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rt_gccstream/gcc/ada/sem_disp.adb

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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ D I S P --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Atree; use Atree;
with Debug; use Debug;
with Elists; use Elists;
with Einfo; use Einfo;
with Exp_Disp; use Exp_Disp;
with Exp_Util; use Exp_Util;
with Exp_Ch7; use Exp_Ch7;
with Exp_Tss; use Exp_Tss;
with Errout; use Errout;
with Lib.Xref; use Lib.Xref;
with Namet; use Namet;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Output; use Output;
with Restrict; use Restrict;
with Rident; use Rident;
with Sem; use Sem;
with Sem_Aux; use Sem_Aux;
with Sem_Ch3; use Sem_Ch3;
with Sem_Ch6; use Sem_Ch6;
with Sem_Eval; use Sem_Eval;
with Sem_Type; use Sem_Type;
with Sem_Util; use Sem_Util;
with Snames; use Snames;
with Sinfo; use Sinfo;
with Tbuild; use Tbuild;
with Uintp; use Uintp;
package body Sem_Disp is
-----------------------
-- Local Subprograms --
-----------------------
procedure Add_Dispatching_Operation
(Tagged_Type : Entity_Id;
New_Op : Entity_Id);
-- Add New_Op in the list of primitive operations of Tagged_Type
function Check_Controlling_Type
(T : Entity_Id;
Subp : Entity_Id) return Entity_Id;
-- T is the tagged type of a formal parameter or the result of Subp.
-- If the subprogram has a controlling parameter or result that matches
-- the type, then returns the tagged type of that parameter or result
-- (returning the designated tagged type in the case of an access
-- parameter); otherwise returns empty.
-------------------------------
-- Add_Dispatching_Operation --
-------------------------------
procedure Add_Dispatching_Operation
(Tagged_Type : Entity_Id;
New_Op : Entity_Id)
is
List : constant Elist_Id := Primitive_Operations (Tagged_Type);
begin
-- The dispatching operation may already be on the list, if it is the
-- wrapper for an inherited function of a null extension (see Exp_Ch3
-- for the construction of function wrappers). The list of primitive
-- operations must not contain duplicates.
Append_Unique_Elmt (New_Op, List);
end Add_Dispatching_Operation;
-------------------------------
-- Check_Controlling_Formals --
-------------------------------
procedure Check_Controlling_Formals
(Typ : Entity_Id;
Subp : Entity_Id)
is
Formal : Entity_Id;
Ctrl_Type : Entity_Id;
begin
Formal := First_Formal (Subp);
while Present (Formal) loop
Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
if Present (Ctrl_Type) then
-- When controlling type is concurrent and declared within a
-- generic or inside an instance use corresponding record type.
if Is_Concurrent_Type (Ctrl_Type)
and then Present (Corresponding_Record_Type (Ctrl_Type))
then
Ctrl_Type := Corresponding_Record_Type (Ctrl_Type);
end if;
if Ctrl_Type = Typ then
Set_Is_Controlling_Formal (Formal);
-- Ada 2005 (AI-231): Anonymous access types that are used in
-- controlling parameters exclude null because it is necessary
-- to read the tag to dispatch, and null has no tag.
if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
Set_Can_Never_Be_Null (Etype (Formal));
Set_Is_Known_Non_Null (Etype (Formal));
end if;
-- Check that the parameter's nominal subtype statically
-- matches the first subtype.
if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
if not Subtypes_Statically_Match
(Typ, Designated_Type (Etype (Formal)))
then
Error_Msg_N
("parameter subtype does not match controlling type",
Formal);
end if;
elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) then
Error_Msg_N
("parameter subtype does not match controlling type",
Formal);
end if;
if Present (Default_Value (Formal)) then
-- In Ada 2005, access parameters can have defaults
if Ekind (Etype (Formal)) = E_Anonymous_Access_Type
and then Ada_Version < Ada_05
then
Error_Msg_N
("default not allowed for controlling access parameter",
Default_Value (Formal));
elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then
Error_Msg_N
("default expression must be a tag indeterminate" &
" function call", Default_Value (Formal));
end if;
end if;
elsif Comes_From_Source (Subp) then
Error_Msg_N
("operation can be dispatching in only one type", Subp);
end if;
end if;
Next_Formal (Formal);
end loop;
if Ekind (Subp) = E_Function
or else
Ekind (Subp) = E_Generic_Function
then
Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp);
if Present (Ctrl_Type) then
if Ctrl_Type = Typ then
Set_Has_Controlling_Result (Subp);
-- Check that result subtype statically matches first subtype
-- (Ada 2005): Subp may have a controlling access result.
if Subtypes_Statically_Match (Typ, Etype (Subp))
or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type
and then
Subtypes_Statically_Match
(Typ, Designated_Type (Etype (Subp))))
then
null;
else
Error_Msg_N
("result subtype does not match controlling type", Subp);
end if;
elsif Comes_From_Source (Subp) then
Error_Msg_N
("operation can be dispatching in only one type", Subp);
end if;
end if;
end if;
end Check_Controlling_Formals;
----------------------------
-- Check_Controlling_Type --
----------------------------
function Check_Controlling_Type
(T : Entity_Id;
Subp : Entity_Id) return Entity_Id
is
Tagged_Type : Entity_Id := Empty;
begin
if Is_Tagged_Type (T) then
if Is_First_Subtype (T) then
Tagged_Type := T;
else
Tagged_Type := Base_Type (T);
end if;
elsif Ekind (T) = E_Anonymous_Access_Type
and then Is_Tagged_Type (Designated_Type (T))
then
if Ekind (Designated_Type (T)) /= E_Incomplete_Type then
if Is_First_Subtype (Designated_Type (T)) then
Tagged_Type := Designated_Type (T);
else
Tagged_Type := Base_Type (Designated_Type (T));
end if;
-- Ada 2005: an incomplete type can be tagged. An operation with an
-- access parameter of the type is dispatching.
elsif Scope (Designated_Type (T)) = Current_Scope then
Tagged_Type := Designated_Type (T);
-- Ada 2005 (AI-50217)
elsif From_With_Type (Designated_Type (T))
and then Present (Non_Limited_View (Designated_Type (T)))
then
if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then
Tagged_Type := Non_Limited_View (Designated_Type (T));
else
Tagged_Type := Base_Type (Non_Limited_View
(Designated_Type (T)));
end if;
end if;
end if;
if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then
return Empty;
-- The dispatching type and the primitive operation must be defined in
-- the same scope, except in the case of internal operations and formal
-- abstract subprograms.
elsif ((Scope (Subp) = Scope (Tagged_Type) or else Is_Internal (Subp))
and then (not Is_Generic_Type (Tagged_Type)
or else not Comes_From_Source (Subp)))
or else
(Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp))
or else
(Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration
and then
Present (Corresponding_Formal_Spec (Parent (Parent (Subp))))
and then
Is_Abstract_Subprogram (Subp))
then
return Tagged_Type;
else
return Empty;
end if;
end Check_Controlling_Type;
----------------------------
-- Check_Dispatching_Call --
----------------------------
procedure Check_Dispatching_Call (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Actual : Node_Id;
Formal : Entity_Id;
Control : Node_Id := Empty;
Func : Entity_Id;
Subp_Entity : Entity_Id;
Indeterm_Ancestor_Call : Boolean := False;
Indeterm_Ctrl_Type : Entity_Id;
Static_Tag : Node_Id := Empty;
-- If a controlling formal has a statically tagged actual, the tag of
-- this actual is to be used for any tag-indeterminate actual.
procedure Check_Direct_Call;
-- In the case when the controlling actual is a class-wide type whose
-- root type's completion is a task or protected type, the call is in
-- fact direct. This routine detects the above case and modifies the
-- call accordingly.
procedure Check_Dispatching_Context;
-- If the call is tag-indeterminate and the entity being called is
-- abstract, verify that the context is a call that will eventually
-- provide a tag for dispatching, or has provided one already.
-----------------------
-- Check_Direct_Call --
-----------------------
procedure Check_Direct_Call is
Typ : Entity_Id := Etype (Control);
function Is_User_Defined_Equality (Id : Entity_Id) return Boolean;
-- Determine whether an entity denotes a user-defined equality
------------------------------
-- Is_User_Defined_Equality --
------------------------------
function Is_User_Defined_Equality (Id : Entity_Id) return Boolean is
begin
return
Ekind (Id) = E_Function
and then Chars (Id) = Name_Op_Eq
and then Comes_From_Source (Id)
-- Internally generated equalities have a full type declaration
-- as their parent.
and then Nkind (Parent (Id)) = N_Function_Specification;
end Is_User_Defined_Equality;
-- Start of processing for Check_Direct_Call
begin
-- Predefined primitives do not receive wrappers since they are built
-- from scratch for the corresponding record of synchronized types.
-- Equality is in general predefined, but is excluded from the check
-- when it is user-defined.
if Is_Predefined_Dispatching_Operation (Subp_Entity)
and then not Is_User_Defined_Equality (Subp_Entity)
then
return;
end if;
if Is_Class_Wide_Type (Typ) then
Typ := Root_Type (Typ);
end if;
if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then
Typ := Full_View (Typ);
end if;
if Is_Concurrent_Type (Typ)
and then
Present (Corresponding_Record_Type (Typ))
then
Typ := Corresponding_Record_Type (Typ);
-- The concurrent record's list of primitives should contain a
-- wrapper for the entity of the call, retrieve it.
declare
Prim : Entity_Id;
Prim_Elmt : Elmt_Id;
Wrapper_Found : Boolean := False;
begin
Prim_Elmt := First_Elmt (Primitive_Operations (Typ));
while Present (Prim_Elmt) loop
Prim := Node (Prim_Elmt);
if Is_Primitive_Wrapper (Prim)
and then Wrapped_Entity (Prim) = Subp_Entity
then
Wrapper_Found := True;
exit;
end if;
Next_Elmt (Prim_Elmt);
end loop;
-- A primitive declared between two views should have a
-- corresponding wrapper.
pragma Assert (Wrapper_Found);
-- Modify the call by setting the proper entity
Set_Entity (Name (N), Prim);
end;
end if;
end Check_Direct_Call;
-------------------------------
-- Check_Dispatching_Context --
-------------------------------
procedure Check_Dispatching_Context is
Subp : constant Entity_Id := Entity (Name (N));
Par : Node_Id;
begin
if Is_Abstract_Subprogram (Subp)
and then No (Controlling_Argument (N))
then
if Present (Alias (Subp))
and then not Is_Abstract_Subprogram (Alias (Subp))
and then No (DTC_Entity (Subp))
then
-- Private overriding of inherited abstract operation, call is
-- legal.
Set_Entity (Name (N), Alias (Subp));
return;
else
Par := Parent (N);
while Present (Par) loop
if Nkind_In (Par, N_Function_Call,
N_Procedure_Call_Statement,
N_Assignment_Statement,
N_Op_Eq,
N_Op_Ne)
and then Is_Tagged_Type (Etype (Subp))
then
return;
elsif Nkind (Par) = N_Qualified_Expression
or else Nkind (Par) = N_Unchecked_Type_Conversion
then
Par := Parent (Par);
else
if Ekind (Subp) = E_Function then
Error_Msg_N
("call to abstract function must be dispatching", N);
-- This error can occur for a procedure in the case of a
-- call to an abstract formal procedure with a statically
-- tagged operand.
else
Error_Msg_N
("call to abstract procedure must be dispatching",
N);
end if;
return;
end if;
end loop;
end if;
end if;
end Check_Dispatching_Context;
-- Start of processing for Check_Dispatching_Call
begin
-- Find a controlling argument, if any
if Present (Parameter_Associations (N)) then
Subp_Entity := Entity (Name (N));
Actual := First_Actual (N);
Formal := First_Formal (Subp_Entity);
while Present (Actual) loop
Control := Find_Controlling_Arg (Actual);
exit when Present (Control);
-- Check for the case where the actual is a tag-indeterminate call
-- whose result type is different than the tagged type associated
-- with the containing call, but is an ancestor of the type.
if Is_Controlling_Formal (Formal)
and then Is_Tag_Indeterminate (Actual)
and then Base_Type (Etype (Actual)) /= Base_Type (Etype (Formal))
and then Is_Ancestor (Etype (Actual), Etype (Formal))
then
Indeterm_Ancestor_Call := True;
Indeterm_Ctrl_Type := Etype (Formal);
-- If the formal is controlling but the actual is not, the type
-- of the actual is statically known, and may be used as the
-- controlling tag for some other tag-indeterminate actual.
elsif Is_Controlling_Formal (Formal)
and then Is_Entity_Name (Actual)
and then Is_Tagged_Type (Etype (Actual))
then
Static_Tag := Actual;
end if;
Next_Actual (Actual);
Next_Formal (Formal);
end loop;
-- If the call doesn't have a controlling actual but does have an
-- indeterminate actual that requires dispatching treatment, then an
-- object is needed that will serve as the controlling argument for a
-- dispatching call on the indeterminate actual. This can only occur
-- in the unusual situation of a default actual given by a
-- tag-indeterminate call and where the type of the call is an
-- ancestor of the type associated with a containing call to an
-- inherited operation (see AI-239).
-- Rather than create an object of the tagged type, which would be
-- problematic for various reasons (default initialization,
-- discriminants), the tag of the containing call's associated tagged
-- type is directly used to control the dispatching.
if No (Control)
and then Indeterm_Ancestor_Call
and then No (Static_Tag)
then
Control :=
Make_Attribute_Reference (Loc,
Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc),
Attribute_Name => Name_Tag);
Analyze (Control);
end if;
if Present (Control) then
-- Verify that no controlling arguments are statically tagged
if Debug_Flag_E then
Write_Str ("Found Dispatching call");
Write_Int (Int (N));
Write_Eol;
end if;
Actual := First_Actual (N);
while Present (Actual) loop
if Actual /= Control then
if not Is_Controlling_Actual (Actual) then
null; -- Can be anything
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;
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