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Diffstat (limited to 'gcc-4.4.3/gcc/ada/sem_disp.adb')
| -rw-r--r-- | gcc-4.4.3/gcc/ada/sem_disp.adb | 1692 |
1 files changed, 1692 insertions, 0 deletions
diff --git a/gcc-4.4.3/gcc/ada/sem_disp.adb b/gcc-4.4.3/gcc/ada/sem_disp.adb new file mode 100644 index 000000000..a8eb3df52 --- /dev/null +++ b/gcc-4.4.3/gcc/ada/sem_disp.adb @@ -0,0 +1,1692 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S E M _ D I S P -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2008, 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_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_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 Stand; use Stand; +with Sinfo; use Sinfo; +with Targparm; use Targparm; +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 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 the controlling type is concurrent and declared within a + -- generic or inside an instance, use its 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 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 Present (Etype (Subp)) 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_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_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 (Par) = N_Function_Call or else + Nkind (Par) = N_Procedure_Call_Statement or else + Nkind (Par) = N_Assignment_Statement or else + Nkind (Par) = N_Op_Eq or else + Nkind (Par) = 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 + Actual := First_Actual (N); + + Subp_Entity := Entity (Name (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-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); + + -- 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; + + function Is_Visibly_Controlled (T : Entity_Id) return Boolean; + -- Check whether T is derived from a visibly controlled type. + -- This is true if the root type is declared in Ada.Finalization. + -- If T is derived instead from a private type whose full view + -- is controlled, an explicit Initialize/Adjust/Finalize subprogram + -- does not override the inherited one. + + --------------------------- + -- Is_Visibly_Controlled -- + --------------------------- + + function Is_Visibly_Controlled (T : Entity_Id) return Boolean is + Root : constant Entity_Id := Root_Type (T); + begin + return Chars (Scope (Root)) = Name_Finalization + and then Chars (Scope (Scope (Root))) = Name_Ada + and then Scope (Scope (Scope (Root))) = Standard_Standard; + end Is_Visibly_Controlled; + + -- Start of processing for Check_Dispatching_Operation + + 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 + -- the Init procedure) are not primitives + + elsif Is_Frozen (Tagged_Type) + and then not Comes_From_Source (Subp) + and then not Has_Dispatching_Parent + then + 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 := Next (Parent (Tagged_Type)); + + 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. + + 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 + Register_Primitive (Sloc (Subp_Body), + Prim => Subp, + Ins_Nod => Subp_Body); + end if; + + Generate_Reference (Tagged_Type, Subp, 'p', False); + 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. + + 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); + Error_Msg_NE + ("operation does not override inherited&?", Subp, Subp); + 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. + + 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 + then + Register_Primitive (Sloc (Prim), + Prim => Prim, + Ins_Nod => Subp_Body); + 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 + Formal : Entity_Id; + Ctrl_Type : Entity_Id; + + begin + if Present (DTC_Entity (Subp)) then + return Scope (DTC_Entity (Subp)); + + 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 + Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp); + + if Present (Ctrl_Type) then + return Ctrl_Type; + end if; + end if; + end if; + + 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. + + Set_Alias (Prev_Op, New_Op); + Set_DTC_Entity (Prev_Op, Empty); + 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 VM_Target = No_VM 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; |