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Diffstat (limited to 'gcc-4.2.1/gcc/ada/sem_disp.adb')
| -rw-r--r-- | gcc-4.2.1/gcc/ada/sem_disp.adb | 1387 |
1 files changed, 1387 insertions, 0 deletions
diff --git a/gcc-4.2.1/gcc/ada/sem_disp.adb b/gcc-4.2.1/gcc/ada/sem_disp.adb new file mode 100644 index 000000000..73737dedd --- /dev/null +++ b/gcc-4.2.1/gcc/ada/sem_disp.adb @@ -0,0 +1,1387 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S E M _ D I S P -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2006, 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 2, 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 COPYING. If not, write -- +-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- +-- Boston, MA 02110-1301, USA. -- +-- -- +-- 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 Exp_Util; use Exp_Util; +with Errout; use Errout; +with Hostparm; use Hostparm; +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 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 + Append_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; + Remote : constant Boolean := + Is_Remote_Types (Current_Scope) + and then Comes_From_Source (Subp) + and then Scope (Typ) = Current_Scope; + + begin + Formal := First_Formal (Subp); + + while Present (Formal) loop + Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp); + + if Present (Ctrl_Type) then + 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 + if Ekind (Etype (Formal)) = E_Anonymous_Access_Type 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; + + -- Verify that the restriction in E.2.2 (14) is obeyed + + elsif Remote + and then Ekind (Etype (Formal)) = E_Anonymous_Access_Type + then + Error_Msg_N + ("access parameter of remote object primitive" + & " must be controlling", + Formal); + 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 the result subtype statically matches + -- the first subtype. + + if not Subtypes_Statically_Match (Typ, Etype (Subp)) then + 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; + + -- The following check is clearly required, although the RM says + -- nothing about return types. If the return type is a limited + -- class-wide type declared in the current scope, there is no way + -- to declare stream procedures for it, so the return cannot be + -- marshalled. + + elsif Remote + and then Is_Limited_Type (Typ) + and then Etype (Subp) = Class_Wide_Type (Typ) + then + Error_Msg_N ("return type has no stream attributes", Subp); + 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 (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 (Subp)) + or else + (Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration + and then + Present (Corresponding_Formal_Spec (Parent (Parent (Subp)))) + and then + Is_Abstract (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 + Actual : Node_Id; + Formal : Entity_Id; + Control : Node_Id := Empty; + Func : Entity_Id; + Subp_Entity : Entity_Id; + Loc : constant Source_Ptr := Sloc (N); + Indeterm_Ancestor_Call : Boolean := False; + Indeterm_Ctrl_Type : Entity_Id; + + 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 (Subp) + and then No (Controlling_Argument (N)) + then + if Present (Alias (Subp)) + and then not Is_Abstract (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); + 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 + 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); + + 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 + -- consituent expression is itself a call. + + else + Func := + Entity (Name + (Original_Node + (Expression (Original_Node (Actual))))); + end if; + + if Present (Func) and then Is_Abstract (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; + + -- 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 + 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. + + 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 + Insert_After (Subp_Body, + Fill_DT_Entry (Sloc (Subp_Body), 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 overridding + -- 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 ot 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 + 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); + 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); + + 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 one 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 + Prepend_Elmt (Subp, New_Prim); + 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); + + if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then + Append_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 (Old_Subp, Is_Abstract (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 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; + + --------------------------- + -- Is_Dynamically_Tagged -- + --------------------------- + + function Is_Dynamically_Tagged (N : Node_Id) return Boolean is + begin + return Find_Controlling_Arg (N) /= Empty; + 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; + 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 + Op_Elmt : Elmt_Id := First_Elmt (Primitive_Operations (Tagged_Type)); + Elmt : Elmt_Id; + Found : Boolean; + E : Entity_Id; + + function Is_Interface_Subprogram (Op : Entity_Id) return Boolean; + -- Traverse the list of aliased entities to check if the overriden + -- entity corresponds with a primitive operation of an abstract + -- interface type. + + ----------------------------- + -- Is_Interface_Subprogram -- + ----------------------------- + + function Is_Interface_Subprogram (Op : Entity_Id) return Boolean is + Aux : Entity_Id; + + begin + Aux := Op; + while Present (Alias (Aux)) + and then Present (DTC_Entity (Alias (Aux))) + loop + if Is_Interface (Scope (DTC_Entity (Alias (Aux)))) then + return True; + end if; + Aux := Alias (Aux); + end loop; + + return False; + end Is_Interface_Subprogram; + + -- Start of processing for Override_Dispatching_Operation + + 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; + + -- Patch the primitive operation list + + while Present (Op_Elmt) + and then Node (Op_Elmt) /= Prev_Op + loop + Next_Elmt (Op_Elmt); + end loop; + + -- If there is no previous operation to override, the type declaration + -- was malformed, and an error must have been emitted already. + + if No (Op_Elmt) then + return; + end if; + + -- Ada 2005 (AI-251): Do not replace subprograms inherited from + -- abstract interfaces. They will be used later to generate the + -- corresponding thunks to initialize the Vtable (see subprogram + -- Freeze_Subprogram). The inherited operation itself must also + -- become hidden, to avoid spurious ambiguities; name resolution + -- must pick up only the operation that implements it, + + if Is_Interface_Subprogram (Prev_Op) then + Set_DT_Position (Prev_Op, DT_Position (Alias (Prev_Op))); + Set_Is_Abstract (Prev_Op, Is_Abstract (New_Op)); + Set_Is_Overriding_Operation (Prev_Op); + + -- Traverse the list of aliased entities to look for the overriden + -- abstract interface subprogram. + + E := Alias (Prev_Op); + while Present (Alias (E)) + and then Present (DTC_Entity (E)) + and then not (Is_Abstract (E)) + and then not Is_Interface (Scope (DTC_Entity (E))) + loop + E := Alias (E); + end loop; + + Set_Abstract_Interface_Alias (Prev_Op, E); + Set_Alias (Prev_Op, New_Op); + Set_Is_Internal (Prev_Op); + Set_Is_Hidden (Prev_Op); + + -- Override predefined primitive operations + + if Is_Predefined_Dispatching_Operation (Prev_Op) then + Replace_Elmt (Op_Elmt, New_Op); + return; + end if; + + -- Check if this primitive operation was previously added for another + -- interface. + + Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); + Found := False; + while Present (Elmt) loop + if Node (Elmt) = New_Op then + Found := True; + exit; + end if; + + Next_Elmt (Elmt); + end loop; + + if not Found then + Append_Elmt (New_Op, Primitive_Operations (Tagged_Type)); + end if; + + return; + + else + Replace_Elmt (Op_Elmt, New_Op); + 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))); + + -- 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 Java_VM, because + -- the JVM back end directly handles the generation of dispatching + -- calls and would have to undo any expansion to an indirect call. + + if not Java_VM then + Expand_Dispatching_Call (Call_Node); + end if; + end Propagate_Tag; + +end Sem_Disp; |