| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- S E M _ C H 5 -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1992-2022, 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 Aspects; use Aspects; |
| with Atree; use Atree; |
| with Checks; use Checks; |
| with Debug; use Debug; |
| with Einfo; use Einfo; |
| with Einfo.Entities; use Einfo.Entities; |
| with Einfo.Utils; use Einfo.Utils; |
| with Errout; use Errout; |
| with Expander; use Expander; |
| with Exp_Ch6; use Exp_Ch6; |
| with Exp_Tss; use Exp_Tss; |
| with Exp_Util; use Exp_Util; |
| with Freeze; use Freeze; |
| with Ghost; use Ghost; |
| with Lib; use Lib; |
| with Lib.Xref; use Lib.Xref; |
| with Namet; use Namet; |
| with Nlists; use Nlists; |
| with Nmake; use Nmake; |
| with Opt; use Opt; |
| with Sem; use Sem; |
| with Sem_Aux; use Sem_Aux; |
| with Sem_Case; use Sem_Case; |
| with Sem_Ch3; use Sem_Ch3; |
| with Sem_Ch6; use Sem_Ch6; |
| with Sem_Ch8; use Sem_Ch8; |
| with Sem_Dim; use Sem_Dim; |
| with Sem_Disp; use Sem_Disp; |
| with Sem_Elab; use Sem_Elab; |
| with Sem_Eval; use Sem_Eval; |
| with Sem_Res; use Sem_Res; |
| with Sem_Type; use Sem_Type; |
| with Sem_Util; use Sem_Util; |
| with Sem_Warn; use Sem_Warn; |
| with Snames; use Snames; |
| with Stand; use Stand; |
| with Sinfo; use Sinfo; |
| with Sinfo.Nodes; use Sinfo.Nodes; |
| with Sinfo.Utils; use Sinfo.Utils; |
| with Targparm; use Targparm; |
| with Tbuild; use Tbuild; |
| with Ttypes; use Ttypes; |
| with Uintp; use Uintp; |
| |
| package body Sem_Ch5 is |
| |
| Current_Assignment : Node_Id := Empty; |
| -- This variable holds the node for an assignment that contains target |
| -- names. The corresponding flag has been set by the parser, and when |
| -- set the analysis of the RHS must be done with all expansion disabled, |
| -- because the assignment is reanalyzed after expansion has replaced all |
| -- occurrences of the target name appropriately. |
| |
| Unblocked_Exit_Count : Nat := 0; |
| -- This variable is used when processing if statements, case statements, |
| -- and block statements. It counts the number of exit points that are not |
| -- blocked by unconditional transfer instructions: for IF and CASE, these |
| -- are the branches of the conditional; for a block, they are the statement |
| -- sequence of the block, and the statement sequences of any exception |
| -- handlers that are part of the block. When processing is complete, if |
| -- this count is zero, it means that control cannot fall through the IF, |
| -- CASE or block statement. This is used for the generation of warning |
| -- messages. This variable is recursively saved on entry to processing the |
| -- construct, and restored on exit. |
| |
| function Has_Sec_Stack_Call (N : Node_Id) return Boolean; |
| -- N is the node for an arbitrary construct. This function searches the |
| -- construct N to see if any expressions within it contain function |
| -- calls that use the secondary stack, returning True if any such call |
| -- is found, and False otherwise. |
| |
| procedure Preanalyze_Range (R_Copy : Node_Id); |
| -- Determine expected type of range or domain of iteration of Ada 2012 |
| -- loop by analyzing separate copy. Do the analysis and resolution of the |
| -- copy of the bound(s) with expansion disabled, to prevent the generation |
| -- of finalization actions. This prevents memory leaks when the bounds |
| -- contain calls to functions returning controlled arrays or when the |
| -- domain of iteration is a container. |
| |
| ------------------------ |
| -- Analyze_Assignment -- |
| ------------------------ |
| |
| -- WARNING: This routine manages Ghost regions. Return statements must be |
| -- replaced by gotos which jump to the end of the routine and restore the |
| -- Ghost mode. |
| |
| procedure Analyze_Assignment (N : Node_Id) is |
| Lhs : constant Node_Id := Name (N); |
| Rhs : Node_Id := Expression (N); |
| |
| procedure Diagnose_Non_Variable_Lhs (N : Node_Id); |
| -- N is the node for the left hand side of an assignment, and it is not |
| -- a variable. This routine issues an appropriate diagnostic. |
| |
| function Is_Protected_Part_Of_Constituent |
| (Nod : Node_Id) return Boolean; |
| -- Determine whether arbitrary node Nod denotes a Part_Of constituent of |
| -- a single protected type. |
| |
| procedure Kill_Lhs; |
| -- This is called to kill current value settings of a simple variable |
| -- on the left hand side. We call it if we find any error in analyzing |
| -- the assignment, and at the end of processing before setting any new |
| -- current values in place. |
| |
| procedure Set_Assignment_Type |
| (Opnd : Node_Id; |
| Opnd_Type : in out Entity_Id); |
| -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the |
| -- nominal subtype. This procedure is used to deal with cases where the |
| -- nominal subtype must be replaced by the actual subtype. |
| |
| procedure Transform_BIP_Assignment (Typ : Entity_Id); |
| function Should_Transform_BIP_Assignment |
| (Typ : Entity_Id) return Boolean; |
| -- If the right-hand side of an assignment statement is a build-in-place |
| -- call we cannot build in place, so we insert a temp initialized with |
| -- the call, and transform the assignment statement to copy the temp. |
| -- Transform_BIP_Assignment does the transformation, and |
| -- Should_Transform_BIP_Assignment determines whether we should. |
| -- The same goes for qualified expressions and conversions whose |
| -- operand is such a call. |
| -- |
| -- This is only for nonlimited types; assignment statements are illegal |
| -- for limited types, but are generated internally for aggregates and |
| -- init procs. These limited-type are not really assignment statements |
| -- -- conceptually, they are initializations, so should not be |
| -- transformed. |
| -- |
| -- Similarly, for nonlimited types, aggregates and init procs generate |
| -- assignment statements that are really initializations. These are |
| -- marked No_Ctrl_Actions. |
| |
| function Within_Function return Boolean; |
| -- Determine whether the current scope is a function or appears within |
| -- one. |
| |
| ------------------------------- |
| -- Diagnose_Non_Variable_Lhs -- |
| ------------------------------- |
| |
| procedure Diagnose_Non_Variable_Lhs (N : Node_Id) is |
| begin |
| -- Not worth posting another error if left hand side already flagged |
| -- as being illegal in some respect. |
| |
| if Error_Posted (N) then |
| return; |
| |
| -- Some special bad cases of entity names |
| |
| elsif Is_Entity_Name (N) then |
| declare |
| Ent : constant Entity_Id := Entity (N); |
| |
| begin |
| if Ekind (Ent) = E_Loop_Parameter |
| or else Is_Loop_Parameter (Ent) |
| then |
| Error_Msg_N ("assignment to loop parameter not allowed", N); |
| return; |
| |
| elsif Ekind (Ent) = E_In_Parameter then |
| Error_Msg_N |
| ("assignment to IN mode parameter not allowed", N); |
| return; |
| |
| -- Renamings of protected private components are turned into |
| -- constants when compiling a protected function. In the case |
| -- of single protected types, the private component appears |
| -- directly. |
| |
| elsif (Is_Prival (Ent) and then Within_Function) |
| or else Is_Protected_Component (Ent) |
| then |
| Error_Msg_N |
| ("protected function cannot modify its protected object", |
| N); |
| return; |
| end if; |
| end; |
| |
| -- For indexed components, test prefix if it is in array. We do not |
| -- want to recurse for cases where the prefix is a pointer, since we |
| -- may get a message confusing the pointer and what it references. |
| |
| elsif Nkind (N) = N_Indexed_Component |
| and then Is_Array_Type (Etype (Prefix (N))) |
| then |
| Diagnose_Non_Variable_Lhs (Prefix (N)); |
| return; |
| |
| -- Another special case for assignment to discriminant |
| |
| elsif Nkind (N) = N_Selected_Component then |
| if Present (Entity (Selector_Name (N))) |
| and then Ekind (Entity (Selector_Name (N))) = E_Discriminant |
| then |
| Error_Msg_N ("assignment to discriminant not allowed", N); |
| return; |
| |
| -- For selection from record, diagnose prefix, but note that again |
| -- we only do this for a record, not e.g. for a pointer. |
| |
| elsif Is_Record_Type (Etype (Prefix (N))) then |
| Diagnose_Non_Variable_Lhs (Prefix (N)); |
| return; |
| end if; |
| end if; |
| |
| -- If we fall through, we have no special message to issue |
| |
| Error_Msg_N ("left hand side of assignment must be a variable", N); |
| end Diagnose_Non_Variable_Lhs; |
| |
| -------------------------------------- |
| -- Is_Protected_Part_Of_Constituent -- |
| -------------------------------------- |
| |
| function Is_Protected_Part_Of_Constituent |
| (Nod : Node_Id) return Boolean |
| is |
| Encap_Id : Entity_Id; |
| Var_Id : Entity_Id; |
| |
| begin |
| -- Abstract states and variables may act as Part_Of constituents of |
| -- single protected types, however only variables can be modified by |
| -- an assignment. |
| |
| if Is_Entity_Name (Nod) then |
| Var_Id := Entity (Nod); |
| |
| if Present (Var_Id) and then Ekind (Var_Id) = E_Variable then |
| Encap_Id := Encapsulating_State (Var_Id); |
| |
| -- To qualify, the node must denote a reference to a variable |
| -- whose encapsulating state is a single protected object. |
| |
| return |
| Present (Encap_Id) |
| and then Is_Single_Protected_Object (Encap_Id); |
| end if; |
| end if; |
| |
| return False; |
| end Is_Protected_Part_Of_Constituent; |
| |
| -------------- |
| -- Kill_Lhs -- |
| -------------- |
| |
| procedure Kill_Lhs is |
| begin |
| if Is_Entity_Name (Lhs) then |
| declare |
| Ent : constant Entity_Id := Entity (Lhs); |
| begin |
| if Present (Ent) then |
| Kill_Current_Values (Ent); |
| end if; |
| end; |
| end if; |
| end Kill_Lhs; |
| |
| ------------------------- |
| -- Set_Assignment_Type -- |
| ------------------------- |
| |
| procedure Set_Assignment_Type |
| (Opnd : Node_Id; |
| Opnd_Type : in out Entity_Id) |
| is |
| Decl : Node_Id; |
| |
| begin |
| Require_Entity (Opnd); |
| |
| -- If the assignment operand is an in-out or out parameter, then we |
| -- get the actual subtype (needed for the unconstrained case). If the |
| -- operand is the actual in an entry declaration, then within the |
| -- accept statement it is replaced with a local renaming, which may |
| -- also have an actual subtype. |
| |
| if Is_Entity_Name (Opnd) |
| and then (Ekind (Entity (Opnd)) in E_Out_Parameter |
| | E_In_Out_Parameter |
| | E_Generic_In_Out_Parameter |
| or else |
| (Ekind (Entity (Opnd)) = E_Variable |
| and then Nkind (Parent (Entity (Opnd))) = |
| N_Object_Renaming_Declaration |
| and then Nkind (Parent (Parent (Entity (Opnd)))) = |
| N_Accept_Statement)) |
| then |
| Opnd_Type := Get_Actual_Subtype (Opnd); |
| |
| -- If assignment operand is a component reference, then we get the |
| -- actual subtype of the component for the unconstrained case. |
| |
| elsif Nkind (Opnd) in N_Selected_Component | N_Explicit_Dereference |
| and then not Is_Unchecked_Union (Opnd_Type) |
| then |
| Decl := Build_Actual_Subtype_Of_Component (Opnd_Type, Opnd); |
| |
| if Present (Decl) then |
| Insert_Action (N, Decl); |
| Mark_Rewrite_Insertion (Decl); |
| Analyze (Decl); |
| Opnd_Type := Defining_Identifier (Decl); |
| Set_Etype (Opnd, Opnd_Type); |
| Freeze_Itype (Opnd_Type, N); |
| |
| elsif Is_Constrained (Etype (Opnd)) then |
| Opnd_Type := Etype (Opnd); |
| end if; |
| |
| -- For slice, use the constrained subtype created for the slice |
| |
| elsif Nkind (Opnd) = N_Slice then |
| Opnd_Type := Etype (Opnd); |
| end if; |
| end Set_Assignment_Type; |
| |
| ------------------------------------- |
| -- Should_Transform_BIP_Assignment -- |
| ------------------------------------- |
| |
| function Should_Transform_BIP_Assignment |
| (Typ : Entity_Id) return Boolean |
| is |
| begin |
| if Expander_Active |
| and then not Is_Limited_View (Typ) |
| and then Is_Build_In_Place_Result_Type (Typ) |
| and then not No_Ctrl_Actions (N) |
| then |
| -- This function is called early, before name resolution is |
| -- complete, so we have to deal with things that might turn into |
| -- function calls later. N_Function_Call and N_Op nodes are the |
| -- obvious case. An N_Identifier or N_Expanded_Name is a |
| -- parameterless function call if it denotes a function. |
| -- Finally, an attribute reference can be a function call. |
| |
| declare |
| Unqual_Rhs : constant Node_Id := Unqual_Conv (Rhs); |
| begin |
| case Nkind (Unqual_Rhs) is |
| when N_Function_Call |
| | N_Op |
| => |
| return True; |
| |
| when N_Expanded_Name |
| | N_Identifier |
| => |
| return |
| Ekind (Entity (Unqual_Rhs)) in E_Function | E_Operator; |
| |
| -- T'Input will turn into a call whose result type is T |
| |
| when N_Attribute_Reference => |
| return Attribute_Name (Unqual_Rhs) = Name_Input; |
| |
| when others => |
| return False; |
| end case; |
| end; |
| else |
| return False; |
| end if; |
| end Should_Transform_BIP_Assignment; |
| |
| ------------------------------ |
| -- Transform_BIP_Assignment -- |
| ------------------------------ |
| |
| procedure Transform_BIP_Assignment (Typ : Entity_Id) is |
| |
| -- Tranform "X : [constant] T := F (...);" into: |
| -- |
| -- Temp : constant T := F (...); |
| -- X := Temp; |
| |
| Loc : constant Source_Ptr := Sloc (N); |
| Def_Id : constant Entity_Id := Make_Temporary (Loc, 'Y', Rhs); |
| Obj_Decl : constant Node_Id := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Def_Id, |
| Constant_Present => True, |
| Object_Definition => New_Occurrence_Of (Typ, Loc), |
| Expression => Rhs, |
| Has_Init_Expression => True); |
| |
| begin |
| Set_Etype (Def_Id, Typ); |
| Set_Expression (N, New_Occurrence_Of (Def_Id, Loc)); |
| |
| -- At this point, Rhs is no longer equal to Expression (N), so: |
| |
| Rhs := Expression (N); |
| |
| Insert_Action (N, Obj_Decl); |
| end Transform_BIP_Assignment; |
| |
| --------------------- |
| -- Within_Function -- |
| --------------------- |
| |
| function Within_Function return Boolean is |
| Scop_Id : constant Entity_Id := Current_Scope; |
| |
| begin |
| if Ekind (Scop_Id) = E_Function then |
| return True; |
| |
| elsif Ekind (Enclosing_Dynamic_Scope (Scop_Id)) = E_Function then |
| return True; |
| end if; |
| |
| return False; |
| end Within_Function; |
| |
| -- Local variables |
| |
| Saved_GM : constant Ghost_Mode_Type := Ghost_Mode; |
| Saved_IGR : constant Node_Id := Ignored_Ghost_Region; |
| -- Save the Ghost-related attributes to restore on exit |
| |
| T1 : Entity_Id; |
| T2 : Entity_Id; |
| |
| Save_Full_Analysis : Boolean := False; |
| -- Force initialization to facilitate static analysis |
| |
| -- Start of processing for Analyze_Assignment |
| |
| begin |
| Mark_Coextensions (N, Rhs); |
| |
| -- Preserve relevant elaboration-related attributes of the context which |
| -- are no longer available or very expensive to recompute once analysis, |
| -- resolution, and expansion are over. |
| |
| Mark_Elaboration_Attributes |
| (N_Id => N, |
| Checks => True, |
| Modes => True); |
| |
| -- An assignment statement is Ghost when the left hand side denotes a |
| -- Ghost entity. Set the mode now to ensure that any nodes generated |
| -- during analysis and expansion are properly marked as Ghost. |
| |
| Mark_And_Set_Ghost_Assignment (N); |
| |
| if Has_Target_Names (N) then |
| pragma Assert (No (Current_Assignment)); |
| Current_Assignment := N; |
| Expander_Mode_Save_And_Set (False); |
| Save_Full_Analysis := Full_Analysis; |
| Full_Analysis := False; |
| end if; |
| |
| Analyze (Lhs); |
| Analyze (Rhs); |
| |
| -- Ensure that we never do an assignment on a variable marked as |
| -- Is_Safe_To_Reevaluate. |
| |
| pragma Assert |
| (not Is_Entity_Name (Lhs) |
| or else Ekind (Entity (Lhs)) /= E_Variable |
| or else not Is_Safe_To_Reevaluate (Entity (Lhs))); |
| |
| -- Start type analysis for assignment |
| |
| T1 := Etype (Lhs); |
| |
| -- In the most general case, both Lhs and Rhs can be overloaded, and we |
| -- must compute the intersection of the possible types on each side. |
| |
| if Is_Overloaded (Lhs) then |
| declare |
| I : Interp_Index; |
| It : Interp; |
| |
| begin |
| T1 := Any_Type; |
| Get_First_Interp (Lhs, I, It); |
| |
| while Present (It.Typ) loop |
| |
| -- An indexed component with generalized indexing is always |
| -- overloaded with the corresponding dereference. Discard the |
| -- interpretation that yields a reference type, which is not |
| -- assignable. |
| |
| if Nkind (Lhs) = N_Indexed_Component |
| and then Present (Generalized_Indexing (Lhs)) |
| and then Has_Implicit_Dereference (It.Typ) |
| then |
| null; |
| |
| -- This may be a call to a parameterless function through an |
| -- implicit dereference, so discard interpretation as well. |
| |
| elsif Is_Entity_Name (Lhs) |
| and then Has_Implicit_Dereference (It.Typ) |
| then |
| null; |
| |
| elsif Has_Compatible_Type (Rhs, It.Typ) then |
| if T1 = Any_Type then |
| T1 := It.Typ; |
| else |
| -- An explicit dereference is overloaded if the prefix |
| -- is. Try to remove the ambiguity on the prefix, the |
| -- error will be posted there if the ambiguity is real. |
| |
| if Nkind (Lhs) = N_Explicit_Dereference then |
| declare |
| PI : Interp_Index; |
| PI1 : Interp_Index := 0; |
| PIt : Interp; |
| Found : Boolean; |
| |
| begin |
| Found := False; |
| Get_First_Interp (Prefix (Lhs), PI, PIt); |
| |
| while Present (PIt.Typ) loop |
| if Is_Access_Type (PIt.Typ) |
| and then Has_Compatible_Type |
| (Rhs, Designated_Type (PIt.Typ)) |
| then |
| if Found then |
| PIt := |
| Disambiguate (Prefix (Lhs), |
| PI1, PI, Any_Type); |
| |
| if PIt = No_Interp then |
| Error_Msg_N |
| ("ambiguous left-hand side in " |
| & "assignment", Lhs); |
| exit; |
| else |
| Resolve (Prefix (Lhs), PIt.Typ); |
| end if; |
| |
| exit; |
| else |
| Found := True; |
| PI1 := PI; |
| end if; |
| end if; |
| |
| Get_Next_Interp (PI, PIt); |
| end loop; |
| end; |
| |
| else |
| Error_Msg_N |
| ("ambiguous left-hand side in assignment", Lhs); |
| exit; |
| end if; |
| end if; |
| end if; |
| |
| Get_Next_Interp (I, It); |
| end loop; |
| end; |
| |
| if T1 = Any_Type then |
| Error_Msg_N |
| ("no valid types for left-hand side for assignment", Lhs); |
| Kill_Lhs; |
| goto Leave; |
| end if; |
| end if; |
| |
| -- Deal with build-in-place calls for nonlimited types. We don't do this |
| -- later, because resolving the rhs tranforms it incorrectly for build- |
| -- in-place. |
| |
| if Should_Transform_BIP_Assignment (Typ => T1) then |
| |
| -- In certain cases involving user-defined concatenation operators, |
| -- we need to resolve the right-hand side before transforming the |
| -- assignment. |
| |
| case Nkind (Unqual_Conv (Rhs)) is |
| when N_Function_Call => |
| declare |
| Actual : Node_Id := |
| First (Parameter_Associations (Unqual_Conv (Rhs))); |
| Actual_Exp : Node_Id; |
| |
| begin |
| while Present (Actual) loop |
| if Nkind (Actual) = N_Parameter_Association then |
| Actual_Exp := Explicit_Actual_Parameter (Actual); |
| else |
| Actual_Exp := Actual; |
| end if; |
| |
| if Nkind (Actual_Exp) = N_Op_Concat then |
| Resolve (Rhs, T1); |
| exit; |
| end if; |
| |
| Next (Actual); |
| end loop; |
| end; |
| |
| when N_Attribute_Reference |
| | N_Expanded_Name |
| | N_Identifier |
| | N_Op |
| => |
| null; |
| |
| when others => |
| raise Program_Error; |
| end case; |
| |
| Transform_BIP_Assignment (Typ => T1); |
| end if; |
| |
| pragma Assert (not Should_Transform_BIP_Assignment (Typ => T1)); |
| |
| -- The resulting assignment type is T1, so now we will resolve the left |
| -- hand side of the assignment using this determined type. |
| |
| Resolve (Lhs, T1); |
| |
| -- Cases where Lhs is not a variable. In an instance or an inlined body |
| -- no need for further check because assignment was legal in template. |
| |
| if In_Inlined_Body then |
| null; |
| |
| elsif not Is_Variable (Lhs) then |
| |
| -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a |
| -- protected object. |
| |
| declare |
| Ent : Entity_Id; |
| S : Entity_Id; |
| |
| begin |
| if Ada_Version >= Ada_2005 then |
| |
| -- Handle chains of renamings |
| |
| Ent := Lhs; |
| while Nkind (Ent) in N_Has_Entity |
| and then Present (Entity (Ent)) |
| and then Is_Object (Entity (Ent)) |
| and then Present (Renamed_Object (Entity (Ent))) |
| loop |
| Ent := Renamed_Object (Entity (Ent)); |
| end loop; |
| |
| if (Nkind (Ent) = N_Attribute_Reference |
| and then Attribute_Name (Ent) = Name_Priority) |
| |
| -- Renamings of the attribute Priority applied to protected |
| -- objects have been previously expanded into calls to the |
| -- Get_Ceiling run-time subprogram. |
| |
| or else Is_Expanded_Priority_Attribute (Ent) |
| then |
| -- The enclosing subprogram cannot be a protected function |
| |
| S := Current_Scope; |
| while not (Is_Subprogram (S) |
| and then Convention (S) = Convention_Protected) |
| and then S /= Standard_Standard |
| loop |
| S := Scope (S); |
| end loop; |
| |
| if Ekind (S) = E_Function |
| and then Convention (S) = Convention_Protected |
| then |
| Error_Msg_N |
| ("protected function cannot modify its protected " & |
| "object", |
| Lhs); |
| end if; |
| |
| -- Changes of the ceiling priority of the protected object |
| -- are only effective if the Ceiling_Locking policy is in |
| -- effect (AARM D.5.2 (5/2)). |
| |
| if Locking_Policy /= 'C' then |
| Error_Msg_N |
| ("assignment to the attribute PRIORITY has no effect??", |
| Lhs); |
| Error_Msg_N |
| ("\since no Locking_Policy has been specified??", Lhs); |
| end if; |
| |
| goto Leave; |
| end if; |
| end if; |
| end; |
| |
| Diagnose_Non_Variable_Lhs (Lhs); |
| goto Leave; |
| |
| -- Error of assigning to limited type. We do however allow this in |
| -- certain cases where the front end generates the assignments. |
| |
| elsif Is_Limited_Type (T1) |
| and then not Assignment_OK (Lhs) |
| and then not Assignment_OK (Original_Node (Lhs)) |
| then |
| -- CPP constructors can only be called in declarations |
| |
| if Is_CPP_Constructor_Call (Rhs) then |
| Error_Msg_N ("invalid use of 'C'P'P constructor", Rhs); |
| else |
| Error_Msg_N |
| ("left hand of assignment must not be limited type", Lhs); |
| Explain_Limited_Type (T1, Lhs); |
| end if; |
| |
| goto Leave; |
| |
| -- A class-wide type may be a limited view. This illegal case is not |
| -- caught by previous checks. |
| |
| elsif Ekind (T1) = E_Class_Wide_Type and then From_Limited_With (T1) then |
| Error_Msg_NE ("invalid use of limited view of&", Lhs, T1); |
| goto Leave; |
| |
| -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be |
| -- abstract. This is only checked when the assignment Comes_From_Source, |
| -- because in some cases the expander generates such assignments (such |
| -- in the _assign operation for an abstract type). |
| |
| elsif Is_Abstract_Type (T1) and then Comes_From_Source (N) then |
| Error_Msg_N |
| ("target of assignment operation must not be abstract", Lhs); |
| end if; |
| |
| -- Variables which are Part_Of constituents of single protected types |
| -- behave in similar fashion to protected components. Such variables |
| -- cannot be modified by protected functions. |
| |
| if Is_Protected_Part_Of_Constituent (Lhs) and then Within_Function then |
| Error_Msg_N |
| ("protected function cannot modify its protected object", Lhs); |
| end if; |
| |
| -- Resolution may have updated the subtype, in case the left-hand side |
| -- is a private protected component. Use the correct subtype to avoid |
| -- scoping issues in the back-end. |
| |
| T1 := Etype (Lhs); |
| |
| -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete |
| -- type. For example: |
| |
| -- limited with P; |
| -- package Pkg is |
| -- type Acc is access P.T; |
| -- end Pkg; |
| |
| -- with Pkg; use Acc; |
| -- procedure Example is |
| -- A, B : Acc; |
| -- begin |
| -- A.all := B.all; -- ERROR |
| -- end Example; |
| |
| if Nkind (Lhs) = N_Explicit_Dereference |
| and then Ekind (T1) = E_Incomplete_Type |
| then |
| Error_Msg_N ("invalid use of incomplete type", Lhs); |
| Kill_Lhs; |
| goto Leave; |
| end if; |
| |
| -- Now we can complete the resolution of the right hand side |
| |
| Set_Assignment_Type (Lhs, T1); |
| |
| -- If the target of the assignment is an entity of a mutable type and |
| -- the expression is a conditional expression, its alternatives can be |
| -- of different subtypes of the nominal type of the LHS, so they must be |
| -- resolved with the base type, given that their subtype may differ from |
| -- that of the target mutable object. |
| |
| if Is_Entity_Name (Lhs) |
| and then Is_Assignable (Entity (Lhs)) |
| and then Is_Composite_Type (T1) |
| and then not Is_Constrained (Etype (Entity (Lhs))) |
| and then Nkind (Rhs) in N_If_Expression | N_Case_Expression |
| then |
| Resolve (Rhs, Base_Type (T1)); |
| |
| else |
| Resolve (Rhs, T1); |
| end if; |
| |
| -- This is the point at which we check for an unset reference |
| |
| Check_Unset_Reference (Rhs); |
| Check_Unprotected_Access (Lhs, Rhs); |
| |
| -- Remaining steps are skipped if Rhs was syntactically in error |
| |
| if Rhs = Error then |
| Kill_Lhs; |
| goto Leave; |
| end if; |
| |
| T2 := Etype (Rhs); |
| |
| if not Covers (T1, T2) then |
| Wrong_Type (Rhs, Etype (Lhs)); |
| Kill_Lhs; |
| goto Leave; |
| end if; |
| |
| -- Ada 2005 (AI-326): In case of explicit dereference of incomplete |
| -- types, use the non-limited view if available |
| |
| if Nkind (Rhs) = N_Explicit_Dereference |
| and then Is_Tagged_Type (T2) |
| and then Has_Non_Limited_View (T2) |
| then |
| T2 := Non_Limited_View (T2); |
| end if; |
| |
| Set_Assignment_Type (Rhs, T2); |
| |
| if Total_Errors_Detected /= 0 then |
| if No (T1) then |
| T1 := Any_Type; |
| end if; |
| |
| if No (T2) then |
| T2 := Any_Type; |
| end if; |
| end if; |
| |
| if T1 = Any_Type or else T2 = Any_Type then |
| Kill_Lhs; |
| goto Leave; |
| end if; |
| |
| -- If the rhs is class-wide or dynamically tagged, then require the lhs |
| -- to be class-wide. The case where the rhs is a dynamically tagged call |
| -- to a dispatching operation with a controlling access result is |
| -- excluded from this check, since the target has an access type (and |
| -- no tag propagation occurs in that case). |
| |
| if (Is_Class_Wide_Type (T2) |
| or else (Is_Dynamically_Tagged (Rhs) |
| and then not Is_Access_Type (T1))) |
| and then not Is_Class_Wide_Type (T1) |
| then |
| Error_Msg_N ("dynamically tagged expression not allowed!", Rhs); |
| |
| elsif Is_Class_Wide_Type (T1) |
| and then not Is_Class_Wide_Type (T2) |
| and then not Is_Tag_Indeterminate (Rhs) |
| and then not Is_Dynamically_Tagged (Rhs) |
| then |
| Error_Msg_N ("dynamically tagged expression required!", Rhs); |
| end if; |
| |
| -- Propagate the tag from a class-wide target to the rhs when the rhs |
| -- is a tag-indeterminate call. |
| |
| if Is_Tag_Indeterminate (Rhs) then |
| if Is_Class_Wide_Type (T1) then |
| Propagate_Tag (Lhs, Rhs); |
| |
| elsif Nkind (Rhs) = N_Function_Call |
| and then Is_Entity_Name (Name (Rhs)) |
| and then Is_Abstract_Subprogram (Entity (Name (Rhs))) |
| then |
| Error_Msg_N |
| ("call to abstract function must be dispatching", Name (Rhs)); |
| |
| elsif Nkind (Rhs) = N_Qualified_Expression |
| and then Nkind (Expression (Rhs)) = N_Function_Call |
| and then Is_Entity_Name (Name (Expression (Rhs))) |
| and then |
| Is_Abstract_Subprogram (Entity (Name (Expression (Rhs)))) |
| then |
| Error_Msg_N |
| ("call to abstract function must be dispatching", |
| Name (Expression (Rhs))); |
| end if; |
| end if; |
| |
| -- Ada 2005 (AI-385): When the lhs type is an anonymous access type, |
| -- apply an implicit conversion of the rhs to that type to force |
| -- appropriate static and run-time accessibility checks. This applies |
| -- as well to anonymous access-to-subprogram types that are component |
| -- subtypes or formal parameters. |
| |
| if Ada_Version >= Ada_2005 and then Is_Access_Type (T1) then |
| if Is_Local_Anonymous_Access (T1) |
| or else Ekind (T2) = E_Anonymous_Access_Subprogram_Type |
| |
| -- Handle assignment to an Ada 2012 stand-alone object |
| -- of an anonymous access type. |
| |
| or else (Ekind (T1) = E_Anonymous_Access_Type |
| and then Nkind (Associated_Node_For_Itype (T1)) = |
| N_Object_Declaration) |
| |
| then |
| Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs))); |
| Analyze_And_Resolve (Rhs, T1); |
| end if; |
| end if; |
| |
| -- Ada 2005 (AI-231): Assignment to not null variable |
| |
| if Ada_Version >= Ada_2005 |
| and then Can_Never_Be_Null (T1) |
| and then not Assignment_OK (Lhs) |
| then |
| -- Case where we know the right hand side is null |
| |
| if Known_Null (Rhs) then |
| Apply_Compile_Time_Constraint_Error |
| (N => Rhs, |
| Msg => |
| "(Ada 2005) NULL not allowed in null-excluding objects??", |
| Reason => CE_Null_Not_Allowed); |
| |
| -- We still mark this as a possible modification, that's necessary |
| -- to reset Is_True_Constant, and desirable for xref purposes. |
| |
| Note_Possible_Modification (Lhs, Sure => True); |
| goto Leave; |
| |
| -- If we know the right hand side is non-null, then we convert to the |
| -- target type, since we don't need a run time check in that case. |
| |
| elsif not Can_Never_Be_Null (T2) then |
| Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs))); |
| Analyze_And_Resolve (Rhs, T1); |
| end if; |
| end if; |
| |
| if Is_Scalar_Type (T1) then |
| declare |
| |
| function Omit_Range_Check_For_Streaming return Boolean; |
| -- Return True if this assignment statement is the expansion of |
| -- a Some_Scalar_Type'Read procedure call such that all conditions |
| -- of 13.3.2(35)'s "no check is made" rule are met. |
| |
| ------------------------------------ |
| -- Omit_Range_Check_For_Streaming -- |
| ------------------------------------ |
| |
| function Omit_Range_Check_For_Streaming return Boolean is |
| begin |
| -- Have we got an implicitly generated assignment to a |
| -- component of a composite object? If not, return False. |
| |
| if Comes_From_Source (N) |
| or else Serious_Errors_Detected > 0 |
| or else Nkind (Lhs) |
| not in N_Selected_Component | N_Indexed_Component |
| then |
| return False; |
| end if; |
| |
| declare |
| Pref : constant Node_Id := Prefix (Lhs); |
| begin |
| -- Are we in the implicitly-defined Read subprogram |
| -- for a composite type, reading the value of a scalar |
| -- component from the stream? If not, return False. |
| |
| if Nkind (Pref) /= N_Identifier |
| or else not Is_TSS (Scope (Entity (Pref)), TSS_Stream_Read) |
| then |
| return False; |
| end if; |
| |
| -- Return False if Default_Value or Default_Component_Value |
| -- aspect applies. |
| |
| if Has_Default_Aspect (Etype (Lhs)) |
| or else Has_Default_Aspect (Etype (Pref)) |
| then |
| return False; |
| |
| -- Are we assigning to a record component (as opposed to |
| -- an array component)? |
| |
| elsif Nkind (Lhs) = N_Selected_Component then |
| |
| -- Are we assigning to a nondiscriminant component |
| -- that lacks a default initial value expression? |
| -- If so, return True. |
| |
| declare |
| Comp_Id : constant Entity_Id := |
| Original_Record_Component |
| (Entity (Selector_Name (Lhs))); |
| begin |
| if Ekind (Comp_Id) = E_Component |
| and then Nkind (Parent (Comp_Id)) |
| = N_Component_Declaration |
| and then |
| not Present (Expression (Parent (Comp_Id))) |
| then |
| return True; |
| end if; |
| return False; |
| end; |
| |
| -- We are assigning to a component of an array |
| -- (and we tested for both Default_Value and |
| -- Default_Component_Value above), so return True. |
| |
| else |
| pragma Assert (Nkind (Lhs) = N_Indexed_Component); |
| return True; |
| end if; |
| end; |
| end Omit_Range_Check_For_Streaming; |
| |
| begin |
| if not Omit_Range_Check_For_Streaming then |
| Apply_Scalar_Range_Check (Rhs, Etype (Lhs)); |
| end if; |
| end; |
| |
| -- For array types, verify that lengths match. If the right hand side |
| -- is a function call that has been inlined, the assignment has been |
| -- rewritten as a block, and the constraint check will be applied to the |
| -- assignment within the block. |
| |
| elsif Is_Array_Type (T1) |
| and then (Nkind (Rhs) /= N_Type_Conversion |
| or else Is_Constrained (Etype (Rhs))) |
| and then (Nkind (Rhs) /= N_Function_Call |
| or else Nkind (N) /= N_Block_Statement) |
| then |
| -- Assignment verifies that the length of the Lhs and Rhs are equal, |
| -- but of course the indexes do not have to match. If the right-hand |
| -- side is a type conversion to an unconstrained type, a length check |
| -- is performed on the expression itself during expansion. In rare |
| -- cases, the redundant length check is computed on an index type |
| -- with a different representation, triggering incorrect code in the |
| -- back end. |
| |
| Apply_Length_Check_On_Assignment (Rhs, Etype (Lhs), Lhs); |
| |
| else |
| -- Discriminant checks are applied in the course of expansion |
| |
| null; |
| end if; |
| |
| -- Note: modifications of the Lhs may only be recorded after |
| -- checks have been applied. |
| |
| Note_Possible_Modification (Lhs, Sure => True); |
| |
| -- ??? a real accessibility check is needed when ??? |
| |
| -- Post warning for redundant assignment or variable to itself |
| |
| if Warn_On_Redundant_Constructs |
| |
| -- We only warn for source constructs |
| |
| and then Comes_From_Source (N) |
| |
| -- Where the object is the same on both sides |
| |
| and then Same_Object (Lhs, Original_Node (Rhs)) |
| |
| -- But exclude the case where the right side was an operation that |
| -- got rewritten (e.g. JUNK + K, where K was known to be zero). We |
| -- don't want to warn in such a case, since it is reasonable to write |
| -- such expressions especially when K is defined symbolically in some |
| -- other package. |
| |
| and then Nkind (Original_Node (Rhs)) not in N_Op |
| then |
| if Nkind (Lhs) in N_Has_Entity then |
| Error_Msg_NE -- CODEFIX |
| ("?r?useless assignment of & to itself!", N, Entity (Lhs)); |
| else |
| Error_Msg_N -- CODEFIX |
| ("?r?useless assignment of object to itself!", N); |
| end if; |
| end if; |
| |
| -- Check for non-allowed composite assignment |
| |
| if not Support_Composite_Assign_On_Target |
| and then (Is_Array_Type (T1) or else Is_Record_Type (T1)) |
| and then (not Has_Size_Clause (T1) |
| or else Esize (T1) > Ttypes.System_Max_Integer_Size) |
| then |
| Error_Msg_CRT ("composite assignment", N); |
| end if; |
| |
| -- Check elaboration warning for left side if not in elab code |
| |
| if Legacy_Elaboration_Checks |
| and not In_Subprogram_Or_Concurrent_Unit |
| then |
| Check_Elab_Assign (Lhs); |
| end if; |
| |
| -- Save the scenario for later examination by the ABE Processing phase |
| |
| Record_Elaboration_Scenario (N); |
| |
| -- Set Referenced_As_LHS if appropriate. We only set this flag if the |
| -- assignment is a source assignment in the extended main source unit. |
| -- We are not interested in any reference information outside this |
| -- context, or in compiler generated assignment statements. |
| |
| if Comes_From_Source (N) |
| and then In_Extended_Main_Source_Unit (Lhs) |
| then |
| Set_Referenced_Modified (Lhs, Out_Param => False); |
| end if; |
| |
| -- RM 7.3.2 (12/3): An assignment to a view conversion (from a type to |
| -- one of its ancestors) requires an invariant check. Apply check only |
| -- if expression comes from source, otherwise it will be applied when |
| -- value is assigned to source entity. This is not done in GNATprove |
| -- mode, as GNATprove handles invariant checks itself. |
| |
| if Nkind (Lhs) = N_Type_Conversion |
| and then Has_Invariants (Etype (Expression (Lhs))) |
| and then Comes_From_Source (Expression (Lhs)) |
| and then not GNATprove_Mode |
| then |
| Insert_After (N, Make_Invariant_Call (Expression (Lhs))); |
| end if; |
| |
| -- Final step. If left side is an entity, then we may be able to reset |
| -- the current tracked values to new safe values. We only have something |
| -- to do if the left side is an entity name, and expansion has not |
| -- modified the node into something other than an assignment, and of |
| -- course we only capture values if it is safe to do so. |
| |
| if Is_Entity_Name (Lhs) |
| and then Nkind (N) = N_Assignment_Statement |
| then |
| declare |
| Ent : constant Entity_Id := Entity (Lhs); |
| |
| begin |
| if Safe_To_Capture_Value (N, Ent) then |
| |
| -- If simple variable on left side, warn if this assignment |
| -- blots out another one (rendering it useless). We only do |
| -- this for source assignments, otherwise we can generate bogus |
| -- warnings when an assignment is rewritten as another |
| -- assignment, and gets tied up with itself. |
| |
| -- We also omit the warning if the RHS includes target names, |
| -- that is to say the Ada 2022 "@" that denotes an instance of |
| -- the LHS, which indicates that the current value is being |
| -- used. Note that this implicit reference to the entity on |
| -- the RHS is not treated as a source reference. |
| |
| -- There may have been a previous reference to a component of |
| -- the variable, which in general removes the Last_Assignment |
| -- field of the variable to indicate a relevant use of the |
| -- previous assignment. However, if the assignment is to a |
| -- subcomponent the reference may not have registered, because |
| -- it is not possible to determine whether the context is an |
| -- assignment. In those cases we generate a Deferred_Reference, |
| -- to be used at the end of compilation to generate the right |
| -- kind of reference, and we suppress a potential warning for |
| -- a useless assignment, which might be premature. This may |
| -- lose a warning in rare cases, but seems preferable to a |
| -- misleading warning. |
| |
| if Warn_On_Modified_Unread |
| and then Is_Assignable (Ent) |
| and then Comes_From_Source (N) |
| and then In_Extended_Main_Source_Unit (Ent) |
| and then not Has_Deferred_Reference (Ent) |
| and then not Has_Target_Names (N) |
| then |
| Warn_On_Useless_Assignment (Ent, N); |
| end if; |
| |
| -- If we are assigning an access type and the left side is an |
| -- entity, then make sure that the Is_Known_[Non_]Null flags |
| -- properly reflect the state of the entity after assignment. |
| |
| if Is_Access_Type (T1) then |
| if Known_Non_Null (Rhs) then |
| Set_Is_Known_Non_Null (Ent, True); |
| |
| elsif Known_Null (Rhs) |
| and then not Can_Never_Be_Null (Ent) |
| then |
| Set_Is_Known_Null (Ent, True); |
| |
| else |
| Set_Is_Known_Null (Ent, False); |
| |
| if not Can_Never_Be_Null (Ent) then |
| Set_Is_Known_Non_Null (Ent, False); |
| end if; |
| end if; |
| |
| -- For discrete types, we may be able to set the current value |
| -- if the value is known at compile time. |
| |
| elsif Is_Discrete_Type (T1) |
| and then Compile_Time_Known_Value (Rhs) |
| then |
| Set_Current_Value (Ent, Rhs); |
| else |
| Set_Current_Value (Ent, Empty); |
| end if; |
| |
| -- If not safe to capture values, kill them |
| |
| else |
| Kill_Lhs; |
| end if; |
| end; |
| end if; |
| |
| -- If assigning to an object in whole or in part, note location of |
| -- assignment in case no one references value. We only do this for |
| -- source assignments, otherwise we can generate bogus warnings when an |
| -- assignment is rewritten as another assignment, and gets tied up with |
| -- itself. |
| |
| declare |
| Ent : constant Entity_Id := Get_Enclosing_Object (Lhs); |
| begin |
| if Present (Ent) |
| and then Safe_To_Capture_Value (N, Ent) |
| and then Nkind (N) = N_Assignment_Statement |
| and then Warn_On_Modified_Unread |
| and then Is_Assignable (Ent) |
| and then Comes_From_Source (N) |
| and then In_Extended_Main_Source_Unit (Ent) |
| then |
| Set_Last_Assignment (Ent, Lhs); |
| end if; |
| end; |
| |
| Analyze_Dimension (N); |
| |
| <<Leave>> |
| Restore_Ghost_Region (Saved_GM, Saved_IGR); |
| |
| -- If the right-hand side contains target names, expansion has been |
| -- disabled to prevent expansion that might move target names out of |
| -- the context of the assignment statement. Restore the expander mode |
| -- now so that assignment statement can be properly expanded. |
| |
| if Nkind (N) = N_Assignment_Statement then |
| if Has_Target_Names (N) then |
| Expander_Mode_Restore; |
| Full_Analysis := Save_Full_Analysis; |
| Current_Assignment := Empty; |
| end if; |
| |
| pragma Assert (not Should_Transform_BIP_Assignment (Typ => T1)); |
| end if; |
| end Analyze_Assignment; |
| |
| ----------------------------- |
| -- Analyze_Block_Statement -- |
| ----------------------------- |
| |
| procedure Analyze_Block_Statement (N : Node_Id) is |
| procedure Install_Return_Entities (Scop : Entity_Id); |
| -- Install all entities of return statement scope Scop in the visibility |
| -- chain except for the return object since its entity is reused in a |
| -- renaming. |
| |
| ----------------------------- |
| -- Install_Return_Entities -- |
| ----------------------------- |
| |
| procedure Install_Return_Entities (Scop : Entity_Id) is |
| Id : Entity_Id; |
| |
| begin |
| Id := First_Entity (Scop); |
| while Present (Id) loop |
| |
| -- Do not install the return object |
| |
| if Ekind (Id) not in E_Constant | E_Variable |
| or else not Is_Return_Object (Id) |
| then |
| Install_Entity (Id); |
| end if; |
| |
| Next_Entity (Id); |
| end loop; |
| end Install_Return_Entities; |
| |
| -- Local constants and variables |
| |
| Decls : constant List_Id := Declarations (N); |
| Id : constant Node_Id := Identifier (N); |
| HSS : constant Node_Id := Handled_Statement_Sequence (N); |
| |
| Is_BIP_Return_Statement : Boolean; |
| |
| -- Start of processing for Analyze_Block_Statement |
| |
| begin |
| -- If no handled statement sequence is present, things are really messed |
| -- up, and we just return immediately (defence against previous errors). |
| |
| if No (HSS) then |
| Check_Error_Detected; |
| return; |
| end if; |
| |
| -- Detect whether the block is actually a rewritten return statement of |
| -- a build-in-place function. |
| |
| Is_BIP_Return_Statement := |
| Present (Id) |
| and then Present (Entity (Id)) |
| and then Ekind (Entity (Id)) = E_Return_Statement |
| and then Is_Build_In_Place_Function |
| (Return_Applies_To (Entity (Id))); |
| |
| -- Normal processing with HSS present |
| |
| declare |
| EH : constant List_Id := Exception_Handlers (HSS); |
| Ent : Entity_Id := Empty; |
| S : Entity_Id; |
| |
| Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count; |
| -- Recursively save value of this global, will be restored on exit |
| |
| begin |
| -- Initialize unblocked exit count for statements of begin block |
| -- plus one for each exception handler that is present. |
| |
| Unblocked_Exit_Count := 1; |
| |
| if Present (EH) then |
| Unblocked_Exit_Count := Unblocked_Exit_Count + List_Length (EH); |
| end if; |
| |
| -- If a label is present analyze it and mark it as referenced |
| |
| if Present (Id) then |
| Analyze (Id); |
| Ent := Entity (Id); |
| |
| -- An error defense. If we have an identifier, but no entity, then |
| -- something is wrong. If previous errors, then just remove the |
| -- identifier and continue, otherwise raise an exception. |
| |
| if No (Ent) then |
| Check_Error_Detected; |
| Set_Identifier (N, Empty); |
| |
| else |
| if Ekind (Ent) = E_Label then |
| Reinit_Field_To_Zero (Ent, F_Enclosing_Scope); |
| end if; |
| |
| Mutate_Ekind (Ent, E_Block); |
| Generate_Reference (Ent, N, ' '); |
| Generate_Definition (Ent); |
| |
| if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then |
| Set_Label_Construct (Parent (Ent), N); |
| end if; |
| end if; |
| end if; |
| |
| -- If no entity set, create a label entity |
| |
| if No (Ent) then |
| Ent := New_Internal_Entity (E_Block, Current_Scope, Sloc (N), 'B'); |
| Set_Identifier (N, New_Occurrence_Of (Ent, Sloc (N))); |
| Set_Parent (Ent, N); |
| end if; |
| |
| Set_Etype (Ent, Standard_Void_Type); |
| Set_Block_Node (Ent, Identifier (N)); |
| Push_Scope (Ent); |
| |
| -- The block served as an extended return statement. Ensure that any |
| -- entities created during the analysis and expansion of the return |
| -- object declaration are once again visible. |
| |
| if Is_BIP_Return_Statement then |
| Install_Return_Entities (Ent); |
| end if; |
| |
| if Present (Decls) then |
| Analyze_Declarations (Decls); |
| Check_Completion; |
| Inspect_Deferred_Constant_Completion (Decls); |
| end if; |
| |
| Analyze (HSS); |
| Process_End_Label (HSS, 'e', Ent); |
| |
| -- If exception handlers are present, then we indicate that enclosing |
| -- scopes contain a block with handlers. We only need to mark non- |
| -- generic scopes. |
| |
| if Present (EH) then |
| S := Scope (Ent); |
| loop |
| Set_Has_Nested_Block_With_Handler (S); |
| exit when Is_Overloadable (S) |
| or else Ekind (S) = E_Package |
| or else Is_Generic_Unit (S); |
| S := Scope (S); |
| end loop; |
| end if; |
| |
| Check_References (Ent); |
| Update_Use_Clause_Chain; |
| End_Scope; |
| |
| if Unblocked_Exit_Count = 0 then |
| Unblocked_Exit_Count := Save_Unblocked_Exit_Count; |
| Check_Unreachable_Code (N); |
| else |
| Unblocked_Exit_Count := Save_Unblocked_Exit_Count; |
| end if; |
| end; |
| end Analyze_Block_Statement; |
| |
| -------------------------------- |
| -- Analyze_Compound_Statement -- |
| -------------------------------- |
| |
| procedure Analyze_Compound_Statement (N : Node_Id) is |
| begin |
| Analyze_List (Actions (N)); |
| end Analyze_Compound_Statement; |
| |
| ---------------------------- |
| -- Analyze_Case_Statement -- |
| ---------------------------- |
| |
| procedure Analyze_Case_Statement (N : Node_Id) is |
| Exp : constant Node_Id := Expression (N); |
| |
| Statements_Analyzed : Boolean := False; |
| -- Set True if at least some statement sequences get analyzed. If False |
| -- on exit, means we had a serious error that prevented full analysis of |
| -- the case statement, and as a result it is not a good idea to output |
| -- warning messages about unreachable code. |
| |
| Is_General_Case_Statement : Boolean := False; |
| -- Set True (later) if type of case expression is not discrete |
| |
| procedure Non_Static_Choice_Error (Choice : Node_Id); |
| -- Error routine invoked by the generic instantiation below when the |
| -- case statement has a non static choice. |
| |
| procedure Process_Statements (Alternative : Node_Id); |
| -- Analyzes the statements associated with a case alternative. Needed |
| -- by instantiation below. |
| |
| package Analyze_Case_Choices is new |
| Generic_Analyze_Choices |
| (Process_Associated_Node => Process_Statements); |
| use Analyze_Case_Choices; |
| -- Instantiation of the generic choice analysis package |
| |
| package Check_Case_Choices is new |
| Generic_Check_Choices |
| (Process_Empty_Choice => No_OP, |
| Process_Non_Static_Choice => Non_Static_Choice_Error, |
| Process_Associated_Node => No_OP); |
| use Check_Case_Choices; |
| -- Instantiation of the generic choice processing package |
| |
| ----------------------------- |
| -- Non_Static_Choice_Error -- |
| ----------------------------- |
| |
| procedure Non_Static_Choice_Error (Choice : Node_Id) is |
| begin |
| Flag_Non_Static_Expr |
| ("choice given in case statement is not static!", Choice); |
| end Non_Static_Choice_Error; |
| |
| ------------------------ |
| -- Process_Statements -- |
| ------------------------ |
| |
| procedure Process_Statements (Alternative : Node_Id) is |
| Choices : constant List_Id := Discrete_Choices (Alternative); |
| Ent : Entity_Id; |
| |
| begin |
| if Is_General_Case_Statement then |
| return; |
| -- Processing deferred in this case; decls associated with |
| -- pattern match bindings don't exist yet. |
| end if; |
| |
| Unblocked_Exit_Count := Unblocked_Exit_Count + 1; |
| Statements_Analyzed := True; |
| |
| -- An interesting optimization. If the case statement expression |
| -- is a simple entity, then we can set the current value within an |
| -- alternative if the alternative has one possible value. |
| |
| -- case N is |
| -- when 1 => alpha |
| -- when 2 | 3 => beta |
| -- when others => gamma |
| |
| -- Here we know that N is initially 1 within alpha, but for beta and |
| -- gamma, we do not know anything more about the initial value. |
| |
| if Is_Entity_Name (Exp) then |
| Ent := Entity (Exp); |
| |
| if Is_Object (Ent) then |
| if List_Length (Choices) = 1 |
| and then Nkind (First (Choices)) in N_Subexpr |
| and then Compile_Time_Known_Value (First (Choices)) |
| then |
| Set_Current_Value (Entity (Exp), First (Choices)); |
| end if; |
| |
| Analyze_Statements (Statements (Alternative)); |
| |
| -- After analyzing the case, set the current value to empty |
| -- since we won't know what it is for the next alternative |
| -- (unless reset by this same circuit), or after the case. |
| |
| Set_Current_Value (Entity (Exp), Empty); |
| return; |
| end if; |
| end if; |
| |
| -- Case where expression is not an entity name of an object |
| |
| Analyze_Statements (Statements (Alternative)); |
| end Process_Statements; |
| |
| -- Local variables |
| |
| Exp_Type : Entity_Id; |
| Exp_Btype : Entity_Id; |
| |
| Others_Present : Boolean; |
| -- Indicates if Others was present |
| |
| Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count; |
| -- Recursively save value of this global, will be restored on exit |
| |
| -- Start of processing for Analyze_Case_Statement |
| |
| begin |
| Analyze (Exp); |
| |
| -- The expression must be of any discrete type. In rare cases, the |
| -- expander constructs a case statement whose expression has a private |
| -- type whose full view is discrete. This can happen when generating |
| -- a stream operation for a variant type after the type is frozen, |
| -- when the partial of view of the type of the discriminant is private. |
| -- In that case, use the full view to analyze case alternatives. |
| |
| if not Is_Overloaded (Exp) |
| and then not Comes_From_Source (N) |
| and then Is_Private_Type (Etype (Exp)) |
| and then Present (Full_View (Etype (Exp))) |
| and then Is_Discrete_Type (Full_View (Etype (Exp))) |
| then |
| Resolve (Exp); |
| Exp_Type := Full_View (Etype (Exp)); |
| |
| -- For Ada, overloading might be ok because subsequently filtering |
| -- out non-discretes may resolve the ambiguity. |
| -- But GNAT extensions allow casing on non-discretes. |
| |
| elsif Extensions_Allowed and then Is_Overloaded (Exp) then |
| |
| -- It would be nice if we could generate all the right error |
| -- messages by calling "Resolve (Exp, Any_Type);" in the |
| -- same way that they are generated a few lines below by the |
| -- call "Analyze_And_Resolve (Exp, Any_Discrete);". |
| -- Unfortunately, Any_Type and Any_Discrete are not treated |
| -- consistently (specifically, by Sem_Type.Covers), so that |
| -- doesn't work. |
| |
| Error_Msg_N |
| ("selecting expression of general case statement is ambiguous", |
| Exp); |
| return; |
| |
| -- Check for a GNAT-extension "general" case statement (i.e., one where |
| -- the type of the selecting expression is not discrete). |
| |
| elsif Extensions_Allowed |
| and then not Is_Discrete_Type (Etype (Exp)) |
| then |
| Resolve (Exp, Etype (Exp)); |
| Exp_Type := Etype (Exp); |
| Is_General_Case_Statement := True; |
| else |
| Analyze_And_Resolve (Exp, Any_Discrete); |
| Exp_Type := Etype (Exp); |
| end if; |
| |
| Check_Unset_Reference (Exp); |
| Exp_Btype := Base_Type (Exp_Type); |
| |
| -- The expression must be of a discrete type which must be determinable |
| -- independently of the context in which the expression occurs, but |
| -- using the fact that the expression must be of a discrete type. |
| -- Moreover, the type this expression must not be a character literal |
| -- (which is always ambiguous) or, for Ada-83, a generic formal type. |
| |
| -- If error already reported by Resolve, nothing more to do |
| |
| if Exp_Btype = Any_Discrete or else Exp_Btype = Any_Type then |
| return; |
| |
| elsif Exp_Btype = Any_Character then |
| Error_Msg_N |
| ("character literal as case expression is ambiguous", Exp); |
| return; |
| |
| elsif Ada_Version = Ada_83 |
| and then (Is_Generic_Type (Exp_Btype) |
| or else Is_Generic_Type (Root_Type (Exp_Btype))) |
| then |
| Error_Msg_N |
| ("(Ada 83) case expression cannot be of a generic type", Exp); |
| return; |
| |
| elsif not Extensions_Allowed |
| and then not Is_Discrete_Type (Exp_Type) |
| then |
| Error_Msg_N |
| ("expression in case statement must be of a discrete_Type", Exp); |
| return; |
| end if; |
| |
| -- If the case expression is a formal object of mode in out, then treat |
| -- it as having a nonstatic subtype by forcing use of the base type |
| -- (which has to get passed to Check_Case_Choices below). Also use base |
| -- type when the case expression is parenthesized. |
| |
| if Paren_Count (Exp) > 0 |
| or else (Is_Entity_Name (Exp) |
| and then Ekind (Entity (Exp)) = E_Generic_In_Out_Parameter) |
| then |
| Exp_Type := Exp_Btype; |
| end if; |
| |
| -- Call instantiated procedures to analyze and check discrete choices |
| |
| Unblocked_Exit_Count := 0; |
| |
| Analyze_Choices (Alternatives (N), Exp_Type); |
| Check_Choices (N, Alternatives (N), Exp_Type, Others_Present); |
| |
| if Is_General_Case_Statement then |
| -- Work normally done in Process_Statements was deferred; do that |
| -- deferred work now that Check_Choices has had a chance to create |
| -- any needed pattern-match-binding declarations. |
| declare |
| Alt : Node_Id := First (Alternatives (N)); |
| begin |
| while Present (Alt) loop |
| Unblocked_Exit_Count := Unblocked_Exit_Count + 1; |
| Analyze_Statements (Statements (Alt)); |
| Next (Alt); |
| end loop; |
| end; |
| end if; |
| |
| if Exp_Type = Universal_Integer and then not Others_Present then |
| Error_Msg_N ("case on universal integer requires OTHERS choice", Exp); |
| end if; |
| |
| -- If all our exits were blocked by unconditional transfers of control, |
| -- then the entire CASE statement acts as an unconditional transfer of |
| -- control, so treat it like one, and check unreachable code. Skip this |
| -- test if we had serious errors preventing any statement analysis. |
| |
| if Unblocked_Exit_Count = 0 and then Statements_Analyzed then |
| Unblocked_Exit_Count := Save_Unblocked_Exit_Count; |
| Check_Unreachable_Code (N); |
| else |
| Unblocked_Exit_Count := Save_Unblocked_Exit_Count; |
| end if; |
| |
| -- If the expander is active it will detect the case of a statically |
| -- determined single alternative and remove warnings for the case, but |
| -- if we are not doing expansion, that circuit won't be active. Here we |
| -- duplicate the effect of removing warnings in the same way, so that |
| -- we will get the same set of warnings in -gnatc mode. |
| |
| if not Expander_Active |
| and then Compile_Time_Known_Value (Expression (N)) |
| and then Serious_Errors_Detected = 0 |
| then |
| declare |
| Chosen : constant Node_Id := Find_Static_Alternative (N); |
| Alt : Node_Id; |
| |
| begin |
| Alt := First (Alternatives (N)); |
| while Present (Alt) loop |
| if Alt /= Chosen then |
| Remove_Warning_Messages (Statements (Alt)); |
| end if; |
| |
| Next (Alt); |
| end loop; |
| end; |
| end if; |
| end Analyze_Case_Statement; |
| |
| ---------------------------- |
| -- Analyze_Exit_Statement -- |
| ---------------------------- |
| |
| -- If the exit includes a name, it must be the name of a currently open |
| -- loop. Otherwise there must be an innermost open loop on the stack, to |
| -- which the statement implicitly refers. |
| |
| -- Additionally, in SPARK mode: |
| |
| -- The exit can only name the closest enclosing loop; |
| |
| -- An exit with a when clause must be directly contained in a loop; |
| |
| -- An exit without a when clause must be directly contained in an |
| -- if-statement with no elsif or else, which is itself directly contained |
| -- in a loop. The exit must be the last statement in the if-statement. |
| |
| procedure Analyze_Exit_Statement (N : Node_Id) is |
| Target : constant Node_Id := Name (N); |
| Cond : constant Node_Id := Condition (N); |
| Scope_Id : Entity_Id := Empty; -- initialize to prevent warning |
| U_Name : Entity_Id; |
| Kind : Entity_Kind; |
| |
| begin |
| if No (Cond) then |
| Check_Unreachable_Code (N); |
| end if; |
| |
| if Present (Target) then |
| Analyze (Target); |
| U_Name := Entity (Target); |
| |
| if not In_Open_Scopes (U_Name) or else Ekind (U_Name) /= E_Loop then |
| Error_Msg_N ("invalid loop name in exit statement", N); |
| return; |
| |
| else |
| Set_Has_Exit (U_Name); |
| end if; |
| |
| else |
| U_Name := Empty; |
| end if; |
| |
| for J in reverse 0 .. Scope_Stack.Last loop |
| Scope_Id := Scope_Stack.Table (J).Entity; |
| Kind := Ekind (Scope_Id); |
| |
| if Kind = E_Loop and then (No (Target) or else Scope_Id = U_Name) then |
| Set_Has_Exit (Scope_Id); |
| exit; |
| |
| elsif Kind = E_Block |
| or else Kind = E_Loop |
| or else Kind = E_Return_Statement |
| then |
| null; |
| |
| else |
| Error_Msg_N |
| ("cannot exit from program unit or accept statement", N); |
| return; |
| end if; |
| end loop; |
| |
| -- Verify that if present the condition is a Boolean expression |
| |
| if Present (Cond) then |
| Analyze_And_Resolve (Cond, Any_Boolean); |
| Check_Unset_Reference (Cond); |
| end if; |
| |
| -- Chain exit statement to associated loop entity |
| |
| Set_Next_Exit_Statement (N, First_Exit_Statement (Scope_Id)); |
| Set_First_Exit_Statement (Scope_Id, N); |
| |
| -- Since the exit may take us out of a loop, any previous assignment |
| -- statement is not useless, so clear last assignment indications. It |
| -- is OK to keep other current values, since if the exit statement |
| -- does not exit, then the current values are still valid. |
| |
| Kill_Current_Values (Last_Assignment_Only => True); |
| end Analyze_Exit_Statement; |
| |
| ---------------------------- |
| -- Analyze_Goto_Statement -- |
| ---------------------------- |
| |
| procedure Analyze_Goto_Statement (N : Node_Id) is |
| Label : constant Node_Id := Name (N); |
| Scope_Id : Entity_Id; |
| Label_Scope : Entity_Id; |
| Label_Ent : Entity_Id; |
| |
| begin |
| -- Actual semantic checks |
| |
| Check_Unreachable_Code (N); |
| Kill_Current_Values (Last_Assignment_Only => True); |
| |
| Analyze (Label); |
| Label_Ent := Entity (Label); |
| |
| -- Ignore previous error |
| |
| if Label_Ent = Any_Id then |
| Check_Error_Detected; |
| return; |
| |
| -- We just have a label as the target of a goto |
| |
| elsif Ekind (Label_Ent) /= E_Label then |
| Error_Msg_N ("target of goto statement must be a label", Label); |
| return; |
| |
| -- Check that the target of the goto is reachable according to Ada |
| -- scoping rules. Note: the special gotos we generate for optimizing |
| -- local handling of exceptions would violate these rules, but we mark |
| -- such gotos as analyzed when built, so this code is never entered. |
| |
| elsif not Reachable (Label_Ent) then |
| Error_Msg_N ("target of goto statement is not reachable", Label); |
| return; |
| end if; |
| |
| -- Here if goto passes initial validity checks |
| |
| Label_Scope := Enclosing_Scope (Label_Ent); |
| |
| for J in reverse 0 .. Scope_Stack.Last loop |
| Scope_Id := Scope_Stack.Table (J).Entity; |
| |
| if Label_Scope = Scope_Id |
| or else Ekind (Scope_Id) not in |
| E_Block | E_Loop | E_Return_Statement |
| then |
| if Scope_Id /= Label_Scope then |
| Error_Msg_N |
| ("cannot exit from program unit or accept statement", N); |
| end if; |
| |
| return; |
| end if; |
| end loop; |
| |
| raise Program_Error; |
| end Analyze_Goto_Statement; |
| |
| --------------------------------- |
| -- Analyze_Goto_When_Statement -- |
| --------------------------------- |
| |
| procedure Analyze_Goto_When_Statement (N : Node_Id) is |
| begin |
| -- Verify the condition is a Boolean expression |
| |
| Analyze_And_Resolve (Condition (N), Any_Boolean); |
| Check_Unset_Reference (Condition (N)); |
| end Analyze_Goto_When_Statement; |
| |
| -------------------------- |
| -- Analyze_If_Statement -- |
| -------------------------- |
| |
| -- A special complication arises in the analysis of if statements |
| |
| -- The expander has circuitry to completely delete code that it can tell |
| -- will not be executed (as a result of compile time known conditions). In |
| -- the analyzer, we ensure that code that will be deleted in this manner |
| -- is analyzed but not expanded. This is obviously more efficient, but |
| -- more significantly, difficulties arise if code is expanded and then |
| -- eliminated (e.g. exception table entries disappear). Similarly, itypes |
| -- generated in deleted code must be frozen from start, because the nodes |
| -- on which they depend will not be available at the freeze point. |
| |
| procedure Analyze_If_Statement (N : Node_Id) is |
| Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count; |
| -- Recursively save value of this global, will be restored on exit |
| |
| Save_In_Deleted_Code : Boolean := In_Deleted_Code; |
| |
| Del : Boolean := False; |
| -- This flag gets set True if a True condition has been found, which |
| -- means that remaining ELSE/ELSIF parts are deleted. |
| |
| procedure Analyze_Cond_Then (Cnode : Node_Id); |
| -- This is applied to either the N_If_Statement node itself or to an |
| -- N_Elsif_Part node. It deals with analyzing the condition and the THEN |
| -- statements associated with it. |
| |
| ----------------------- |
| -- Analyze_Cond_Then -- |
| ----------------------- |
| |
| procedure Analyze_Cond_Then (Cnode : Node_Id) is |
| Cond : constant Node_Id := Condition (Cnode); |
| Tstm : constant List_Id := Then_Statements (Cnode); |
| |
| begin |
| Unblocked_Exit_Count := Unblocked_Exit_Count + 1; |
| Analyze_And_Resolve (Cond, Any_Boolean); |
| Check_Unset_Reference (Cond); |
| Set_Current_Value_Condition (Cnode); |
| |
| -- If already deleting, then just analyze then statements |
| |
| if Del then |
| Analyze_Statements (Tstm); |
| |
| -- Compile time known value, not deleting yet |
| |
| elsif Compile_Time_Known_Value (Cond) then |
| Save_In_Deleted_Code := In_Deleted_Code; |
| |
| -- If condition is True, then analyze the THEN statements and set |
| -- no expansion for ELSE and ELSIF parts. |
| |
| if Is_True (Expr_Value (Cond)) then |
| Analyze_Statements (Tstm); |
| Del := True; |
| Expander_Mode_Save_And_Set (False); |
| In_Deleted_Code := True; |
| |
| -- If condition is False, analyze THEN with expansion off |
| |
| else pragma Assert (Is_False (Expr_Value (Cond))); |
| Expander_Mode_Save_And_Set (False); |
| In_Deleted_Code := True; |
| Analyze_Statements (Tstm); |
| Expander_Mode_Restore; |
| In_Deleted_Code := Save_In_Deleted_Code; |
| end if; |
| |
| -- Not known at compile time, not deleting, normal analysis |
| |
| else |
| Analyze_Statements (Tstm); |
| end if; |
| end Analyze_Cond_Then; |
| |
| -- Local variables |
| |
| E : Node_Id; |
| -- For iterating over elsif parts |
| |
| -- Start of processing for Analyze_If_Statement |
| |
| begin |
| -- Initialize exit count for else statements. If there is no else part, |
| -- this count will stay non-zero reflecting the fact that the uncovered |
| -- else case is an unblocked exit. |
| |
| Unblocked_Exit_Count := 1; |
| Analyze_Cond_Then (N); |
| |
| -- Now to analyze the elsif parts if any are present |
| |
| if Present (Elsif_Parts (N)) then |
| E := First (Elsif_Parts (N)); |
| while Present (E) loop |
| Analyze_Cond_Then (E); |
| Next (E); |
| end loop; |
| end if; |
| |
| if Present (Else_Statements (N)) then |
| Analyze_Statements (Else_Statements (N)); |
| end if; |
| |
| -- If all our exits were blocked by unconditional transfers of control, |
| -- then the entire IF statement acts as an unconditional transfer of |
| -- control, so treat it like one, and check unreachable code. |
| |
| if Unblocked_Exit_Count = 0 then |
| Unblocked_Exit_Count := Save_Unblocked_Exit_Count; |
| Check_Unreachable_Code (N); |
| else |
| Unblocked_Exit_Count := Save_Unblocked_Exit_Count; |
| end if; |
| |
| if Del then |
| Expander_Mode_Restore; |
| In_Deleted_Code := Save_In_Deleted_Code; |
| end if; |
| |
| if not Expander_Active |
| and then Compile_Time_Known_Value (Condition (N)) |
| and then Serious_Errors_Detected = 0 |
| then |
| if Is_True (Expr_Value (Condition (N))) then |
| Remove_Warning_Messages (Else_Statements (N)); |
| |
| if Present (Elsif_Parts (N)) then |
| E := First (Elsif_Parts (N)); |
| while Present (E) loop |
| Remove_Warning_Messages (Then_Statements (E)); |
| Next (E); |
| end loop; |
| end if; |
| |
| else |
| Remove_Warning_Messages (Then_Statements (N)); |
| end if; |
| end if; |
| |
| -- Warn on redundant if statement that has no effect |
| |
| -- Note, we could also check empty ELSIF parts ??? |
| |
| if Warn_On_Redundant_Constructs |
| |
| -- If statement must be from source |
| |
| and then Comes_From_Source (N) |
| |
| -- Condition must not have obvious side effect |
| |
| and then Has_No_Obvious_Side_Effects (Condition (N)) |
| |
| -- No elsif parts of else part |
| |
| and then No (Elsif_Parts (N)) |
| and then No (Else_Statements (N)) |
| |
| -- Then must be a single null statement |
| |
| and then List_Length (Then_Statements (N)) = 1 |
| then |
| -- Go to original node, since we may have rewritten something as |
| -- a null statement (e.g. a case we could figure the outcome of). |
| |
| declare |
| T : constant Node_Id := First (Then_Statements (N)); |
| S : constant Node_Id := Original_Node (T); |
| |
| begin |
| if Comes_From_Source (S) and then Nkind (S) = N_Null_Statement then |
| Error_Msg_N ("if statement has no effect?r?", N); |
| end if; |
| end; |
| end if; |
| end Analyze_If_Statement; |
| |
| ---------------------------------------- |
| -- Analyze_Implicit_Label_Declaration -- |
| ---------------------------------------- |
| |
| -- An implicit label declaration is generated in the innermost enclosing |
| -- declarative part. This is done for labels, and block and loop names. |
| |
| -- Note: any changes in this routine may need to be reflected in |
| -- Analyze_Label_Entity. |
| |
| procedure Analyze_Implicit_Label_Declaration (N : Node_Id) is |
| Id : constant Node_Id := Defining_Identifier (N); |
| begin |
| Enter_Name (Id); |
| Mutate_Ekind (Id, E_Label); |
| Set_Etype (Id, Standard_Void_Type); |
| Set_Enclosing_Scope (Id, Current_Scope); |
| end Analyze_Implicit_Label_Declaration; |
| |
| ------------------------------ |
| -- Analyze_Iteration_Scheme -- |
| ------------------------------ |
| |
| procedure Analyze_Iteration_Scheme (N : Node_Id) is |
| Cond : Node_Id; |
| Iter_Spec : Node_Id; |
| Loop_Spec : Node_Id; |
| |
| begin |
| -- For an infinite loop, there is no iteration scheme |
| |
| if No (N) then |
| return; |
| end if; |
| |
| Cond := Condition (N); |
| Iter_Spec := Iterator_Specification (N); |
| Loop_Spec := Loop_Parameter_Specification (N); |
| |
| if Present (Cond) then |
| Analyze_And_Resolve (Cond, Any_Boolean); |
| Check_Unset_Reference (Cond); |
| Set_Current_Value_Condition (N); |
| |
| elsif Present (Iter_Spec) then |
| Analyze_Iterator_Specification (Iter_Spec); |
| |
| else |
| Analyze_Loop_Parameter_Specification (Loop_Spec); |
| end if; |
| end Analyze_Iteration_Scheme; |
| |
| ------------------------------------ |
| -- Analyze_Iterator_Specification -- |
| ------------------------------------ |
| |
| procedure Analyze_Iterator_Specification (N : Node_Id) is |
| Def_Id : constant Node_Id := Defining_Identifier (N); |
| Iter_Name : constant Node_Id := Name (N); |
| Loc : constant Source_Ptr := Sloc (N); |
| Subt : constant Node_Id := Subtype_Indication (N); |
| |
| Bas : Entity_Id := Empty; -- initialize to prevent warning |
| Typ : Entity_Id; |
| |
| procedure Check_Reverse_Iteration (Typ : Entity_Id); |
| -- For an iteration over a container, if the loop carries the Reverse |
| -- indicator, verify that the container type has an Iterate aspect that |
| -- implements the reversible iterator interface. |
| |
| procedure Check_Subtype_Definition (Comp_Type : Entity_Id); |
| -- If a subtype indication is present, verify that it is consistent |
| -- with the component type of the array or container name. |
| -- In Ada 2022, the subtype indication may be an access definition, |
| -- if the array or container has elements of an anonymous access type. |
| |
| function Get_Cursor_Type (Typ : Entity_Id) return Entity_Id; |
| -- For containers with Iterator and related aspects, the cursor is |
| -- obtained by locating an entity with the proper name in the scope |
| -- of the type. |
| |
| ----------------------------- |
| -- Check_Reverse_Iteration -- |
| ----------------------------- |
| |
| procedure Check_Reverse_Iteration (Typ : Entity_Id) is |
| begin |
| if Reverse_Present (N) then |
| if Is_Array_Type (Typ) |
| or else Is_Reversible_Iterator (Typ) |
| or else |
| (Present (Find_Aspect (Typ, Aspect_Iterable)) |
| and then |
| Present |
| (Get_Iterable_Type_Primitive (Typ, Name_Previous))) |
| then |
| null; |
| else |
| Error_Msg_N |
| ("container type does not support reverse iteration", N); |
| end if; |
| end if; |
| end Check_Reverse_Iteration; |
| |
| ------------------------------- |
| -- Check_Subtype_Definition -- |
| ------------------------------- |
| |
| procedure Check_Subtype_Definition (Comp_Type : Entity_Id) is |
| begin |
| if not Present (Subt) then |
| return; |
| end if; |
| |
| if Is_Anonymous_Access_Type (Entity (Subt)) then |
| if not Is_Anonymous_Access_Type (Comp_Type) then |
| Error_Msg_NE |
| ("component type& is not an anonymous access", |
| Subt, Comp_Type); |
| |
| elsif not Conforming_Types |
| (Designated_Type (Entity (Subt)), |
| Designated_Type (Comp_Type), |
| Fully_Conformant) |
| then |
| Error_Msg_NE |
| ("subtype indication does not match component type&", |
| Subt, Comp_Type); |
| end if; |
| |
| elsif Present (Subt) |
| and then (not Covers (Base_Type (Bas), Comp_Type) |
| or else not Subtypes_Statically_Match (Bas, Comp_Type)) |
| then |
| if Is_Array_Type (Typ) then |
| Error_Msg_NE |
| ("subtype indication does not match component type&", |
| Subt, Comp_Type); |
| else |
| Error_Msg_NE |
| ("subtype indication does not match element type&", |
| Subt, Comp_Type); |
| end if; |
| end if; |
| end Check_Subtype_Definition; |
| |
| --------------------- |
| -- Get_Cursor_Type -- |
| --------------------- |
| |
| function Get_Cursor_Type (Typ : Entity_Id) return Entity_Id is |
| Ent : Entity_Id; |
| |
| begin |
| -- If iterator type is derived, the cursor is declared in the scope |
| -- of the parent type. |
| |
| if Is_Derived_Type (Typ) then |
| Ent := First_Entity (Scope (Etype (Typ))); |
| else |
| Ent := First_Entity (Scope (Typ)); |
| end if; |
| |
| while Present (Ent) loop |
| exit when Chars (Ent) = Name_Cursor; |
| Next_Entity (Ent); |
| end loop; |
| |
| if No (Ent) then |
| return Any_Type; |
| end if; |
| |
| -- The cursor is the target of generated assignments in the |
| -- loop, and cannot have a limited type. |
| |
| if Is_Limited_Type (Etype (Ent)) then |
| Error_Msg_N ("cursor type cannot be limited", N); |
| end if; |
| |
| return Etype (Ent); |
| end Get_Cursor_Type; |
| |
| -- Start of processing for Analyze_Iterator_Specification |
| |
| begin |
| Enter_Name (Def_Id); |
| |
| -- AI12-0151 specifies that when the subtype indication is present, it |
| -- must statically match the type of the array or container element. |
| -- To simplify this check, we introduce a subtype declaration with the |
| -- given subtype indication when it carries a constraint, and rewrite |
| -- the original as a reference to the created subtype entity. |
| |
| if Present (Subt) then |
| if Nkind (Subt) = N_Subtype_Indication then |
| declare |
| S : constant Entity_Id := Make_Temporary (Sloc (Subt), 'S'); |
| Decl : constant Node_Id := |
| Make_Subtype_Declaration (Loc, |
| Defining_Identifier => S, |
| Subtype_Indication => New_Copy_Tree (Subt)); |
| begin |
| Insert_Before (Parent (Parent (N)), Decl); |
| Analyze (Decl); |
| Rewrite (Subt, New_Occurrence_Of (S, Sloc (Subt))); |
| end; |
| |
| -- Ada 2022: the subtype definition may be for an anonymous |
| -- access type. |
| |
| elsif Nkind (Subt) = N_Access_Definition then |
| declare |
| S : constant Entity_Id := Make_Temporary (Sloc (Subt), 'S'); |
| Decl : Node_Id; |
| begin |
| if Present (Subtype_Mark (Subt)) then |
| Decl := |
| Make_Full_Type_Declaration (Loc, |
| Defining_Identifier => S, |
| Type_Definition => |
| Make_Access_To_Object_Definition (Loc, |
| All_Present => True, |
| Subtype_Indication => |
| New_Copy_Tree (Subtype_Mark (Subt)))); |
| |
| else |
| Decl := |
| Make_Full_Type_Declaration (Loc, |
| Defining_Identifier => S, |
| Type_Definition => |
| New_Copy_Tree |
| (Access_To_Subprogram_Definition (Subt))); |
| end if; |
| |
| Insert_Before (Parent (Parent (N)), Decl); |
| Analyze (Decl); |
| Freeze_Before (First (Statements (Parent (Parent (N)))), S); |
| Rewrite (Subt, New_Occurrence_Of (S, Sloc (Subt))); |
| end; |
| else |
| Analyze (Subt); |
| end if; |
| |
| -- Save entity of subtype indication for subsequent check |
| |
| Bas := Entity (Subt); |
| end if; |
| |
| Preanalyze_Range (Iter_Name); |
| |
| -- If the domain of iteration is a function call, make sure the function |
| -- itself is frozen. This is an issue if this is a local expression |
| -- function. |
| |
| if Nkind (Iter_Name) = N_Function_Call |
| and then Is_Entity_Name (Name (Iter_Name)) |
| and then Full_Analysis |
| and then (In_Assertion_Expr = 0 or else Assertions_Enabled) |
| then |
| Freeze_Before (N, Entity (Name (Iter_Name))); |
| end if; |
| |
| -- Set the kind of the loop variable, which is not visible within the |
| -- iterator name. |
| |
| Mutate_Ekind (Def_Id, E_Variable); |
| |
| -- Provide a link between the iterator variable and the container, for |
| -- subsequent use in cross-reference and modification information. |
| |
| if Of_Present (N) then |
| Set_Related_Expression (Def_Id, Iter_Name); |
| |
| -- For a container, the iterator is specified through the aspect |
| |
| if not Is_Array_Type (Etype (Iter_Name)) then |
| declare |
| Iterator : constant Entity_Id := |
| Find_Value_Of_Aspect |
| (Etype (Iter_Name), Aspect_Default_Iterator); |
| |
| I : Interp_Index; |
| It : Interp; |
| |
| begin |
| -- The domain of iteration must implement either the RM |
| -- iterator interface, or the SPARK Iterable aspect. |
| |
| if No (Iterator) then |
| if No (Find_Aspect (Etype (Iter_Name), Aspect_Iterable)) then |
| Error_Msg_NE |
| ("cannot iterate over&", |
| N, Base_Type (Etype (Iter_Name))); |
| return; |
| end if; |
| |
| elsif not Is_Overloaded (Iterator) then |
| Check_Reverse_Iteration (Etype (Iterator)); |
| |
| -- If Iterator is overloaded, use reversible iterator if one is |
| -- available. |
| |
| elsif Is_Overloaded (Iterator) then |
| Get_First_Interp (Iterator, I, It); |
| while Present (It.Nam) loop |
| if Ekind (It.Nam) = E_Function |
| and then Is_Reversible_Iterator (Etype (It.Nam)) |
| then |
| Set_Etype (Iterator, It.Typ); |
| Set_Entity (Iterator, It.Nam); |
| exit; |
| end if; |
| |
| Get_Next_Interp (I, It); |
| end loop; |
| |
| Check_Reverse_Iteration (Etype (Iterator)); |
| end if; |
| end; |
| end if; |
| end if; |
| |
| -- If the domain of iteration is an expression, create a declaration for |
| -- it, so that finalization actions are introduced outside of the loop. |
| -- The declaration must be a renaming (both in GNAT and GNATprove |
| -- modes), because the body of the loop may assign to elements. |
| |
| if not Is_Entity_Name (Iter_Name) |
| |
| -- When the context is a quantified expression, the renaming |
| -- declaration is delayed until the expansion phase if we are |
| -- doing expansion. |
| |
| and then (Nkind (Parent (N)) /= N_Quantified_Expression |
| or else (Operating_Mode = Check_Semantics |
| and then not GNATprove_Mode)) |
| |
| -- Do not perform this expansion when expansion is disabled, where the |
| -- temporary may hide the transformation of a selected component into |
| -- a prefixed function call, and references need to see the original |
| -- expression. |
| |
| and then (Expander_Active or GNATprove_Mode) |
| then |
| declare |
| Id : constant Entity_Id := Make_Temporary (Loc, 'R', Iter_Name); |
| Decl : Node_Id; |
| Act_S : Node_Id; |
| |
| begin |
| |
| -- If the domain of iteration is an array component that depends |
| -- on a discriminant, create actual subtype for it. Preanalysis |
| -- does not generate the actual subtype of a selected component. |
| |
| if Nkind (Iter_Name) = N_Selected_Component |
| and then Is_Array_Type (Etype (Iter_Name)) |
| then |
| Act_S := |
| Build_Actual_Subtype_Of_Component |
| (Etype (Selector_Name (Iter_Name)), Iter_Name); |
| Insert_Action (N, Act_S); |
| |
| if Present (Act_S) then |
| Typ := Defining_Identifier (Act_S); |
| else |
| Typ := Etype (Iter_Name); |
| end if; |
| |
| else |
| Typ := Etype (Iter_Name); |
| |
| -- Verify that the expression produces an iterator |
| |
| if not Of_Present (N) and then not Is_Iterator (Typ) |
| and then not Is_Array_Type (Typ) |
| and then No (Find_Aspect (Typ, Aspect_Iterable)) |
| then |
| Error_Msg_N |
| ("expect object that implements iterator interface", |
| Iter_Name); |
| end if; |
| end if; |
| |
| -- Protect against malformed iterator |
| |
| if Typ = Any_Type then |
| Error_Msg_N ("invalid expression in loop iterator", Iter_Name); |
| return; |
| end if; |
| |
| if not Of_Present (N) then |
| Check_Reverse_Iteration (Typ); |
| end if; |
| |
| -- For an element iteration over a slice, we must complete |
| -- the resolution and expansion of the slice bounds. These |
| -- can be arbitrary expressions, and the preanalysis that |
| -- was performed in preparation for the iteration may have |
| -- generated an itype whose bounds must be fully expanded. |
| -- We set the parent node to provide a proper insertion |
| -- point for generated actions, if any. |
| |
| if Nkind (Iter_Name) = N_Slice |
| and then Nkind (Discrete_Range (Iter_Name)) = N_Range |
| and then not Analyzed (Discrete_Range (Iter_Name)) |
| then |
| declare |
| Indx : constant Node_Id := |
| Entity (First_Index (Etype (Iter_Name))); |
| begin |
| Set_Parent (Indx, Iter_Name); |
| Resolve (Scalar_Range (Indx), Etype (Indx)); |
| end; |
| end if; |
| |
| -- The name in the renaming declaration may be a function call. |
| -- Indicate that it does not come from source, to suppress |
| -- spurious warnings on renamings of parameterless functions, |
| -- a common enough idiom in user-defined iterators. |
| |
| Decl := |
| Make_Object_Renaming_Declaration (Loc, |
| Defining_Identifier => Id, |
| Subtype_Mark => New_Occurrence_Of (Typ, Loc), |
| Name => |
| New_Copy_Tree (Iter_Name, New_Sloc => Loc)); |
| |
| Insert_Actions (Parent (Parent (N)), New_List (Decl)); |
| Rewrite (Name (N), New_Occurrence_Of (Id, Loc)); |
| Analyze (Name (N)); |
| Set_Etype (Id, Typ); |
| Set_Etype (Name (N), Typ); |
| end; |
| |
| -- Container is an entity or an array with uncontrolled components, or |
| -- else it is a container iterator given by a function call, typically |
| -- called Iterate in the case of predefined containers, even though |
| -- Iterate is not a reserved name. What matters is that the return type |
| -- of the function is an iterator type. |
| |
| elsif Is_Entity_Name (Iter_Name) then |
| Analyze (Iter_Name); |
| |
| if Nkind (Iter_Name) = N_Function_Call then |
| declare |
| C : constant Node_Id := Name (Iter_Name); |
| I : Interp_Index; |
| It : Interp; |
| |
| begin |
| if not Is_Overloaded (Iter_Name) then |
| Resolve (Iter_Name, Etype (C)); |
| |
| else |
| Get_First_Interp (C, I, It); |
| while It.Typ /= Empty loop |
| if Reverse_Present (N) then |
| if Is_Reversible_Iterator (It.Typ) then |
| Resolve (Iter_Name, It.Typ); |
| exit; |
| end if; |
| |
| elsif Is_Iterator (It.Typ) then |
| Resolve (Iter_Name, It.Typ); |
| exit; |
| end if; |
| |
| Get_Next_Interp (I, It); |
| end loop; |
| end if; |
| end; |
| |
| -- Domain of iteration is not overloaded |
| |
| else |
| Resolve (Iter_Name); |
| end if; |
| |
| if not Of_Present (N) then |
| Check_Reverse_Iteration (Etype (Iter_Name)); |
| end if; |
| end if; |
| |
| -- Get base type of container, for proper retrieval of Cursor type |
| -- and primitive operations. |
| |
| Typ := Base_Type (Etype (Iter_Name)); |
| |
| if Is_Array_Type (Typ) then |
| if Of_Present (N) then |
| Set_Etype (Def_Id, Component_Type (Typ)); |
| |
| -- The loop variable is aliased if the array components are |
| -- aliased. Likewise for the independent aspect. |
| |
| Set_Is_Aliased (Def_Id, Has_Aliased_Components (Typ)); |
| Set_Is_Independent (Def_Id, Has_Independent_Components (Typ)); |
| |
| -- AI12-0047 stipulates that the domain (array or container) |
| -- cannot be a component that depends on a discriminant if the |
| -- enclosing object is mutable, to prevent a modification of the |
| -- domain of iteration in the course of an iteration. |
| |
| -- If the object is an expression it has been captured in a |
| -- temporary, so examine original node. |
| |
| if Nkind (Original_Node (Iter_Name)) = N_Selected_Component |
| and then Is_Dependent_Component_Of_Mutable_Object |
| (Original_Node (Iter_Name)) |
| then |
| Error_Msg_N |
| ("iterable name cannot be a discriminant-dependent " |
| & "component of a mutable object", N); |
| end if; |
| |
| Check_Subtype_Definition (Component_Type (Typ)); |
| |
| -- Here we have a missing Range attribute |
| |
| else |
| Error_Msg_N |
| ("missing Range attribute in iteration over an array", N); |
| |
| -- In Ada 2012 mode, this may be an attempt at an iterator |
| |
| if Ada_Version >= Ada_2012 then |
| Error_Msg_NE |
| ("\if& is meant to designate an element of the array, use OF", |
| N, Def_Id); |
| end if; |
| |
| -- Prevent cascaded errors |
| |
| Mutate_Ekind (Def_Id, E_Loop_Parameter); |
| Set_Etype (Def_Id, Etype (First_Index (Typ))); |
| end if; |
| |
| -- Check for type error in iterator |
| |
| elsif Typ = Any_Type then |
| return; |
| |
| -- Iteration over a container |
| |
| else |
| Mutate_Ekind (Def_Id, E_Loop_Parameter); |
| Error_Msg_Ada_2012_Feature ("container iterator", Sloc (N)); |
| |
| -- OF present |
| |
| if Of_Present (N) then |
| if Has_Aspect (Typ, Aspect_Iterable) then |
| declare |
| Elt : constant Entity_Id := |
| Get_Iterable_Type_Primitive (Typ, Name_Element); |
| begin |
| if No (Elt) then |
| Error_Msg_N |
| ("missing Element primitive for iteration", N); |
| else |
| Set_Etype (Def_Id, Etype (Elt)); |
| Check_Reverse_Iteration (Typ); |
| end if; |
| end; |
| |
| Check_Subtype_Definition (Etype (Def_Id)); |
| |
| -- For a predefined container, the type of the loop variable is |
| -- the Iterator_Element aspect of the container type. |
| |
| else |
| declare |
| Element : constant Entity_Id := |
| Find_Value_Of_Aspect |
| (Typ, Aspect_Iterator_Element); |
| Iterator : constant Entity_Id := |
| Find_Value_Of_Aspect |
| (Typ, Aspect_Default_Iterator); |
| Orig_Iter_Name : constant Node_Id := |
| Original_Node (Iter_Name); |
| Cursor_Type : Entity_Id; |
| |
| begin |
| if No (Element) then |
| Error_Msg_NE ("cannot iterate over&", N, Typ); |
| return; |
| |
| else |
| Set_Etype (Def_Id, Entity (Element)); |
| Cursor_Type := Get_Cursor_Type (Typ); |
| pragma Assert (Present (Cursor_Type)); |
| |
| Check_Subtype_Definition (Etype (Def_Id)); |
| |
| -- If the container has a variable indexing aspect, the |
| -- element is a variable and is modifiable in the loop. |
| |
| if Has_Aspect (Typ, Aspect_Variable_Indexing) then |
| Mutate_Ekind (Def_Id, E_Variable); |
| end if; |
| |
| -- If the container is a constant, iterating over it |
| -- requires a Constant_Indexing operation. |
| |
| if not Is_Variable (Iter_Name) |
| and then not Has_Aspect (Typ, Aspect_Constant_Indexing) |
| then |
| Error_Msg_N |
| ("iteration over constant container require " |
| & "constant_indexing aspect", N); |
| |
| -- The Iterate function may have an in_out parameter, |
| -- and a constant container is thus illegal. |
| |
| elsif Present (Iterator) |
| and then Ekind (Entity (Iterator)) = E_Function |
| and then Ekind (First_Formal (Entity (Iterator))) /= |
| E_In_Parameter |
| and then not Is_Variable (Iter_Name) |
| then |
| Error_Msg_N ("variable container expected", N); |
| end if; |
| |
| -- Detect a case where the iterator denotes a component |
| -- of a mutable object which depends on a discriminant. |
| -- Note that the iterator may denote a function call in |
| -- qualified form, in which case this check should not |
| -- be performed. |
| |
| if Nkind (Orig_Iter_Name) = N_Selected_Component |
| and then |
| Present (Entity (Selector_Name (Orig_Iter_Name))) |
| and then |
| Ekind (Entity (Selector_Name (Orig_Iter_Name))) in |
| E_Component | E_Discriminant |
| and then Is_Dependent_Component_Of_Mutable_Object |
| (Orig_Iter_Name) |
| then |
| Error_Msg_N |
| ("container cannot be a discriminant-dependent " |
| & "component of a mutable object", N); |
| end if; |
| end if; |
| end; |
| end if; |
| |
| -- IN iterator, domain is a range, or a call to Iterate function |
| |
| else |
| -- For an iteration of the form IN, the name must denote an |
| -- iterator, typically the result of a call to Iterate. Give a |
| -- useful error message when the name is a container by itself. |
| |
| -- The type may be a formal container type, which has to have |
| -- an Iterable aspect detailing the required primitives. |
| |
| if Is_Entity_Name (Original_Node (Name (N))) |
| and then not Is_Iterator (Typ) |
| then |
| if Has_Aspect (Typ, Aspect_Iterable) then |
| null; |
| |
| elsif not Has_Aspect (Typ, Aspect_Iterator_Element) then |
| Error_Msg_NE |
| ("cannot iterate over&", Name (N), Typ); |
| else |
| Error_Msg_N |
| ("name must be an iterator, not a container", Name (N)); |
| end if; |
| |
| if Has_Aspect (Typ, Aspect_Iterable) then |
| null; |
| else |
| Error_Msg_NE |
| ("\to iterate directly over the elements of a container, " |
| & "write `of &`", Name (N), Original_Node (Name (N))); |
| |
| -- No point in continuing analysis of iterator spec |
| |
| return; |
| end if; |
| end if; |
| |
| -- If the name is a call (typically prefixed) to some Iterate |
| -- function, it has been rewritten as an object declaration. |
| -- If that object is a selected component, verify that it is not |
| -- a component of an unconstrained mutable object. |
| |
| if Nkind (Iter_Name) = N_Identifier |
| or else (not Expander_Active and Comes_From_Source (Iter_Name)) |
| then |
| declare |
| Orig_Node : constant Node_Id := Original_Node (Iter_Name); |
| Iter_Kind : constant Node_Kind := Nkind (Orig_Node); |
| Obj : Node_Id; |
| |
| begin |
| if Iter_Kind = N_Selected_Component then |
| Obj := Prefix (Orig_Node); |
| |
| elsif Iter_Kind = N_Function_Call then |
| Obj := First_Actual (Orig_Node); |
| |
| -- If neither, the name comes from source |
| |
| else |
| Obj := Iter_Name; |
| end if; |
| |
| if Nkind (Obj) = N_Selected_Component |
| and then Is_Dependent_Component_Of_Mutable_Object (Obj) |
| then |
| Error_Msg_N |
| ("container cannot be a discriminant-dependent " |
| & "component of a mutable object", N); |
| end if; |
| end; |
| end if; |
| |
| -- The result type of Iterate function is the classwide type of |
| -- the interface parent. We need the specific Cursor type defined |
| -- in the container package. We obtain it by name for a predefined |
| -- container, or through the Iterable aspect for a formal one. |
| |
| if Has_Aspect (Typ, Aspect_Iterable) then |
| Set_Etype (Def_Id, |
| Get_Cursor_Type |
| (Parent (Find_Value_Of_Aspect (Typ, Aspect_Iterable)), |
| Typ)); |
| |
| else |
| Set_Etype (Def_Id, Get_Cursor_Type (Typ)); |
| Check_Reverse_Iteration (Etype (Iter_Name)); |
| end if; |
| |
| end if; |
| end if; |
| |
| if Present (Iterator_Filter (N)) then |
| -- Preanalyze the filter. Expansion will take place when enclosing |
| -- loop is expanded. |
| |
| Preanalyze_And_Resolve (Iterator_Filter (N), Standard_Boolean); |
| end if; |
| end Analyze_Iterator_Specification; |
| |
| ------------------- |
| -- Analyze_Label -- |
| ------------------- |
| |
| -- Note: the semantic work required for analyzing labels (setting them as |
| -- reachable) was done in a prepass through the statements in the block, |
| -- so that forward gotos would be properly handled. See Analyze_Statements |
| -- for further details. The only processing required here is to deal with |
| -- optimizations that depend on an assumption of sequential control flow, |
| -- since of course the occurrence of a label breaks this assumption. |
| |
| procedure Analyze_Label (N : Node_Id) is |
| pragma Warnings (Off, N); |
| begin |
| Kill_Current_Values; |
| end Analyze_Label; |
| |
| -------------------------- |
| -- Analyze_Label_Entity -- |
| -------------------------- |
| |
| procedure Analyze_Label_Entity (E : Entity_Id) is |
| begin |
| Mutate_Ekind (E, E_Label); |
| Set_Etype (E, Standard_Void_Type); |
| Set_Enclosing_Scope (E, Current_Scope); |
| Set_Reachable (E, True); |
| end Analyze_Label_Entity; |
| |
| ------------------------------------------ |
| -- Analyze_Loop_Parameter_Specification -- |
| ------------------------------------------ |
| |
| procedure Analyze_Loop_Parameter_Specification (N : Node_Id) is |
| Loop_Nod : constant Node_Id := Parent (Parent (N)); |
| |
| procedure Check_Controlled_Array_Attribute (DS : Node_Id); |
| -- If the bounds are given by a 'Range reference on a function call |
| -- that returns a controlled array, introduce an explicit declaration |
| -- to capture the bounds, so that the function result can be finalized |
| -- in timely fashion. |
| |
| procedure Check_Predicate_Use (T : Entity_Id); |
| -- Diagnose Attempt to iterate through non-static predicate. Note that |
| -- a type with inherited predicates may have both static and dynamic |
| -- forms. In this case it is not sufficient to check the static |
| -- predicate function only, look for a dynamic predicate aspect as well. |
| |
| procedure Process_Bounds (R : Node_Id); |
| -- If the iteration is given by a range, create temporaries and |
| -- assignment statements block to capture the bounds and perform |
| -- required finalization actions in case a bound includes a function |
| -- call that uses the temporary stack. We first preanalyze a copy of |
| -- the range in order to determine the expected type, and analyze and |
| -- resolve the original bounds. |
| |
| -------------------------------------- |
| -- Check_Controlled_Array_Attribute -- |
| -------------------------------------- |
| |
| procedure Check_Controlled_Array_Attribute (DS : Node_Id) is |
| begin |
| if Nkind (DS) = N_Attribute_Reference |
| and then Is_Entity_Name (Prefix (DS)) |
| and then Ekind (Entity (Prefix (DS))) = E_Function |
| and then Is_Array_Type (Etype (Entity (Prefix (DS)))) |
| and then |
| Is_Controlled (Component_Type (Etype (Entity (Prefix (DS))))) |
| and then Expander_Active |
| then |
| declare |
| Loc : constant Source_Ptr := Sloc (N); |
| Arr : constant Entity_Id := Etype (Entity (Prefix (DS))); |
| Indx : constant Entity_Id := |
| Base_Type (Etype (First_Index (Arr))); |
| Subt : constant Entity_Id := Make_Temporary (Loc, 'S'); |
| Decl : Node_Id; |
| |
| begin |
| Decl := |
| Make_Subtype_Declaration (Loc, |
| Defining_Identifier => Subt, |
| Subtype_Indication => |
| Make_Subtype_Indication (Loc, |
| Subtype_Mark => New_Occurrence_Of (Indx, Loc), |
| Constraint => |
| Make_Range_Constraint (Loc, Relocate_Node (DS)))); |
| Insert_Before (Loop_Nod, Decl); |
| Analyze (Decl); |
| |
| Rewrite (DS, |
| Make_Attribute_Reference (Loc, |
| Prefix => New_Occurrence_Of (Subt, Loc), |
| Attribute_Name => Attribute_Name (DS))); |
| |
| Analyze (DS); |
| end; |
| end if; |
| end Check_Controlled_Array_Attribute; |
| |
| ------------------------- |
| -- Check_Predicate_Use -- |
| ------------------------- |
| |
| procedure Check_Predicate_Use (T : Entity_Id) is |
| begin |
| -- A predicated subtype is illegal in loops and related constructs |
| -- if the predicate is not static, or if it is a non-static subtype |
| -- of a statically predicated subtype. |
| |
| if Is_Discrete_Type (T) |
| and then Has_Predicates (T) |
| and then (not Has_Static_Predicate (T) |
| or else not Is_Static_Subtype (T) |
| or else Has_Dynamic_Predicate_Aspect (T)) |
| then |
| -- Seems a confusing message for the case of a static predicate |
| -- with a non-static subtype??? |
| |
| Bad_Predicated_Subtype_Use |
| ("cannot use subtype& with non-static predicate for loop " |
| & "iteration", Discrete_Subtype_Definition (N), |
| T, Suggest_Static => True); |
| |
| elsif Inside_A_Generic |
| and then Is_Generic_Formal (T) |
| and then Is_Discrete_Type (T) |
| then |
| Set_No_Dynamic_Predicate_On_Actual (T); |
| end if; |
| end Check_Predicate_Use; |
| |
| -------------------- |
| -- Process_Bounds -- |
| -------------------- |
| |
| procedure Process_Bounds (R : Node_Id) is |
| Loc : constant Source_Ptr := Sloc (N); |
| |
| function One_Bound |
| (Original_Bound : Node_Id; |
| Analyzed_Bound : Node_Id; |
| Typ : Entity_Id) return Node_Id; |
| -- Capture value of bound and return captured value |
| |
| --------------- |
| -- One_Bound -- |
| --------------- |
| |
| function One_Bound |
| (Original_Bound : Node_Id; |
| Analyzed_Bound : Node_Id; |
| Typ : Entity_Id) return Node_Id |
| is |
| Assign : Node_Id; |
| Decl : Node_Id; |
| Id : Entity_Id; |
| |
| begin |
| -- If the bound is a constant or an object, no need for a separate |
| -- declaration. If the bound is the result of previous expansion |
| -- it is already analyzed and should not be modified. Note that |
| -- the Bound will be resolved later, if needed, as part of the |
| -- call to Make_Index (literal bounds may need to be resolved to |
| -- type Integer). |
| |
| if Analyzed (Original_Bound) then |
| return Original_Bound; |
| |
| elsif Nkind (Analyzed_Bound) in |
| N_Integer_Literal | N_Character_Literal |
| or else Is_Entity_Name (Analyzed_Bound) |
| then |
| Analyze_And_Resolve (Original_Bound, Typ); |
| return Original_Bound; |
| |
| elsif Inside_Class_Condition_Preanalysis then |
| Analyze_And_Resolve (Original_Bound, Typ); |
| return Original_Bound; |
| end if; |
| |
| -- Normally, the best approach is simply to generate a constant |
| -- declaration that captures the bound. However, there is a nasty |
| -- case where this is wrong. If the bound is complex, and has a |
| -- possible use of the secondary stack, we need to generate a |
| -- separate assignment statement to ensure the creation of a block |
| -- which will release the secondary stack. |
| |
| -- We prefer the constant declaration, since it leaves us with a |
| -- proper trace of the value, useful in optimizations that get rid |
| -- of junk range checks. |
| |
| if not Has_Sec_Stack_Call (Analyzed_Bound) then |
| Analyze_And_Resolve (Original_Bound, Typ); |
| |
| -- Ensure that the bound is valid. This check should not be |
| -- generated when the range belongs to a quantified expression |
| -- as the construct is still not expanded into its final form. |
| |
| if Nkind (Parent (R)) /= N_Loop_Parameter_Specification |
| or else Nkind (Parent (Parent (R))) /= N_Quantified_Expression |
| then |
| Ensure_Valid (Original_Bound); |
| end if; |
| |
| Force_Evaluation (Original_Bound); |
| return Original_Bound; |
| end if; |
| |
| Id := Make_Temporary (Loc, 'R', Original_Bound); |
| |
| -- Here we make a declaration with a separate assignment |
| -- statement, and insert before loop header. |
| |
| Decl := |
| Make_Object_Declaration (Loc, |
| Defining_Identifier => Id, |
| Object_Definition => New_Occurrence_Of (Typ, Loc)); |
| |
| Assign := |
| Make_Assignment_Statement (Loc, |
| Name => New_Occurrence_Of (Id, Loc), |
| Expression => Relocate_Node (Original_Bound)); |
| |
| Insert_Actions (Loop_Nod, New_List (Decl, Assign)); |
| |
| -- Now that this temporary variable is initialized we decorate it |
| -- as safe-to-reevaluate to inform to the backend that no further |
| -- asignment will be issued and hence it can be handled as side |
| -- effect free. Note that this decoration must be done when the |
| -- assignment has been analyzed because otherwise it will be |
| -- rejected (see Analyze_Assignment). |
| |
| Set_Is_Safe_To_Reevaluate (Id); |
| |
| Rewrite (Original_Bound, New_Occurrence_Of (Id, Loc)); |
| |
| if Nkind (Assign) = N_Assignment_Statement then |
| return Expression (Assign); |
| else |
| return Original_Bound; |
| end if; |
| end One_Bound; |
| |
| Hi : constant Node_Id := High_Bound (R); |
| Lo : constant Node_Id := Low_Bound (R); |
| R_Copy : constant Node_Id := New_Copy_Tree (R); |
| New_Hi : Node_Id; |
| New_Lo : Node_Id; |
| Typ : Entity_Id; |
| |
| -- Start of processing for Process_Bounds |
| |
| begin |
| Set_Parent (R_Copy, Parent (R)); |
| Preanalyze_Range (R_Copy); |
| Typ := Etype (R_Copy); |
| |
| -- If the type of the discrete range is Universal_Integer, then the |
| -- bound's type must be resolved to Integer, and any object used to |
| -- hold the bound must also have type Integer, unless the literal |
| -- bounds are constant-folded expressions with a user-defined type. |
| |
| if Typ = Universal_Integer then |
| if Nkind (Lo) = N_Integer_Literal |
| and then Present (Etype (Lo)) |
| and then Scope (Etype (Lo)) /= Standard_Standard |
| then |
| Typ := Etype (Lo); |
| |
| elsif Nkind (Hi) = N_Integer_Literal |
| and then Present (Etype (Hi)) |
| and then Scope (Etype (Hi)) /= Standard_Standard |
| then |
| Typ := Etype (Hi); |
| |
| else |
| Typ := Standard_Integer; |
| end if; |
| end if; |
| |
| Set_Etype (R, Typ); |
| |
| New_Lo := One_Bound (Lo, Low_Bound (R_Copy), Typ); |
| New_Hi := One_Bound (Hi, High_Bound (R_Copy), Typ); |
| |
| -- Propagate staticness to loop range itself, in case the |
| -- corresponding subtype is static. |
| |
| if New_Lo /= Lo and then Is_OK_Static_Expression (New_Lo) then |
| Rewrite (Low_Bound (R), New_Copy (New_Lo)); |
| end if; |
| |
| if New_Hi /= Hi and then Is_OK_Static_Expression (New_Hi) then |
| Rewrite (High_Bound (R), New_Copy (New_Hi)); |
| end if; |
| end Process_Bounds; |
| |
| -- Local variables |
| |
| DS : constant Node_Id := Discrete_Subtype_Definition (N); |
| Id : constant Entity_Id := Defining_Identifier (N); |
| |
| DS_Copy : Node_Id; |
| |
| -- Start of processing for Analyze_Loop_Parameter_Specification |
| |
| begin |
| Enter_Name (Id); |
| |
| -- We always consider the loop variable to be referenced, since the loop |
| -- may be used just for counting purposes. |
| |
| Generate_Reference (Id, N, ' '); |
| |
| -- Check for the case of loop variable hiding a local variable (used |
| -- later on to give a nice warning if the hidden variable is never |
| -- assigned). |
| |
| declare |
| H : constant Entity_Id := Homonym (Id); |
| begin |
| if Present (H) |
| and then Ekind (H) = E_Variable |
| and then Is_Discrete_Type (Etype (H)) |
| and then Enclosing_Dynamic_Scope (H) = Enclosing_Dynamic_Scope (Id) |
| then |
| Set_Hiding_Loop_Variable (H, Id); |
| end if; |
| end; |
| |
| -- Analyze the subtype definition and create temporaries for the bounds. |
| -- Do not evaluate the range when preanalyzing a quantified expression |
| -- because bounds expressed as function calls with side effects will be |
| -- incorrectly replicated. |
| |
| if Nkind (DS) = N_Range |
| and then Expander_Active |
| and then Nkind (Parent (N)) /= N_Quantified_Expression |
| then |
| Process_Bounds (DS); |
| |
| -- Either the expander not active or the range of iteration is a subtype |
| -- indication, an entity, or a function call that yields an aggregate or |
| -- a container. |
| |
| else |
| DS_Copy := New_Copy_Tree (DS); |
| Set_Parent (DS_Copy, Parent (DS)); |
| Preanalyze_Range (DS_Copy); |
| |
| -- Ada 2012: If the domain of iteration is: |
| |
| -- a) a function call, |
| -- b) an identifier that is not a type, |
| -- c) an attribute reference 'Old (within a postcondition), |
| -- d) an unchecked conversion or a qualified expression with |
| -- the proper iterator type. |
| |
| -- then it is an iteration over a container. It was classified as |
| -- a loop specification by the parser, and must be rewritten now |
| -- to activate container iteration. The last case will occur within |
| -- an expanded inlined call, where the expansion wraps an actual in |
| -- an unchecked conversion when needed. The expression of the |
| -- conversion is always an object. |
| |
| if Nkind (DS_Copy) = N_Function_Call |
| |
| or else (Is_Entity_Name (DS_Copy) |
| and then not Is_Type (Entity (DS_Copy))) |
| |
| or else (Nkind (DS_Copy) = N_Attribute_Reference |
| and then Attribute_Name (DS_Copy) in |
| Name_Loop_Entry | Name_Old) |
| |
| or else Has_Aspect (Etype (DS_Copy), Aspect_Iterable) |
| |
| or else Nkind (DS_Copy) = N_Unchecked_Type_Conversion |
| or else (Nkind (DS_Copy) = N_Qualified_Expression |
| and then Is_Iterator (Etype (DS_Copy))) |
| then |
| -- This is an iterator specification. Rewrite it as such and |
| -- analyze it to capture function calls that may require |
| -- finalization actions. |
| |
| declare |
| I_Spec : constant Node_Id := |
| Make_Iterator_Specification (Sloc (N), |
| Defining_Identifier => Relocate_Node (Id), |
| Name => DS_Copy, |
| Subtype_Indication => Empty, |
| Reverse_Present => Reverse_Present (N)); |
| Scheme : constant Node_Id := Parent (N); |
| |
| begin |
| Set_Iterator_Specification (Scheme, I_Spec); |
| Set_Loop_Parameter_Specification (Scheme, Empty); |
| Set_Iterator_Filter (I_Spec, |
| Relocate_Node (Iterator_Filter (N))); |
| |
| Analyze_Iterator_Specification (I_Spec); |
| |
| -- In a generic context, analyze the original domain of |
| -- iteration, for name capture. |
| |
| if not Expander_Active then |
| Analyze (DS); |
| end if; |
| |
| -- Set kind of loop parameter, which may be used in the |
| -- subsequent analysis of the condition in a quantified |
| -- expression. |
| |
| Mutate_Ekind (Id, E_Loop_Parameter); |
| return; |
| end; |
| |
| -- Domain of iteration is not a function call, and is side-effect |
| -- free. |
| |
| else |
| -- A quantified expression that appears in a pre/post condition |
| -- is preanalyzed several times. If the range is given by an |
| -- attribute reference it is rewritten as a range, and this is |
| -- done even with expansion disabled. If the type is already set |
| -- do not reanalyze, because a range with static bounds may be |
| -- typed Integer by default. |
| |
| if Nkind (Parent (N)) = N_Quantified_Expression |
| and then Present (Etype (DS)) |
| then |
| null; |
| else |
| Analyze (DS); |
| end if; |
| end if; |
| end if; |
| |
| if DS = Error then |
| return; |
| end if; |
| |
| -- Some additional checks if we are iterating through a type |
| |
| if Is_Entity_Name (DS) |
| and then Present (Entity (DS)) |
| and then Is_Type (Entity (DS)) |
| then |
| -- The subtype indication may denote the completion of an incomplete |
| -- type declaration. |
| |
| if Ekind (Entity (DS)) = E_Incomplete_Type then |
| Set_Entity (DS, Get_Full_View (Entity (DS))); |
| Set_Etype (DS, Entity (DS)); |
| end if; |
| |
| Check_Predicate_Use (Entity (DS)); |
| end if; |
| |
| -- Error if not discrete type |
| |
| if not Is_Discrete_Type (Etype (DS)) then |
| Wrong_Type (DS, Any_Discrete); |
| Set_Etype (DS, Any_Type); |
| end if; |
| |
| Check_Controlled_Array_Attribute (DS); |
| |
| if Nkind (DS) = N_Subtype_Indication then |
| Check_Predicate_Use (Entity (Subtype_Mark (DS))); |
| end if; |
| |
| if Nkind (DS) not in N_Raise_xxx_Error then |
| Make_Index (DS, N); |
| end if; |
| |
| Mutate_Ekind (Id, E_Loop_Parameter); |
| |
| -- A quantified expression which appears in a pre- or post-condition may |
| -- be analyzed multiple times. The analysis of the range creates several |
| -- itypes which reside in different scopes depending on whether the pre- |
| -- or post-condition has been expanded. Update the type of the loop |
| -- variable to reflect the proper itype at each stage of analysis. |
| |
| -- Loop_Nod might not be present when we are preanalyzing a class-wide |
| -- pre/postcondition since preanalysis occurs in a place unrelated to |
| -- the actual code and the quantified expression may be the outermost |
| -- expression of the class-wide condition. |
| |
| if No (Etype (Id)) |
| or else Etype (Id) = Any_Type |
| or else |
| (Present (Etype (Id)) |
| and then Is_Itype (Etype (Id)) |
| and then Present (Loop_Nod) |
| and then Nkind (Parent (Loop_Nod)) = N_Expression_With_Actions |
| and then Nkind (Original_Node (Parent (Loop_Nod))) = |
| N_Quantified_Expression) |
| then |
| Set_Etype (Id, Etype (DS)); |
| end if; |
| |
| -- Treat a range as an implicit reference to the type, to inhibit |
| -- spurious warnings. |
| |
| Generate_Reference (Base_Type (Etype (DS)), N, ' '); |
| Set_Is_Known_Valid (Id, True); |
| |
| -- The loop is not a declarative part, so the loop variable must be |
| -- frozen explicitly. Do not freeze while preanalyzing a quantified |
| -- expression because the freeze node will not be inserted into the |
| -- tree due to flag Is_Spec_Expression being set. |
| |
| if Nkind (Parent (N)) /= N_Quantified_Expression then |
| declare |
| Flist : constant List_Id := Freeze_Entity (Id, N); |
| begin |
| if Is_Non_Empty_List (Flist) then |
| Insert_Actions (N, Flist); |
| end if; |
| end; |
| end if; |
| |
| -- Case where we have a range or a subtype, get type bounds |
| |
| if Nkind (DS) in N_Range | N_Subtype_Indication |
| and then not Error_Posted (DS) |
| and then Etype (DS) /= Any_Type |
| and then Is_Discrete_Type (Etype (DS)) |
| then |
| declare |
| L : Node_Id; |
| H : Node_Id; |
| Null_Range : Boolean := False; |
| |
| begin |
| if Nkind (DS) = N_Range then |
| L := Low_Bound (DS); |
| H := High_Bound (DS); |
| else |
| L := |
| Type_Low_Bound (Underlying_Type (Etype (Subtype_Mark (DS)))); |
| H := |
| Type_High_Bound (Underlying_Type (Etype (Subtype_Mark (DS)))); |
| end if; |
| |
| -- Check for null or possibly null range and issue warning. We |
| -- suppress such messages in generic templates and instances, |
| -- because in practice they tend to be dubious in these cases. The |
| -- check applies as well to rewritten array element loops where a |
| -- null range may be detected statically. |
| |
| if Compile_Time_Compare (L, H, Assume_Valid => True) = GT then |
| if Compile_Time_Compare (L, H, Assume_Valid => False) = GT then |
| -- Since we know the range of the loop is always null, |
| -- set the appropriate flag to remove the loop entirely |
| -- during expansion. |
| |
| Set_Is_Null_Loop (Loop_Nod); |
| Null_Range := True; |
| end if; |
| |
| -- Suppress the warning if inside a generic template or |
| -- instance, since in practice they tend to be dubious in these |
| -- cases since they can result from intended parameterization. |
| |
| if not Inside_A_Generic and then not In_Instance then |
| |
| -- Specialize msg if invalid values could make the loop |
| -- non-null after all. |
| |
| if Null_Range then |
| if Comes_From_Source (N) then |
| Error_Msg_N |
| ("??loop range is null, loop will not execute", DS); |
| end if; |
| |
| -- Here is where the loop could execute because of |
| -- invalid values, so issue appropriate message. |
| |
| elsif Comes_From_Source (N) then |
| Error_Msg_N |
| ("??loop range may be null, loop may not execute", |
| DS); |
| Error_Msg_N |
| ("??can only execute if invalid values are present", |
| DS); |
| end if; |
| end if; |
| |
| -- In either case, suppress warnings in the body of the loop, |
| -- since it is likely that these warnings will be inappropriate |
| -- if the loop never actually executes, which is likely. |
| |
| Set_Suppress_Loop_Warnings (Loop_Nod); |
| |
| -- The other case for a warning is a reverse loop where the |
| -- upper bound is the integer literal zero or one, and the |
| -- lower bound may exceed this value. |
| |
| -- For example, we have |
| |
| -- for J in reverse N .. 1 loop |
| |
| -- In practice, this is very likely to be a case of reversing |
| -- the bounds incorrectly in the range. |
| |
| elsif Reverse_Present (N) |
| and then Nkind (Original_Node (H)) = N_Integer_Literal |
| and then |
| (Intval (Original_Node (H)) = Uint_0 |
| or else |
| Intval (Original_Node (H)) = Uint_1) |
| then |
| -- Lower bound may in fact be known and known not to exceed |
| -- upper bound (e.g. reverse 0 .. 1) and that's OK. |
| |
| if Compile_Time_Known_Value (L) |
| and then Expr_Value (L) <= Expr_Value (H) |
| then |
| null; |
| |
| -- Otherwise warning is warranted |
| |
| else |
| Error_Msg_N ("??loop range may be null", DS); |
| Error_Msg_N ("\??bounds may be wrong way round", DS); |
| end if; |
| end if; |
| |
| -- Check if either bound is known to be outside the range of the |
| -- loop parameter type, this is e.g. the case of a loop from |
| -- 20..X where the type is 1..19. |
| |
| -- Such a loop is dubious since either it raises CE or it executes |
| -- zero times, and that cannot be useful! |
| |
| if Etype (DS) /= Any_Type |
| and then not Error_Posted (DS) |
| and then Nkind (DS) = N_Subtype_Indication |
| and then Nkind (Constraint (DS)) = N_Range_Constraint |
| then |
| declare |
| LLo : constant Node_Id := |
| Low_Bound (Range_Expression (Constraint (DS))); |
| LHi : constant Node_Id := |
| High_Bound (Range_Expression (Constraint (DS))); |
| |
| Bad_Bound : Node_Id := Empty; |
| -- Suspicious loop bound |
| |
| begin |
| -- At this stage L, H are the bounds of the type, and LLo |
| -- Lhi are the low bound and high bound of the loop. |
| |
| if Compile_Time_Compare (LLo, L, Assume_Valid => True) = LT |
| or else |
| Compile_Time_Compare (LLo, H, Assume_Valid => True) = GT |
| then |
| Bad_Bound := LLo; |
| end if; |
| |
| if Compile_Time_Compare (LHi, L, Assume_Valid => True) = LT |
| or else |
| Compile_Time_Compare (LHi, H, Assume_Valid => True) = GT |
| then |
| Bad_Bound := LHi; |
| end if; |
| |
| if Present (Bad_Bound) then |
| Error_Msg_N |
| ("suspicious loop bound out of range of " |
| & "loop subtype??", Bad_Bound); |
| Error_Msg_N |
| ("\loop executes zero times or raises " |
| & "Constraint_Error??", Bad_Bound); |
| end if; |
| |
| if Compile_Time_Compare (LLo, LHi, Assume_Valid => False) |
| = GT |
| then |
| Error_Msg_N ("??constrained range is null", |
| Constraint (DS)); |
| |
| -- Additional constraints on modular types can be |
| -- confusing, add more information. |
| |
| if Ekind (Etype (DS)) = E_Modular_Integer_Subtype then |
| Error_Msg_Uint_1 := Intval (LLo); |
| Error_Msg_Uint_2 := Intval (LHi); |
| Error_Msg_NE ("\iterator has modular type &, " & |
| "so the loop has bounds ^ ..^", |
| Constraint (DS), |
| Subtype_Mark (DS)); |
| end if; |
| |
| Set_Is_Null_Loop (Loop_Nod); |
| Null_Range := True; |
| |
| -- Suppress other warnings about the body of the loop, as |
| -- it will never execute. |
| Set_Suppress_Loop_Warnings (Loop_Nod); |
| end if; |
| end; |
| end if; |
| |
| -- This declare block is about warnings, if we get an exception while |
| -- testing for warnings, we simply abandon the attempt silently. This |
| -- most likely occurs as the result of a previous error, but might |
| -- just be an obscure case we have missed. In either case, not giving |
| -- the warning is perfectly acceptable. |
| |
| exception |
| when others => |
| -- With debug flag K we will get an exception unless an error |
| -- has already occurred (useful for debugging). |
| |
| if Debug_Flag_K then |
| Check_Error_Detected; |
| end if; |
| end; |
| end if; |
| |
| if Present (Iterator_Filter (N)) then |
| Analyze_And_Resolve (Iterator_Filter (N), Standard_Boolean); |
| end if; |
| |
| -- A loop parameter cannot be effectively volatile (SPARK RM 7.1.3(4)). |
| -- This check is relevant only when SPARK_Mode is on as it is not a |
| -- standard Ada legality check. |
| |
| if SPARK_Mode = On and then Is_Effectively_Volatile (Id) then |
| Error_Msg_N ("loop parameter cannot be volatile", Id); |
| end if; |
| end Analyze_Loop_Parameter_Specification; |
| |
| ---------------------------- |
| -- Analyze_Loop_Statement -- |
| ---------------------------- |
| |
| procedure Analyze_Loop_Statement (N : Node_Id) is |
| |
| -- The following exception is raised by routine Prepare_Loop_Statement |
| -- to avoid further analysis of a transformed loop. |
| |
| procedure Prepare_Loop_Statement |
| (Iter : Node_Id; |
| Stop_Processing : out Boolean); |
| -- Determine whether loop statement N with iteration scheme Iter must be |
| -- transformed prior to analysis, and if so, perform it. |
| -- If Stop_Processing is set to True, should stop further processing. |
| |
| ---------------------------- |
| -- Prepare_Loop_Statement -- |
| ---------------------------- |
| |
| procedure Prepare_Loop_Statement |
| (Iter : Node_Id; |
| Stop_Processing : out Boolean) |
| is |
| function Has_Sec_Stack_Default_Iterator |
| (Cont_Typ : Entity_Id) return Boolean; |
| pragma Inline (Has_Sec_Stack_Default_Iterator); |
| -- Determine whether container type Cont_Typ has a default iterator |
| -- that requires secondary stack management. |
| |
| function Is_Sec_Stack_Iteration_Primitive |
| (Cont_Typ : Entity_Id; |
| Iter_Prim_Nam : Name_Id) return Boolean; |
| pragma Inline (Is_Sec_Stack_Iteration_Primitive); |
| -- Determine whether container type Cont_Typ has an iteration routine |
| -- described by its name Iter_Prim_Nam that requires secondary stack |
| -- management. |
| |
| function Is_Wrapped_In_Block (Stmt : Node_Id) return Boolean; |
| pragma Inline (Is_Wrapped_In_Block); |
| -- Determine whether arbitrary statement Stmt is the sole statement |
| -- wrapped within some block, excluding pragmas. |
| |
| procedure Prepare_Iterator_Loop |
| (Iter_Spec : Node_Id; |
| Stop_Processing : out Boolean); |
| pragma Inline (Prepare_Iterator_Loop); |
| -- Prepare an iterator loop with iteration specification Iter_Spec |
| -- for transformation if needed. |
| -- If Stop_Processing is set to True, should stop further processing. |
| |
| procedure Prepare_Param_Spec_Loop |
| (Param_Spec : Node_Id; |
| Stop_Processing : out Boolean); |
| pragma Inline (Prepare_Param_Spec_Loop); |
| -- Prepare a discrete loop with parameter specification Param_Spec |
| -- for transformation if needed. |
| -- If Stop_Processing is set to True, should stop further processing. |
| |
| procedure Wrap_Loop_Statement (Manage_Sec_Stack : Boolean); |
| pragma Inline (Wrap_Loop_Statement); |
| -- Wrap loop statement N within a block. Flag Manage_Sec_Stack must |
| -- be set when the block must mark and release the secondary stack. |
| -- Should stop further processing after calling this procedure. |
| |
| ------------------------------------ |
| -- Has_Sec_Stack_Default_Iterator -- |
| ------------------------------------ |
| |
| function Has_Sec_Stack_Default_Iterator |
| (Cont_Typ : Entity_Id) return Boolean |
| is |
| Def_Iter : constant Node_Id := |
| Find_Value_Of_Aspect |
| (Cont_Typ, Aspect_Default_Iterator); |
| begin |
| return |
| Present (Def_Iter) |
| and then Requires_Transient_Scope (Etype (Def_Iter)); |
| end Has_Sec_Stack_Default_Iterator; |
| |
| -------------------------------------- |
| -- Is_Sec_Stack_Iteration_Primitive -- |
| -------------------------------------- |
| |
| function Is_Sec_Stack_Iteration_Primitive |
| (Cont_Typ : Entity_Id; |
| Iter_Prim_Nam : Name_Id) return Boolean |
| is |
| Iter_Prim : constant Entity_Id := |
| Get_Iterable_Type_Primitive |
| (Cont_Typ, Iter_Prim_Nam); |
| begin |
| return |
| Present (Iter_Prim) |
| and then Requires_Transient_Scope (Etype (Iter_Prim)); |
| end Is_Sec_Stack_Iteration_Primitive; |
| |
| ------------------------- |
| -- Is_Wrapped_In_Block -- |
| ------------------------- |
| |
| function Is_Wrapped_In_Block (Stmt : Node_Id) return Boolean is |
| Blk_HSS : Node_Id; |
| Blk_Id : Entity_Id; |
| Blk_Stmt : Node_Id; |
| |
| begin |
| Blk_Id := Current_Scope; |
| |
| -- The current context is a block. Inspect the statements of the |
| -- block to determine whether it wraps Stmt. |
| |
| if Ekind (Blk_Id) = E_Block |
| and then Present (Block_Node (Blk_Id)) |
| then |
| Blk_HSS := |
| Handled_Statement_Sequence (Parent (Block_Node (Blk_Id))); |
| |
| -- Skip leading pragmas introduced for invariant and predicate |
| -- checks. |
| |
| Blk_Stmt := First (Statements (Blk_HSS)); |
| while Present (Blk_Stmt) |
| and then Nkind (Blk_Stmt) = N_Pragma |
| loop |
| Next (Blk_Stmt); |
| end loop; |
| |
| return Blk_Stmt = Stmt and then No (Next (Blk_Stmt)); |
| end if; |
| |
| return False; |
| end Is_Wrapped_In_Block; |
| |
| --------------------------- |
| -- Prepare_Iterator_Loop -- |
| --------------------------- |
| |
| procedure Prepare_Iterator_Loop |
| (Iter_Spec : Node_Id; |
| Stop_Processing : out Boolean) |
| is |
| Cont_Typ : Entity_Id; |
| Nam : Node_Id; |
| Nam_Copy : Node_Id; |
| |
| begin |
| Stop_Processing := False; |
| |
| -- The iterator specification has syntactic errors. Transform the |
| -- loop into an infinite loop in order to safely perform at least |
| -- some minor analysis. This check must come first. |
| |
| if Error_Posted (Iter_Spec) then |
| Set_Iteration_Scheme (N, Empty); |
| Analyze (N); |
| Stop_Processing := True; |
| |
| -- Nothing to do when the loop is already wrapped in a block |
| |
| elsif Is_Wrapped_In_Block (N) then |
| null; |
| |
| -- Otherwise the iterator loop traverses an array or a container |
| -- and appears in the form |
| -- |
| -- for Def_Id in [reverse] Iterator_Name loop |
| -- for Def_Id [: Subtyp_Indic] of [reverse] Iterable_Name loop |
| |
| else |
| -- Prepare a copy of the iterated name for preanalysis. The |
| -- copy is semi inserted into the tree by setting its Parent |
| -- pointer. |
| |
| Nam := Name (Iter_Spec); |
| Nam_Copy := New_Copy_Tree (Nam); |
| Set_Parent (Nam_Copy, Parent (Nam)); |
| |
| -- Determine what the loop is iterating on |
| |
| Preanalyze_Range (Nam_Copy); |
| Cont_Typ := Etype (Nam_Copy); |
| |
| -- The iterator loop is traversing an array. This case does not |
| -- require any transformation. |
| |
| if Is_Array_Type (Cont_Typ) then |
| null; |
| |
| -- Otherwise unconditionally wrap the loop statement within |
| -- a block. The expansion of iterator loops may relocate the |
| -- iterator outside the loop, thus "leaking" its entity into |
| -- the enclosing scope. Wrapping the loop statement allows |
| -- for multiple iterator loops using the same iterator name |
| -- to coexist within the same scope. |
| -- |
| -- The block must manage the secondary stack when the iterator |
| -- loop is traversing a container using either |
| -- |
| -- * A default iterator obtained on the secondary stack |
| -- |
| -- * Call to Iterate where the iterator is returned on the |
| -- secondary stack. |
| -- |
| -- * Combination of First, Next, and Has_Element where the |
| -- first two return a cursor on the secondary stack. |
| |
| else |
| Wrap_Loop_Statement |
| (Manage_Sec_Stack => |
| Has_Sec_Stack_Default_Iterator (Cont_Typ) |
| or else Has_Sec_Stack_Call (Nam_Copy) |
| or else Is_Sec_Stack_Iteration_Primitive |
| (Cont_Typ, Name_First) |
| or else Is_Sec_Stack_Iteration_Primitive |
| (Cont_Typ, Name_Next)); |
| Stop_Processing := True; |
| end if; |
| end if; |
| end Prepare_Iterator_Loop; |
| |
| ----------------------------- |
| -- Prepare_Param_Spec_Loop -- |
| ----------------------------- |
| |
| procedure Prepare_Param_Spec_Loop |
| (Param_Spec : Node_Id; |
| Stop_Processing : out Boolean) |
| is |
| High : Node_Id; |
| Low : Node_Id; |
| Rng : Node_Id; |
| Rng_Copy : Node_Id; |
| Rng_Typ : Entity_Id; |
| |
| begin |
| Stop_Processing := False; |
| Rng := Discrete_Subtype_Definition (Param_Spec); |
| |
| -- Nothing to do when the loop is already wrapped in a block |
| |
| if Is_Wrapped_In_Block (N) then |
| null; |
| |
| -- The parameter specification appears in the form |
| -- |
| -- for Def_Id in Subtype_Mark Constraint loop |
| |
| elsif Nkind (Rng) = N_Subtype_Indication |
| and then Nkind (Range_Expression (Constraint (Rng))) = N_Range |
| then |
| Rng := Range_Expression (Constraint (Rng)); |
| |
| -- Preanalyze the bounds of the range constraint, setting |
| -- parent fields to associate the copied bounds with the range, |
| -- allowing proper tree climbing during preanalysis. |
| |
| Low := New_Copy_Tree (Low_Bound (Rng)); |
| High := New_Copy_Tree (High_Bound (Rng)); |
| |
| Set_Parent (Low, Rng); |
| Set_Parent (High, Rng); |
| |
| Preanalyze (Low); |
| Preanalyze (High); |
| |
| -- The bounds contain at least one function call that returns |
| -- on the secondary stack. Note that the loop must be wrapped |
| -- only when such a call exists. |
| |
| if Has_Sec_Stack_Call (Low) or else Has_Sec_Stack_Call (High) |
| then |
| Wrap_Loop_Statement (Manage_Sec_Stack => True); |
| Stop_Processing := True; |
| end if; |
| |
| -- Otherwise the parameter specification appears in the form |
| -- |
| -- for Def_Id in Range loop |
| |
| else |
| -- Prepare a copy of the discrete range for preanalysis. The |
| -- copy is semi inserted into the tree by setting its Parent |
| -- pointer. |
| |
| Rng_Copy := New_Copy_Tree (Rng); |
| Set_Parent (Rng_Copy, Parent (Rng)); |
| |
| -- Determine what the loop is iterating on |
| |
| Preanalyze_Range (Rng_Copy); |
| Rng_Typ := Etype (Rng_Copy); |
| |
| -- Wrap the loop statement within a block in order to manage |
| -- the secondary stack when the discrete range is |
| -- |
| -- * Either a Forward_Iterator or a Reverse_Iterator |
| -- |
| -- * Function call whose return type requires finalization |
| -- actions. |
| |
| -- ??? it is unclear why using Has_Sec_Stack_Call directly on |
| -- the discrete range causes the freeze node of an itype to be |
| -- in the wrong scope in complex assertion expressions. |
| |
| if Is_Iterator (Rng_Typ) |
| or else (Nkind (Rng_Copy) = N_Function_Call |
| and then Needs_Finalization (Rng_Typ)) |
| then |
| Wrap_Loop_Statement (Manage_Sec_Stack => True); |
| Stop_Processing := True; |
| end if; |
| end if; |
| end Prepare_Param_Spec_Loop; |
| |
| ------------------------- |
| -- Wrap_Loop_Statement -- |
| ------------------------- |
| |
| procedure Wrap_Loop_Statement (Manage_Sec_Stack : Boolean) is |
| Loc : constant Source_Ptr := Sloc (N); |
| |
| Blk : Node_Id; |
| Blk_Id : Entity_Id; |
| |
| begin |
| Blk := |
| Make_Block_Statement (Loc, |
| Declarations => New_List, |
| Handled_Statement_Sequence => |
| Make_Handled_Sequence_Of_Statements (Loc, |
| Statements => New_List (Relocate_Node (N)))); |
| |
| Add_Block_Identifier (Blk, Blk_Id); |
| Set_Uses_Sec_Stack (Blk_Id, Manage_Sec_Stack); |
| |
| Rewrite (N, Blk); |
| Analyze (N); |
| end Wrap_Loop_Statement; |
| |
| -- Local variables |
| |
| Iter_Spec : constant Node_Id := Iterator_Specification (Iter); |
| Param_Spec : constant Node_Id := Loop_Parameter_Specification (Iter); |
| |
| -- Start of processing for Prepare_Loop_Statement |
| |
| begin |
| Stop_Processing := False; |
| |
| if Present (Iter_Spec) then |
| Prepare_Iterator_Loop (Iter_Spec, Stop_Processing); |
| |
| elsif Present (Param_Spec) then |
| Prepare_Param_Spec_Loop (Param_Spec, Stop_Processing); |
| end if; |
| end Prepare_Loop_Statement; |
| |
| -- Local declarations |
| |
| Id : constant Node_Id := Identifier (N); |
| Iter : constant Node_Id := Iteration_Scheme (N); |
| Loc : constant Source_Ptr := Sloc (N); |
| Ent : Entity_Id; |
| Stmt : Node_Id; |
| |
| -- Start of processing for Analyze_Loop_Statement |
| |
| begin |
| if Present (Id) then |
| |
| -- Make name visible, e.g. for use in exit statements. Loop labels |
| -- are always considered to be referenced. |
| |
| Analyze (Id); |
| Ent := Entity (Id); |
| |
| -- Guard against serious error (typically, a scope mismatch when |
| -- semantic analysis is requested) by creating loop entity to |
| -- continue analysis. |
| |
| if No (Ent) then |
| if Total_Errors_Detected /= 0 then |
| Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L'); |
| else |
| raise Program_Error; |
| end if; |
| |
| -- Verify that the loop name is hot hidden by an unrelated |
| -- declaration in an inner scope. |
| |
| elsif Ekind (Ent) /= E_Label and then Ekind (Ent) /= E_Loop then |
| Error_Msg_Sloc := Sloc (Ent); |
| Error_Msg_N ("implicit label declaration for & is hidden#", Id); |
| |
| if Present (Homonym (Ent)) |
| and then Ekind (Homonym (Ent)) = E_Label |
| then |
| Set_Entity (Id, Ent); |
| Mutate_Ekind (Ent, E_Loop); |
| end if; |
| |
| else |
| Generate_Reference (Ent, N, ' '); |
| Generate_Definition (Ent); |
| |
| -- If we found a label, mark its type. If not, ignore it, since it |
| -- means we have a conflicting declaration, which would already |
| -- have been diagnosed at declaration time. Set Label_Construct |
| -- of the implicit label declaration, which is not created by the |
| -- parser for generic units. |
| |
| if Ekind (Ent) = E_Label then |
| Reinit_Field_To_Zero (Ent, F_Enclosing_Scope); |
| Mutate_Ekind (Ent, E_Loop); |
| |
| if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then |
| Set_Label_Construct (Parent (Ent), N); |
| end if; |
| end if; |
| end if; |
| |
| -- Case of no identifier present. Create one and attach it to the |
| -- loop statement for use as a scope and as a reference for later |
| -- expansions. Indicate that the label does not come from source, |
| -- and attach it to the loop statement so it is part of the tree, |
| -- even without a full declaration. |
| |
| else |
| Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L'); |
| Set_Etype (Ent, Standard_Void_Type); |
| Set_Identifier (N, New_Occurrence_Of (Ent, Loc)); |
| Set_Parent (Ent, N); |
| Set_Has_Created_Identifier (N); |
| end if; |
| |
| -- Determine whether the loop statement must be transformed prior to |
| -- analysis, and if so, perform it. This early modification is needed |
| -- when: |
| -- |
| -- * The loop has an erroneous iteration scheme. In this case the |
| -- loop is converted into an infinite loop in order to perform |
| -- minor analysis. |
| -- |
| -- * The loop is an Ada 2012 iterator loop. In this case the loop is |
| -- wrapped within a block to provide a local scope for the iterator. |
| -- If the iterator specification requires the secondary stack in any |
| -- way, the block is marked in order to manage it. |
| -- |
| -- * The loop is using a parameter specification where the discrete |
| -- range requires the secondary stack. In this case the loop is |
| -- wrapped within a block in order to manage the secondary stack. |
| |
| if Present (Iter) then |
| declare |
| Stop_Processing : Boolean; |
| begin |
| Prepare_Loop_Statement (Iter, Stop_Processing); |
| |
| if Stop_Processing then |
| return; |
| end if; |
| end; |
| end if; |
| |
| -- Kill current values on entry to loop, since statements in the body of |
| -- the loop may have been executed before the loop is entered. Similarly |
| -- we kill values after the loop, since we do not know that the body of |
| -- the loop was executed. |
| |
| Kill_Current_Values; |
| Push_Scope (Ent); |
| Analyze_Iteration_Scheme (Iter); |
| |
| -- Check for following case which merits a warning if the type E of is |
| -- a multi-dimensional array (and no explicit subscript ranges present). |
| |
| -- for J in E'Range |
| -- for K in E'Range |
| |
| if Present (Iter) |
| and then Present (Loop_Parameter_Specification (Iter)) |
| then |
| declare |
| LPS : constant Node_Id := Loop_Parameter_Specification (Iter); |
| DSD : constant Node_Id := |
| Original_Node (Discrete_Subtype_Definition (LPS)); |
| begin |
| if Nkind (DSD) = N_Attribute_Reference |
| and then Attribute_Name (DSD) = Name_Range |
| and then No (Expressions (DSD)) |
| then |
| declare |
| Typ : constant Entity_Id := Etype (Prefix (DSD)); |
| begin |
| if Is_Array_Type (Typ) |
| and then Number_Dimensions (Typ) > 1 |
| and then Nkind (Parent (N)) = N_Loop_Statement |
| and then Present (Iteration_Scheme (Parent (N))) |
| then |
| declare |
| OIter : constant Node_Id := |
| Iteration_Scheme (Parent (N)); |
| OLPS : constant Node_Id := |
| Loop_Parameter_Specification (OIter); |
| ODSD : constant Node_Id := |
| Original_Node (Discrete_Subtype_Definition (OLPS)); |
| begin |
| if Nkind (ODSD) = N_Attribute_Reference |
| and then Attribute_Name (ODSD) = Name_Range |
| and then No (Expressions (ODSD)) |
| and then Etype (Prefix (ODSD)) = Typ |
| then |
| Error_Msg_Sloc := Sloc (ODSD); |
| Error_Msg_N |
| ("inner range same as outer range#??", DSD); |
| end if; |
| end; |
| end if; |
| end; |
| end if; |
| end; |
| end if; |
| |
| -- Analyze the statements of the body except in the case of an Ada 2012 |
| -- iterator with the expander active. In this case the expander will do |
| -- a rewrite of the loop into a while loop. We will then analyze the |
| -- loop body when we analyze this while loop. |
| |
| -- We need to do this delay because if the container is for indefinite |
| -- types the actual subtype of the components will only be determined |
| -- when the cursor declaration is analyzed. |
| |
| -- If the expander is not active then we want to analyze the loop body |
| -- now even in the Ada 2012 iterator case, since the rewriting will not |
| -- be done. Insert the loop variable in the current scope, if not done |
| -- when analysing the iteration scheme. Set its kind properly to detect |
| -- improper uses in the loop body. |
| |
| -- In GNATprove mode, we do one of the above depending on the kind of |
| -- loop. If it is an iterator over an array, then we do not analyze the |
| -- loop now. We will analyze it after it has been rewritten by the |
| -- special SPARK expansion which is activated in GNATprove mode. We need |
| -- to do this so that other expansions that should occur in GNATprove |
| -- mode take into account the specificities of the rewritten loop, in |
| -- particular the introduction of a renaming (which needs to be |
| -- expanded). |
| |
| -- In other cases in GNATprove mode then we want to analyze the loop |
| -- body now, since no rewriting will occur. Within a generic the |
| -- GNATprove mode is irrelevant, we must analyze the generic for |
| -- non-local name capture. |
| |
| if Present (Iter) |
| and then Present (Iterator_Specification (Iter)) |
| then |
| if GNATprove_Mode |
| and then Is_Iterator_Over_Array (Iterator_Specification (Iter)) |
| and then not Inside_A_Generic |
| then |
| null; |
| |
| elsif not Expander_Active then |
| declare |
| I_Spec : constant Node_Id := Iterator_Specification (Iter); |
| Id : constant Entity_Id := Defining_Identifier (I_Spec); |
| |
| begin |
| if Scope (Id) /= Current_Scope then |
| Enter_Name (Id); |
| end if; |
| |
| -- In an element iterator, the loop parameter is a variable if |
| -- the domain of iteration (container or array) is a variable. |
| |
| if not Of_Present (I_Spec) |
| or else not Is_Variable (Name (I_Spec)) |
| then |
| Mutate_Ekind (Id, E_Loop_Parameter); |
| end if; |
| end; |
| |
| Analyze_Statements (Statements (N)); |
| end if; |
| |
| else |
| -- Pre-Ada2012 for-loops and while loops |
| |
| Analyze_Statements (Statements (N)); |
| end if; |
| |
| -- If the loop has no side effects, mark it for removal. |
| |
| if Side_Effect_Free_Loop (N) then |
| Set_Is_Null_Loop (N); |
| end if; |
| |
| -- When the iteration scheme of a loop contains attribute 'Loop_Entry, |
| -- the loop is transformed into a conditional block. Retrieve the loop. |
| |
| Stmt := N; |
| |
| if Subject_To_Loop_Entry_Attributes (Stmt) then |
| Stmt := Find_Loop_In_Conditional_Block (Stmt); |
| end if; |
| |
| -- Finish up processing for the loop. We kill all current values, since |
| -- in general we don't know if the statements in the loop have been |
| -- executed. We could do a bit better than this with a loop that we |
| -- know will execute at least once, but it's not worth the trouble and |
| -- the front end is not in the business of flow tracing. |
| |
| Process_End_Label (Stmt, 'e', Ent); |
| End_Scope; |
| Kill_Current_Values; |
| |
| -- Check for infinite loop. Skip check for generated code, since it |
| -- justs waste time and makes debugging the routine called harder. |
| |
| -- Note that we have to wait till the body of the loop is fully analyzed |
| -- before making this call, since Check_Infinite_Loop_Warning relies on |
| -- being able to use semantic visibility information to find references. |
| |
| if Comes_From_Source (Stmt) then |
| Check_Infinite_Loop_Warning (Stmt); |
| end if; |
| |
| -- Code after loop is unreachable if the loop has no WHILE or FOR and |
| -- contains no EXIT statements within the body of the loop. |
| |
| if No (Iter) and then not Has_Exit (Ent) then |
| Check_Unreachable_Code (Stmt); |
| end if; |
| end Analyze_Loop_Statement; |
| |
| ---------------------------- |
| -- Analyze_Null_Statement -- |
| ---------------------------- |
| |
| -- Note: the semantics of the null statement is implemented by a single |
| -- null statement, too bad everything isn't as simple as this. |
| |
| procedure Analyze_Null_Statement (N : Node_Id) is |
| pragma Warnings (Off, N); |
| begin |
| null; |
| end Analyze_Null_Statement; |
| |
| ------------------------- |
| -- Analyze_Target_Name -- |
| ------------------------- |
| |
| procedure Analyze_Target_Name (N : Node_Id) is |
| procedure Report_Error; |
| -- Complain about illegal use of target_name and rewrite it into unknown |
| -- identifier. |
| |
| ------------------ |
| -- Report_Error -- |
| ------------------ |
| |
| procedure Report_Error is |
| begin |
| Error_Msg_N |
| ("must appear in the right-hand side of an assignment statement", |
| N); |
| Rewrite (N, New_Occurrence_Of (Any_Id, Sloc (N))); |
| end Report_Error; |
| |