| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- S E M _ D I S P -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1992-2003 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, 59 Temple Place - Suite 330, Boston, -- |
| -- MA 02111-1307, 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 Errout; use Errout; |
| with Hostparm; use Hostparm; |
| with Nlists; use Nlists; |
| with Opt; use Opt; |
| with Output; use Output; |
| with Sem; use Sem; |
| with Sem_Ch6; use Sem_Ch6; |
| with Sem_Eval; use Sem_Eval; |
| with Sem_Util; use Sem_Util; |
| with Snames; use Snames; |
| with Sinfo; use Sinfo; |
| with Uintp; use Uintp; |
| |
| package body Sem_Disp is |
| |
| ----------------------- |
| -- Local Subprograms -- |
| ----------------------- |
| |
| procedure Override_Dispatching_Operation |
| (Tagged_Type : Entity_Id; |
| Prev_Op : Entity_Id; |
| New_Op : Entity_Id); |
| -- Replace an implicit dispatching operation with an explicit one. |
| -- Prev_Op is an inherited primitive operation which is overridden |
| -- by the explicit declaration of New_Op. |
| |
| 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 type of a formal parameter of subp. Returns the tagged |
| -- if the parameter can be a controlling argument, empty otherwise |
| |
| -------------------------------- |
| -- 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); |
| |
| -- 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 a remote subprogram 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)) |
| and then 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; |
| 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 for internal operations. |
| |
| 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)) |
| 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; |
| Control : Node_Id := Empty; |
| Func : 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 |
| Func : constant Entity_Id := Entity (Name (N)); |
| Par : Node_Id; |
| |
| begin |
| if Is_Abstract (Func) |
| and then No (Controlling_Argument (N)) |
| then |
| if Present (Alias (Func)) |
| and then not Is_Abstract (Alias (Func)) |
| and then No (DTC_Entity (Func)) |
| then |
| -- Private overriding of inherited abstract operation, |
| -- call is legal. |
| |
| Set_Entity (Name (N), Alias (Func)); |
| 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 (Func)) |
| then |
| return; |
| |
| elsif Nkind (Par) = N_Qualified_Expression |
| or else Nkind (Par) = N_Unchecked_Type_Conversion |
| then |
| Par := Parent (Par); |
| |
| else |
| Error_Msg_N |
| ("call to abstract function must be dispatching", N); |
| 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); |
| |
| while Present (Actual) loop |
| Control := Find_Controlling_Arg (Actual); |
| exit when Present (Control); |
| Next_Actual (Actual); |
| end loop; |
| |
| 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, check that there isn't any |
| -- tag indeterminate abstract call 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))); |
| |
| -- 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 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; |
| |
| 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); |
| |
| -- 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 (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 Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body |
| and then Comes_From_Source (Subp) |
| 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 not Present (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)); |
| Insert_After ( |
| Subp_Body, Fill_DT_Entry (Sloc (Subp_Body), Subp)); |
| 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); |
| Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp); |
| Set_Is_Overriding_Operation (Subp); |
| else |
| 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); |
| |
| if Exception_Mechanism = Front_End_ZCX_Exceptions then |
| Set_Has_Subprogram_Descriptor (Old_Spec, False); |
| Set_Handler_Records (Old_Spec, No_List); |
| Set_Is_Eliminated (Old_Spec); |
| end if; |
| 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)); |
| |
| 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)); |
| |
| begin |
| -- 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; |
| |
| Replace_Elmt (Op_Elmt, New_Op); |
| |
| if (not Is_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 possibility is parenthesized or qualified expression |
| |
| 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_Dispatch_Call (Call_Node); |
| end if; |
| end Propagate_Tag; |
| |
| end Sem_Disp; |
