|
|
|
|
begin
|
|
Formal := First_Formal (Old_Subp);
|
|
while Present (Formal) loop
|
|
if Tagged_Type = Base_Type (Etype (Formal)) then
|
|
Tagged_Type := Etype (Formal);
|
|
end if;
|
|
|
|
Next_Formal (Formal);
|
|
end loop;
|
|
end;
|
|
|
|
if Tagged_Type = Base_Type (Etype (Old_Subp)) then
|
|
Tagged_Type := Etype (Old_Subp);
|
|
end if;
|
|
end if;
|
|
|
|
Check_Controlling_Formals (Tagged_Type, Old_Subp);
|
|
Set_Is_Dispatching_Operation (Old_Subp, True);
|
|
Set_DT_Position (Old_Subp, No_Uint);
|
|
end if;
|
|
|
|
-- If the old subprogram is an explicit renaming of some other
|
|
-- entity, it is not overridden by the inherited subprogram.
|
|
-- Otherwise, update its alias and other attributes.
|
|
|
|
if Present (Alias (Old_Subp))
|
|
and then Nkind (Unit_Declaration_Node (Old_Subp)) /=
|
|
N_Subprogram_Renaming_Declaration
|
|
then
|
|
Set_Alias (Old_Subp, Alias (Subp));
|
|
|
|
-- The derived subprogram should inherit the abstractness
|
|
-- of the parent subprogram (except in the case of a function
|
|
-- returning the type). This sets the abstractness properly
|
|
-- for cases where a private extension may have inherited
|
|
-- an abstract operation, but the full type is derived from
|
|
-- a descendant type and inherits a nonabstract version.
|
|
|
|
if Etype (Subp) /= Tagged_Type then
|
|
Set_Is_Abstract_Subprogram
|
|
(Old_Subp, Is_Abstract_Subprogram (Alias (Subp)));
|
|
end if;
|
|
end if;
|
|
end if;
|
|
end if;
|
|
end Check_Operation_From_Private_View;
|
|
|
|
--------------------------
|
|
-- Find_Controlling_Arg --
|
|
--------------------------
|
|
|
|
function Find_Controlling_Arg (N : Node_Id) return Node_Id is
|
|
Orig_Node : constant Node_Id := Original_Node (N);
|
|
Typ : Entity_Id;
|
|
|
|
begin
|
|
if Nkind (Orig_Node) = N_Qualified_Expression then
|
|
return Find_Controlling_Arg (Expression (Orig_Node));
|
|
end if;
|
|
|
|
-- Dispatching on result case. If expansion is disabled, the node still
|
|
-- has the structure of a function call. However, if the function name
|
|
-- is an operator and the call was given in infix form, the original
|
|
-- node has no controlling result and we must examine the current node.
|
|
|
|
if Nkind (N) = N_Function_Call
|
|
and then Present (Controlling_Argument (N))
|
|
and then Has_Controlling_Result (Entity (Name (N)))
|
|
then
|
|
return Controlling_Argument (N);
|
|
|
|
-- If expansion is enabled, the call may have been transformed into
|
|
-- an indirect call, and we need to recover the original node.
|
|
|
|
elsif Nkind (Orig_Node) = N_Function_Call
|
|
and then Present (Controlling_Argument (Orig_Node))
|
|
and then Has_Controlling_Result (Entity (Name (Orig_Node)))
|
|
then
|
|
return Controlling_Argument (Orig_Node);
|
|
|
|
-- Normal case
|
|
|
|
elsif Is_Controlling_Actual (N)
|
|
or else
|
|
(Nkind (Parent (N)) = N_Qualified_Expression
|
|
and then Is_Controlling_Actual (Parent (N)))
|
|
then
|
|
Typ := Etype (N);
|
|
|
|
if Is_Access_Type (Typ) then
|
|
|
|
-- In the case of an Access attribute, use the type of the prefix,
|
|
-- since in the case of an actual for an access parameter, the
|
|
-- attribute's type may be of a specific designated type, even
|
|
-- though the prefix type is class-wide.
|
|
|
|
if Nkind (N) = N_Attribute_Reference then
|
|
Typ := Etype (Prefix (N));
|
|
|
|
-- An allocator is dispatching if the type of qualified expression
|
|
-- is class_wide, in which case this is the controlling type.
|
|
|
|
elsif Nkind (Orig_Node) = N_Allocator
|
|
and then Nkind (Expression (Orig_Node)) = N_Qualified_Expression
|
|
then
|
|
Typ := Etype (Expression (Orig_Node));
|
|
else
|
|
Typ := Designated_Type (Typ);
|
|
end if;
|
|
end if;
|
|
|
|
if Is_Class_Wide_Type (Typ)
|
|
or else
|
|
(Nkind (Parent (N)) = N_Qualified_Expression
|
|
and then Is_Access_Type (Etype (N))
|
|
and then Is_Class_Wide_Type (Designated_Type (Etype (N))))
|
|
then
|
|
return N;
|
|
end if;
|
|
end if;
|
|
|
|
return Empty;
|
|
end Find_Controlling_Arg;
|
|
|
|
---------------------------
|
|
-- Find_Dispatching_Type --
|
|
---------------------------
|
|
|
|
function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id is
|
|
A_Formal : Entity_Id;
|
|
Formal : Entity_Id;
|
|
Ctrl_Type : Entity_Id;
|
|
|
|
begin
|
|
if Present (DTC_Entity (Subp)) then
|
|
return Scope (DTC_Entity (Subp));
|
|
|
|
-- For subprograms internally generated by derivations of tagged types
|
|
-- use the alias subprogram as a reference to locate the dispatching
|
|
-- type of Subp
|
|
|
|
elsif not Comes_From_Source (Subp)
|
|
and then Present (Alias (Subp))
|
|
and then Is_Dispatching_Operation (Alias (Subp))
|
|
then
|
|
if Ekind (Alias (Subp)) = E_Function
|
|
and then Has_Controlling_Result (Alias (Subp))
|
|
then
|
|
return Check_Controlling_Type (Etype (Subp), Subp);
|
|
|
|
else
|
|
Formal := First_Formal (Subp);
|
|
A_Formal := First_Formal (Alias (Subp));
|
|
while Present (A_Formal) loop
|
|
if Is_Controlling_Formal (A_Formal) then
|
|
return Check_Controlling_Type (Etype (Formal), Subp);
|
|
end if;
|
|
|
|
Next_Formal (Formal);
|
|
Next_Formal (A_Formal);
|
|
end loop;
|
|
|
|
pragma Assert (False);
|
|
return Empty;
|
|
end if;
|
|
|
|
-- General case
|
|
|
|
else
|
|
Formal := First_Formal (Subp);
|
|
while Present (Formal) loop
|
|
Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
|
|
|
|
if Present (Ctrl_Type) then
|
|
return Ctrl_Type;
|
|
end if;
|
|
|
|
Next_Formal (Formal);
|
|
end loop;
|
|
|
|
-- The subprogram may also be dispatching on result
|
|
|
|
if Present (Etype (Subp)) then
|
|
return Check_Controlling_Type (Etype (Subp), Subp);
|
|
end if;
|
|
end if;
|
|
|
|
pragma Assert (not Is_Dispatching_Operation (Subp));
|
|
return Empty;
|
|
end Find_Dispatching_Type;
|
|
|
|
---------------------------------------
|
|
-- Find_Primitive_Covering_Interface --
|
|
---------------------------------------
|
|
|
|
function Find_Primitive_Covering_Interface
|
|
(Tagged_Type : Entity_Id;
|
|
Iface_Prim : Entity_Id) return Entity_Id
|
|
is
|
|
E : Entity_Id;
|
|
|
|
begin
|
|
pragma Assert (Is_Interface (Find_Dispatching_Type (Iface_Prim))
|
|
or else (Present (Alias (Iface_Prim))
|
|
and then
|
|
Is_Interface
|
|
(Find_Dispatching_Type (Ultimate_Alias (Iface_Prim)))));
|
|
|
|
E := Current_Entity (Iface_Prim);
|
|
while Present (E) loop
|
|
if Is_Subprogram (E)
|
|
and then Is_Dispatching_Operation (E)
|
|
and then Is_Interface_Conformant (Tagged_Type, Iface_Prim, E)
|
|
then
|
|
return E;
|
|
end if;
|
|
|
|
E := Homonym (E);
|
|
end loop;
|
|
|
|
return Empty;
|
|
end Find_Primitive_Covering_Interface;
|
|
|
|
---------------------------
|
|
-- Is_Dynamically_Tagged --
|
|
---------------------------
|
|
|
|
function Is_Dynamically_Tagged (N : Node_Id) return Boolean is
|
|
begin
|
|
if Nkind (N) = N_Error then
|
|
return False;
|
|
else
|
|
return Find_Controlling_Arg (N) /= Empty;
|
|
end if;
|
|
end Is_Dynamically_Tagged;
|
|
|
|
--------------------------
|
|
-- Is_Tag_Indeterminate --
|
|
--------------------------
|
|
|
|
function Is_Tag_Indeterminate (N : Node_Id) return Boolean is
|
|
Nam : Entity_Id;
|
|
Actual : Node_Id;
|
|
Orig_Node : constant Node_Id := Original_Node (N);
|
|
|
|
begin
|
|
if Nkind (Orig_Node) = N_Function_Call
|
|
and then Is_Entity_Name (Name (Orig_Node))
|
|
then
|
|
Nam := Entity (Name (Orig_Node));
|
|
|
|
if not Has_Controlling_Result (Nam) then
|
|
return False;
|
|
|
|
-- An explicit dereference means that the call has already been
|
|
-- expanded and there is no tag to propagate.
|
|
|
|
elsif Nkind (N) = N_Explicit_Dereference then
|
|
return False;
|
|
|
|
-- If there are no actuals, the call is tag-indeterminate
|
|
|
|
elsif No (Parameter_Associations (Orig_Node)) then
|
|
return True;
|
|
|
|
else
|
|
Actual := First_Actual (Orig_Node);
|
|
while Present (Actual) loop
|
|
if Is_Controlling_Actual (Actual)
|
|
and then not Is_Tag_Indeterminate (Actual)
|
|
then
|
|
return False; -- one operand is dispatching
|
|
end if;
|
|
|
|
Next_Actual (Actual);
|
|
end loop;
|
|
|
|
return True;
|
|
end if;
|
|
|
|
elsif Nkind (Orig_Node) = N_Qualified_Expression then
|
|
return Is_Tag_Indeterminate (Expression (Orig_Node));
|
|
|
|
-- Case of a call to the Input attribute (possibly rewritten), which is
|
|
-- always tag-indeterminate except when its prefix is a Class attribute.
|
|
|
|
elsif Nkind (Orig_Node) = N_Attribute_Reference
|
|
and then
|
|
Get_Attribute_Id (Attribute_Name (Orig_Node)) = Attribute_Input
|
|
and then
|
|
Nkind (Prefix (Orig_Node)) /= N_Attribute_Reference
|
|
then
|
|
return True;
|
|
|
|
-- In Ada 2005 a function that returns an anonymous access type can
|
|
-- dispatching, and the dereference of a call to such a function
|
|
-- is also tag-indeterminate.
|
|
|
|
elsif Nkind (Orig_Node) = N_Explicit_Dereference
|
|
and then Ada_Version >= Ada_05
|
|
then
|
|
return Is_Tag_Indeterminate (Prefix (Orig_Node));
|
|
|
|
else
|
|
return False;
|
|
end if;
|
|
end Is_Tag_Indeterminate;
|
|
|
|
------------------------------------
|
|
-- Override_Dispatching_Operation --
|
|
------------------------------------
|
|
|
|
procedure Override_Dispatching_Operation
|
|
(Tagged_Type : Entity_Id;
|
|
Prev_Op : Entity_Id;
|
|
New_Op : Entity_Id)
|
|
is
|
|
Elmt : Elmt_Id;
|
|
Prim : Node_Id;
|
|
|
|
begin
|
|
-- Diagnose failure to match No_Return in parent (Ada-2005, AI-414, but
|
|
-- we do it unconditionally in Ada 95 now, since this is our pragma!)
|
|
|
|
if No_Return (Prev_Op) and then not No_Return (New_Op) then
|
|
Error_Msg_N ("procedure & must have No_Return pragma", New_Op);
|
|
Error_Msg_N ("\since overridden procedure has No_Return", New_Op);
|
|
end if;
|
|
|
|
-- If there is no previous operation to override, the type declaration
|
|
-- was malformed, and an error must have been emitted already.
|
|
|
|
Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
|
|
while Present (Elmt)
|
|
and then Node (Elmt) /= Prev_Op
|
|
loop
|
|
Next_Elmt (Elmt);
|
|
end loop;
|
|
|
|
if No (Elmt) then
|
|
return;
|
|
end if;
|
|
|
|
Replace_Elmt (Elmt, New_Op);
|
|
|
|
if Ada_Version >= Ada_05
|
|
and then Has_Interfaces (Tagged_Type)
|
|
then
|
|
-- Ada 2005 (AI-251): Update the attribute alias of all the aliased
|
|
-- entities of the overridden primitive to reference New_Op, and also
|
|
-- propagate the proper value of Is_Abstract_Subprogram. Verify
|
|
-- that the new operation is subtype conformant with the interface
|
|
-- operations that it implements (for operations inherited from the
|
|
-- parent itself, this check is made when building the derived type).
|
|
|
|
-- Note: This code is only executed in case of late overriding
|
|
|
|
Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
|
|
while Present (Elmt) loop
|
|
Prim := Node (Elmt);
|
|
|
|
if Prim = New_Op then
|
|
null;
|
|
|
|
-- Note: The check on Is_Subprogram protects the frontend against
|
|
-- reading attributes in entities that are not yet fully decorated
|
|
|
|
elsif Is_Subprogram (Prim)
|
|
and then Present (Interface_Alias (Prim))
|
|
and then Alias (Prim) = Prev_Op
|
|
and then Present (Etype (New_Op))
|
|
then
|
|
Set_Alias (Prim, New_Op);
|
|
Check_Subtype_Conformant (New_Op, Prim);
|
|
Set_Is_Abstract_Subprogram (Prim,
|
|
Is_Abstract_Subprogram (New_Op));
|
|
|
|
-- Ensure that this entity will be expanded to fill the
|
|
-- corresponding entry in its dispatch table.
|
|
|
|
if not Is_Abstract_Subprogram (Prim) then
|
|
Set_Has_Delayed_Freeze (Prim);
|
|
end if;
|
|
end if;
|
|
|
|
Next_Elmt (Elmt);
|
|
end loop;
|
|
end if;
|
|
|
|
if (not Is_Package_Or_Generic_Package (Current_Scope))
|
|
or else not In_Private_Part (Current_Scope)
|
|
then
|
|
-- Not a private primitive
|
|
|
|
null;
|
|
|
|
else pragma Assert (Is_Inherited_Operation (Prev_Op));
|
|
|
|
-- Make the overriding operation into an alias of the implicit one.
|
|
-- In this fashion a call from outside ends up calling the new body
|
|
-- even if non-dispatching, and a call from inside calls the
|
|
-- overriding operation because it hides the implicit one. To
|
|
-- indicate that the body of Prev_Op is never called, set its
|
|
-- dispatch table entity to Empty. If the overridden operation
|
|
-- has a dispatching result, so does the overriding one.
|
|
|
|
Set_Alias (Prev_Op, New_Op);
|
|
Set_DTC_Entity (Prev_Op, Empty);
|
|
Set_Has_Controlling_Result (New_Op, Has_Controlling_Result (Prev_Op));
|
|
return;
|
|
end if;
|
|
end Override_Dispatching_Operation;
|
|
|
|
-------------------
|
|
-- Propagate_Tag --
|
|
-------------------
|
|
|
|
procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id) is
|
|
Call_Node : Node_Id;
|
|
Arg : Node_Id;
|
|
|
|
begin
|
|
if Nkind (Actual) = N_Function_Call then
|
|
Call_Node := Actual;
|
|
|
|
elsif Nkind (Actual) = N_Identifier
|
|
and then Nkind (Original_Node (Actual)) = N_Function_Call
|
|
then
|
|
-- Call rewritten as object declaration when stack-checking is
|
|
-- enabled. Propagate tag to expression in declaration, which is
|
|
-- original call.
|
|
|
|
Call_Node := Expression (Parent (Entity (Actual)));
|
|
|
|
-- Ada 2005: If this is a dereference of a call to a function with a
|
|
-- dispatching access-result, the tag is propagated when the dereference
|
|
-- itself is expanded (see exp_ch6.adb) and there is nothing else to do.
|
|
|
|
elsif Nkind (Actual) = N_Explicit_Dereference
|
|
and then Nkind (Original_Node (Prefix (Actual))) = N_Function_Call
|
|
then
|
|
return;
|
|
|
|
-- Only other possibilities are parenthesized or qualified expression,
|
|
-- or an expander-generated unchecked conversion of a function call to
|
|
-- a stream Input attribute.
|
|
|
|
else
|
|
Call_Node := Expression (Actual);
|
|
end if;
|
|
|
|
-- Do not set the Controlling_Argument if already set. This happens in
|
|
-- the special case of _Input (see Exp_Attr, case Input).
|
|
|
|
if No (Controlling_Argument (Call_Node)) then
|
|
Set_Controlling_Argument (Call_Node, Control);
|
|
end if;
|
|
|
|
Arg := First_Actual (Call_Node);
|
|
|
|
while Present (Arg) loop
|
|
if Is_Tag_Indeterminate (Arg) then
|
|
Propagate_Tag (Control, Arg);
|
|
end if;
|
|
|
|
Next_Actual (Arg);
|
|
end loop;
|
|
|
|
-- Expansion of dispatching calls is suppressed when VM_Target, because
|
|
-- the VM back-ends directly handle the generation of dispatching calls
|
|
-- and would have to undo any expansion to an indirect call.
|
|
|
|
if Tagged_Type_Expansion then
|
|
Expand_Dispatching_Call (Call_Node);
|
|
|
|
-- Expansion of a dispatching call results in an indirect call, which in
|
|
-- turn causes current values to be killed (see Resolve_Call), so on VM
|
|
-- targets we do the call here to ensure consistent warnings between VM
|
|
-- and non-VM targets.
|
|
|
|
else
|
|
Kill_Current_Values;
|
|
end if;
|
|
end Propagate_Tag;
|
|
|
|
end Sem_Disp;
|