New Language: Ada

From-SVN: r45956

1 files changed, 1165 insertions, 0 deletions

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+------------------------------------------------------------------------------
+--                                                                          --
+--                         GNAT COMPILER COMPONENTS                         --
+--                                                                          --
+--                              P A R . C H 6                               --
+--                                                                          --
+--                                 B o d y                                  --
+--                                                                          --
+--                            $Revision: 1.81 $
+--                                                                          --
+--          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
+--                                                                          --
+-- GNAT is free software;  you can  redistribute it  and/or modify it under --
+-- terms of the  GNU General Public License as published  by the Free Soft- --
+-- ware  Foundation;  either version 2,  or (at your option) any later ver- --
+-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
+-- for  more details.  You should have  received  a copy of the GNU General --
+-- Public License  distributed with GNAT;  see file COPYING.  If not, write --
+-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
+-- MA 02111-1307, USA.                                                      --
+--                                                                          --
+-- GNAT was originally developed  by the GNAT team at  New York University. --
+-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
+--                                                                          --
+------------------------------------------------------------------------------
+
+pragma Style_Checks (All_Checks);
+--  Turn off subprogram body ordering check. Subprograms are in order
+--  by RM section rather than alphabetical
+
+with Sinfo.CN; use Sinfo.CN;
+
+separate (Par)
+package body Ch6 is
+
+   --  Local subprograms, used only in this chapter
+
+   function P_Defining_Designator        return Node_Id;
+   function P_Defining_Operator_Symbol   return Node_Id;
+
+   procedure Check_Junk_Semicolon_Before_Return;
+   --  Check for common error of junk semicolon before RETURN keyword of
+   --  function specification. If present, skip over it with appropriate
+   --  error message, leaving Scan_Ptr pointing to the RETURN after. This
+   --  routine also deals with a possibly misspelled version of Return.
+
+   ----------------------------------------
+   -- Check_Junk_Semicolon_Before_Return --
+   ----------------------------------------
+
+   procedure Check_Junk_Semicolon_Before_Return is
+      Scan_State : Saved_Scan_State;
+
+   begin
+      if Token = Tok_Semicolon then
+         Save_Scan_State (Scan_State);
+         Scan; -- past the semicolon
+
+         if Token = Tok_Return then
+            Restore_Scan_State (Scan_State);
+            Error_Msg_SC ("Unexpected semicolon ignored");
+            Scan; -- rescan past junk semicolon
+
+         else
+            Restore_Scan_State (Scan_State);
+         end if;
+
+      elsif Bad_Spelling_Of (Tok_Return) then
+         null;
+      end if;
+   end Check_Junk_Semicolon_Before_Return;
+
+   -----------------------------------------------------
+   -- 6.1  Subprogram (Also 6.3, 8.5.4, 10.1.3, 12.3) --
+   -----------------------------------------------------
+
+   --  This routine scans out a subprogram declaration, subprogram body,
+   --  subprogram renaming declaration or subprogram generic instantiation.
+
+   --  SUBPROGRAM_DECLARATION ::= SUBPROGRAM_SPECIFICATION;
+
+   --  ABSTRACT_SUBPROGRAM_DECLARATION ::=
+   --    SUBPROGRAM_SPECIFICATION is abstract;
+
+   --  SUBPROGRAM_SPECIFICATION ::=
+   --      procedure DEFINING_PROGRAM_UNIT_NAME PARAMETER_PROFILE
+   --    | function DEFINING_DESIGNATOR PARAMETER_AND_RESULT_PROFILE
+
+   --  PARAMETER_PROFILE ::= [FORMAL_PART]
+
+   --  PARAMETER_AND_RESULT_PROFILE ::= [FORMAL_PART] return SUBTYPE_MARK
+
+   --  SUBPROGRAM_BODY ::=
+   --    SUBPROGRAM_SPECIFICATION is
+   --      DECLARATIVE_PART
+   --    begin
+   --      HANDLED_SEQUENCE_OF_STATEMENTS
+   --    end [DESIGNATOR];
+
+   --  SUBPROGRAM_RENAMING_DECLARATION ::=
+   --    SUBPROGRAM_SPECIFICATION renames callable_entity_NAME;
+
+   --  SUBPROGRAM_BODY_STUB ::=
+   --    SUBPROGRAM_SPECIFICATION is separate;
+
+   --  GENERIC_INSTANTIATION ::=
+   --    procedure DEFINING_PROGRAM_UNIT_NAME is
+   --      new generic_procedure_NAME [GENERIC_ACTUAL_PART];
+   --  | function DEFINING_DESIGNATOR is
+   --      new generic_function_NAME [GENERIC_ACTUAL_PART];
+
+   --  The value in Pf_Flags indicates which of these possible declarations
+   --  is acceptable to the caller:
+
+   --    Pf_Flags.Decl                 Set if declaration OK
+   --    Pf_Flags.Gins                 Set if generic instantiation OK
+   --    Pf_Flags.Pbod                 Set if proper body OK
+   --    Pf_Flags.Rnam                 Set if renaming declaration OK
+   --    Pf_Flags.Stub                 Set if body stub OK
+
+   --  If an inappropriate form is encountered, it is scanned out but an
+   --  error message indicating that it is appearing in an inappropriate
+   --  context is issued. The only possible values for Pf_Flags are those
+   --  defined as constants in the Par package.
+
+   --  The caller has checked that the initial token is FUNCTION or PROCEDURE
+
+   --  Error recovery: cannot raise Error_Resync
+
+   function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id is
+      Specification_Node : Node_Id;
+      Name_Node   : Node_Id;
+      Fpart_List  : List_Id;
+      Fpart_Sloc  : Source_Ptr;
+      Return_Node : Node_Id;
+      Inst_Node   : Node_Id;
+      Body_Node   : Node_Id;
+      Decl_Node   : Node_Id;
+      Rename_Node : Node_Id;
+      Absdec_Node : Node_Id;
+      Stub_Node   : Node_Id;
+      Fproc_Sloc  : Source_Ptr;
+      Func        : Boolean;
+      Scan_State  : Saved_Scan_State;
+
+   begin
+      --  Set up scope stack entry. Note that the Labl field will be set later
+
+      SIS_Entry_Active := False;
+      SIS_Missing_Semicolon_Message := No_Error_Msg;
+      Push_Scope_Stack;
+      Scope.Table (Scope.Last).Sloc := Token_Ptr;
+      Scope.Table (Scope.Last).Etyp := E_Name;
+      Scope.Table (Scope.Last).Ecol := Start_Column;
+      Scope.Table (Scope.Last).Lreq := False;
+
+      Func := (Token = Tok_Function);
+      Fproc_Sloc := Token_Ptr;
+      Scan; -- past FUNCTION or PROCEDURE
+      Ignore (Tok_Type);
+      Ignore (Tok_Body);
+
+      if Func then
+         Name_Node := P_Defining_Designator;
+
+         if Nkind (Name_Node) = N_Defining_Operator_Symbol
+           and then Scope.Last = 1
+         then
+            Error_Msg_SP ("operator symbol not allowed at library level");
+            Name_Node := New_Entity (N_Defining_Identifier, Sloc (Name_Node));
+
+            --  Set name from file name, we need some junk name, and that's
+            --  as good as anything. This is only approximate, since we do
+            --  not do anything with non-standard name translations.
+
+            Get_Name_String (File_Name (Current_Source_File));
+
+            for J in 1 .. Name_Len loop
+               if Name_Buffer (J) = '.' then
+                  Name_Len := J - 1;
+                  exit;
+               end if;
+            end loop;
+
+            Set_Chars (Name_Node, Name_Find);
+            Set_Error_Posted (Name_Node);
+         end if;
+
+      else
+         Name_Node := P_Defining_Program_Unit_Name;
+      end if;
+
+      Scope.Table (Scope.Last).Labl := Name_Node;
+
+      if Token = Tok_Colon then
+         Error_Msg_SC ("redundant colon ignored");
+         Scan; -- past colon
+      end if;
+
+      --  Deal with generic instantiation, the one case in which we do not
+      --  have a subprogram specification as part of whatever we are parsing
+
+      if Token = Tok_Is then
+         Save_Scan_State (Scan_State); -- at the IS
+         T_Is; -- checks for redundant IS's
+
+         if Token = Tok_New then
+            if not Pf_Flags.Gins then
+               Error_Msg_SC ("generic instantation not allowed here!");
+            end if;
+
+            Scan; -- past NEW
+
+            if Func then
+               Inst_Node := New_Node (N_Function_Instantiation, Fproc_Sloc);
+               Set_Name (Inst_Node, P_Function_Name);
+            else
+               Inst_Node := New_Node (N_Procedure_Instantiation, Fproc_Sloc);
+               Set_Name (Inst_Node, P_Qualified_Simple_Name);
+            end if;
+
+            Set_Defining_Unit_Name (Inst_Node, Name_Node);
+            Set_Generic_Associations (Inst_Node, P_Generic_Actual_Part_Opt);
+            TF_Semicolon;
+            Pop_Scope_Stack; -- Don't need scope stack entry in this case
+            return Inst_Node;
+
+         else
+            Restore_Scan_State (Scan_State); -- to the IS
+         end if;
+      end if;
+
+      --  If not a generic instantiation, then we definitely have a subprogram
+      --  specification (all possibilities at this stage include one here)
+
+      Fpart_Sloc := Token_Ptr;
+
+      Check_Misspelling_Of (Tok_Return);
+
+      --  Scan formal part. First a special error check. If we have an
+      --  identifier here, then we have a definite error. If this identifier
+      --  is on the same line as the designator, then we assume it is the
+      --  first formal after a missing left parenthesis
+
+      if Token = Tok_Identifier
+        and then not Token_Is_At_Start_Of_Line
+      then
+            T_Left_Paren; -- to generate message
+            Fpart_List := P_Formal_Part;
+
+      --  Otherwise scan out an optional formal part in the usual manner
+
+      else
+         Fpart_List := P_Parameter_Profile;
+      end if;
+
+      --  We treat what we have as a function specification if FUNCTION was
+      --  used, or if a RETURN is present. This gives better error recovery
+      --  since later RETURN statements will be valid in either case.
+
+      Check_Junk_Semicolon_Before_Return;
+      Return_Node := Error;
+
+      if Token = Tok_Return then
+         if not Func then
+            Error_Msg ("PROCEDURE should be FUNCTION", Fproc_Sloc);
+            Func := True;
+         end if;
+
+         Scan; -- past RETURN
+         Return_Node := P_Subtype_Mark;
+         No_Constraint;
+
+      else
+         if Func then
+            Ignore (Tok_Right_Paren);
+            TF_Return;
+         end if;
+      end if;
+
+      if Func then
+         Specification_Node :=
+           New_Node (N_Function_Specification, Fproc_Sloc);
+         Set_Subtype_Mark (Specification_Node, Return_Node);
+
+      else
+         Specification_Node :=
+           New_Node (N_Procedure_Specification, Fproc_Sloc);
+      end if;
+
+      Set_Defining_Unit_Name (Specification_Node, Name_Node);
+      Set_Parameter_Specifications (Specification_Node, Fpart_List);
+
+      --  Error check: barriers not allowed on protected functions/procedures
+
+      if Token = Tok_When then
+         if Func then
+            Error_Msg_SC ("barrier not allowed on function, only on entry");
+         else
+            Error_Msg_SC ("barrier not allowed on procedure, only on entry");
+         end if;
+
+         Scan; -- past WHEN
+         Discard_Junk_Node (P_Expression);
+      end if;
+
+      --  Deal with case of semicolon ending a subprogram declaration
+
+      if Token = Tok_Semicolon then
+         if not Pf_Flags.Decl then
+            T_Is;
+         end if;
+
+         Scan; -- past semicolon
+
+         --  If semicolon is immediately followed by IS, then ignore the
+         --  semicolon, and go process the body.
+
+         if Token = Tok_Is then
+            Error_Msg_SP ("unexpected semicolon ignored");
+            T_Is; -- ignroe redundant IS's
+            goto Subprogram_Body;
+
+         --  If BEGIN follows in an appropriate column, we immediately
+         --  commence the error action of assuming that the previous
+         --  subprogram declaration should have been a subprogram body,
+         --  i.e. that the terminating semicolon should have been IS.
+
+         elsif Token = Tok_Begin
+            and then Start_Column >= Scope.Table (Scope.Last).Ecol
+         then
+            Error_Msg_SP (""";"" should be IS!");
+            goto Subprogram_Body;
+
+         else
+            goto Subprogram_Declaration;
+         end if;
+
+      --  Case of not followed by semicolon
+
+      else
+         --  Subprogram renaming declaration case
+
+         Check_Misspelling_Of (Tok_Renames);
+
+         if Token = Tok_Renames then
+            if not Pf_Flags.Rnam then
+               Error_Msg_SC ("renaming declaration not allowed here!");
+            end if;
+
+            Rename_Node :=
+              New_Node (N_Subprogram_Renaming_Declaration, Token_Ptr);
+            Scan; -- past RENAMES
+            Set_Name (Rename_Node, P_Name);
+            Set_Specification (Rename_Node, Specification_Node);
+            TF_Semicolon;
+            Pop_Scope_Stack;
+            return Rename_Node;
+
+         --  Case of IS following subprogram specification
+
+         elsif Token = Tok_Is then
+            T_Is; -- ignore redundant Is's
+
+            if Token_Name = Name_Abstract then
+               Check_95_Keyword (Tok_Abstract, Tok_Semicolon);
+            end if;
+
+            --  Deal nicely with (now obsolete) use of <> in place of abstract
+
+            if Token = Tok_Box then
+               Error_Msg_SC ("ABSTRACT expected");
+               Token := Tok_Abstract;
+            end if;
+
+            --  Abstract subprogram declaration case
+
+            if Token = Tok_Abstract then
+               Absdec_Node :=
+                 New_Node (N_Abstract_Subprogram_Declaration, Token_Ptr);
+               Set_Specification (Absdec_Node, Specification_Node);
+               Pop_Scope_Stack; -- discard unneeded entry
+               Scan; -- past ABSTRACT
+               TF_Semicolon;
+               return Absdec_Node;
+
+            --  Check for IS NEW with Formal_Part present and handle nicely
+
+            elsif Token = Tok_New then
+               Error_Msg
+                 ("formal part not allowed in instantiation", Fpart_Sloc);
+               Scan; -- past NEW
+
+               if Func then
+                  Inst_Node := New_Node (N_Function_Instantiation, Fproc_Sloc);
+               else
+                  Inst_Node :=
+                    New_Node (N_Procedure_Instantiation, Fproc_Sloc);
+               end if;
+
+               Set_Defining_Unit_Name (Inst_Node, Name_Node);
+               Set_Name (Inst_Node, P_Name);
+               Set_Generic_Associations (Inst_Node, P_Generic_Actual_Part_Opt);
+               TF_Semicolon;
+               Pop_Scope_Stack; -- Don't need scope stack entry in this case
+               return Inst_Node;
+
+            else
+               goto Subprogram_Body;
+            end if;
+
+         --  Here we have a missing IS or missing semicolon, we always guess
+         --  a missing semicolon, since we are pretty good at fixing up a
+         --  semicolon which should really be an IS
+
+         else
+            Error_Msg_AP ("missing "";""");
+            SIS_Missing_Semicolon_Message := Get_Msg_Id;
+            goto Subprogram_Declaration;
+         end if;
+      end if;
+
+      --  Processing for subprogram body
+
+      <<Subprogram_Body>>
+         if not Pf_Flags.Pbod then
+            Error_Msg_SP ("subprogram body not allowed here!");
+         end if;
+
+         --  Subprogram body stub case
+
+         if Separate_Present then
+            if not Pf_Flags.Stub then
+               Error_Msg_SC ("body stub not allowed here!");
+            end if;
+
+            if Nkind (Name_Node) = N_Defining_Operator_Symbol then
+               Error_Msg
+                 ("operator symbol cannot be used as subunit name",
+                  Sloc (Name_Node));
+            end if;
+
+            Stub_Node :=
+              New_Node (N_Subprogram_Body_Stub, Sloc (Specification_Node));
+            Set_Specification (Stub_Node, Specification_Node);
+            Scan; -- past SEPARATE
+            Pop_Scope_Stack;
+            TF_Semicolon;
+            return Stub_Node;
+
+         --  Subprogram body case
+
+         else
+            --  Here is the test for a suspicious IS (i.e. one that looks
+            --  like it might more properly be a semicolon). See separate
+            --  section discussing use of IS instead of semicolon in
+            --  package Parse.
+
+            if (Token in Token_Class_Declk
+                  or else
+                Token = Tok_Identifier)
+              and then Start_Column <= Scope.Table (Scope.Last).Ecol
+              and then Scope.Last /= 1
+            then
+               Scope.Table (Scope.Last).Etyp := E_Suspicious_Is;
+               Scope.Table (Scope.Last).S_Is := Prev_Token_Ptr;
+            end if;
+
+            Body_Node :=
+              New_Node (N_Subprogram_Body, Sloc (Specification_Node));
+            Set_Specification (Body_Node, Specification_Node);
+            Parse_Decls_Begin_End (Body_Node);
+            return Body_Node;
+         end if;
+
+      --  Processing for subprogram declaration
+
+      <<Subprogram_Declaration>>
+         Decl_Node :=
+           New_Node (N_Subprogram_Declaration, Sloc (Specification_Node));
+         Set_Specification (Decl_Node, Specification_Node);
+
+         --  If this is a context in which a subprogram body is permitted,
+         --  set active SIS entry in case (see section titled "Handling
+         --  Semicolon Used in Place of IS" in body of Parser package)
+         --  Note that SIS_Missing_Semicolon_Message is already set properly.
+
+         if Pf_Flags.Pbod then
+            SIS_Labl := Scope.Table (Scope.Last).Labl;
+            SIS_Sloc := Scope.Table (Scope.Last).Sloc;
+            SIS_Ecol := Scope.Table (Scope.Last).Ecol;
+            SIS_Declaration_Node := Decl_Node;
+            SIS_Semicolon_Sloc := Prev_Token_Ptr;
+            SIS_Entry_Active := True;
+         end if;
+
+         Pop_Scope_Stack;
+         return Decl_Node;
+
+   end P_Subprogram;
+
+   ---------------------------------
+   -- 6.1  Subprogram Declaration --
+   ---------------------------------
+
+   --  Parsed by P_Subprogram (6.1)
+
+   ------------------------------------------
+   -- 6.1  Abstract Subprogram Declaration --
+   ------------------------------------------
+
+   --  Parsed by P_Subprogram (6.1)
+
+   -----------------------------------
+   -- 6.1  Subprogram Specification --
+   -----------------------------------
+
+   --  SUBPROGRAM_SPECIFICATION ::=
+   --      procedure DEFINING_PROGRAM_UNIT_NAME PARAMETER_PROFILE
+   --    | function DEFINING_DESIGNATOR PARAMETER_AND_RESULT_PROFILE
+
+   --  PARAMETER_PROFILE ::= [FORMAL_PART]
+
+   --  PARAMETER_AND_RESULT_PROFILE ::= [FORMAL_PART] return SUBTYPE_MARK
+
+   --  Subprogram specifications that appear in subprogram declarations
+   --  are parsed by P_Subprogram (6.1). This routine is used in other
+   --  contexts where subprogram specifications occur.
+
+   --  Note: this routine does not affect the scope stack in any way
+
+   --  Error recovery: can raise Error_Resync
+
+   function P_Subprogram_Specification return Node_Id is
+      Specification_Node : Node_Id;
+
+   begin
+      if Token = Tok_Function then
+         Specification_Node := New_Node (N_Function_Specification, Token_Ptr);
+         Scan; -- past FUNCTION
+         Ignore (Tok_Body);
+         Set_Defining_Unit_Name (Specification_Node, P_Defining_Designator);
+         Set_Parameter_Specifications
+           (Specification_Node, P_Parameter_Profile);
+         Check_Junk_Semicolon_Before_Return;
+         TF_Return;
+         Set_Subtype_Mark (Specification_Node, P_Subtype_Mark);
+         No_Constraint;
+         return Specification_Node;
+
+      elsif Token = Tok_Procedure then
+         Specification_Node := New_Node (N_Procedure_Specification, Token_Ptr);
+         Scan; -- past PROCEDURE
+         Ignore (Tok_Body);
+         Set_Defining_Unit_Name
+           (Specification_Node, P_Defining_Program_Unit_Name);
+         Set_Parameter_Specifications
+           (Specification_Node, P_Parameter_Profile);
+         return Specification_Node;
+
+      else
+         Error_Msg_SC ("subprogram specification expected");
+         raise Error_Resync;
+      end if;
+   end P_Subprogram_Specification;
+
+   ---------------------
+   -- 6.1  Designator --
+   ---------------------
+
+   --  DESIGNATOR ::=
+   --    [PARENT_UNIT_NAME .] IDENTIFIER | OPERATOR_SYMBOL
+
+   --  The caller has checked that the initial token is an identifier,
+   --  operator symbol, or string literal. Note that we don't bother to
+   --  do much error diagnosis in this routine, since it is only used for
+   --  the label on END lines, and the routines in package Par.Endh will
+   --  check that the label is appropriate.
+
+   --  Error recovery: cannot raise Error_Resync
+
+   function P_Designator return Node_Id is
+      Ident_Node  : Node_Id;
+      Name_Node   : Node_Id;
+      Prefix_Node : Node_Id;
+
+      function Real_Dot return Boolean;
+      --  Tests if a current token is an interesting period, i.e. is followed
+      --  by an identifier or operator symbol or string literal. If not, it is
+      --  probably just incorrect punctuation to be caught by our caller. Note
+      --  that the case of an operator symbol or string literal is also an
+      --  error, but that is an error that we catch here. If the result is
+      --  True, a real dot has been scanned and we are positioned past it,
+      --  if the result is False, the scan position is unchanged.
+
+      function Real_Dot return Boolean is
+         Scan_State  : Saved_Scan_State;
+
+      begin
+         if Token /= Tok_Dot then
+            return False;
+
+         else
+            Save_Scan_State (Scan_State);
+            Scan; -- past dot
+
+            if Token = Tok_Identifier
+              or else Token = Tok_Operator_Symbol
+              or else Token = Tok_String_Literal
+            then
+               return True;
+
+            else
+               Restore_Scan_State (Scan_State);
+               return False;
+            end if;
+         end if;
+      end Real_Dot;
+
+   --  Start of processing for P_Designator
+
+   begin
+      Ident_Node := Token_Node;
+      Scan; -- past initial token
+
+      if Prev_Token = Tok_Operator_Symbol
+        or else Prev_Token = Tok_String_Literal
+        or else not Real_Dot
+      then
+         return Ident_Node;
+
+      --  Child name case
+
+      else
+         Prefix_Node := Ident_Node;
+
+         --  Loop through child names, on entry to this loop, Prefix contains
+         --  the name scanned so far, and Ident_Node is the last identifier.
+
+         loop
+            Name_Node := New_Node (N_Selected_Component, Prev_Token_Ptr);
+            Set_Prefix (Name_Node, Prefix_Node);
+            Ident_Node := P_Identifier;
+            Set_Selector_Name (Name_Node, Ident_Node);
+            Prefix_Node := Name_Node;
+            exit when not Real_Dot;
+         end loop;
+
+         --  On exit from the loop, Ident_Node is the last identifier scanned,
+         --  i.e. the defining identifier, and Prefix_Node is a node for the
+         --  entire name, structured (incorrectly!) as a selected component.
+
+         Name_Node := Prefix (Prefix_Node);
+         Change_Node (Prefix_Node, N_Designator);
+         Set_Name (Prefix_Node, Name_Node);
+         Set_Identifier (Prefix_Node, Ident_Node);
+         return Prefix_Node;
+      end if;
+
+   exception
+      when Error_Resync =>
+         while Token = Tok_Dot or else Token = Tok_Identifier loop
+            Scan;
+         end loop;
+
+         return Error;
+   end P_Designator;
+
+   ------------------------------
+   -- 6.1  Defining Designator --
+   ------------------------------
+
+   --  DEFINING_DESIGNATOR ::=
+   --    DEFINING_PROGRAM_UNIT_NAME | DEFINING_OPERATOR_SYMBOL
+
+   --  Error recovery: cannot raise Error_Resync
+
+   function P_Defining_Designator return Node_Id is
+   begin
+      if Token = Tok_Operator_Symbol then
+         return P_Defining_Operator_Symbol;
+
+      elsif Token = Tok_String_Literal then
+         Error_Msg_SC ("invalid operator name");
+         Scan; -- past junk string
+         return Error;
+
+      else
+         return P_Defining_Program_Unit_Name;
+      end if;
+   end P_Defining_Designator;
+
+   -------------------------------------
+   -- 6.1  Defining Program Unit Name --
+   -------------------------------------
+
+   --  DEFINING_PROGRAM_UNIT_NAME ::=
+   --    [PARENT_UNIT_NAME .] DEFINING_IDENTIFIER
+
+   --  Note: PARENT_UNIT_NAME may be present only in 95 mode at the outer level
+
+   --  Error recovery: cannot raise Error_Resync
+
+   function P_Defining_Program_Unit_Name return Node_Id is
+      Ident_Node  : Node_Id;
+      Name_Node   : Node_Id;
+      Prefix_Node : Node_Id;
+
+   begin
+      --  Set identifier casing if not already set and scan initial identifier
+
+      if Token = Tok_Identifier
+        and then Identifier_Casing (Current_Source_File) = Unknown
+      then
+         Set_Identifier_Casing (Current_Source_File, Determine_Token_Casing);
+      end if;
+
+      Ident_Node := P_Identifier;
+      Merge_Identifier (Ident_Node, Tok_Return);
+
+      --  Normal case (not child library unit name)
+
+      if Token /= Tok_Dot then
+         Change_Identifier_To_Defining_Identifier (Ident_Node);
+         return Ident_Node;
+
+      --  Child library unit name case
+
+      else
+         if Scope.Last > 1 then
+            Error_Msg_SP ("child unit allowed only at library level");
+            raise Error_Resync;
+
+         elsif Ada_83 then
+            Error_Msg_SP ("(Ada 83) child unit not allowed!");
+
+         end if;
+
+         Prefix_Node := Ident_Node;
+
+         --  Loop through child names, on entry to this loop, Prefix contains
+         --  the name scanned so far, and Ident_Node is the last identifier.
+
+         loop
+            exit when Token /= Tok_Dot;
+            Name_Node := New_Node (N_Selected_Component, Token_Ptr);
+            Scan; -- past period
+            Set_Prefix (Name_Node, Prefix_Node);
+            Ident_Node := P_Identifier;
+            Set_Selector_Name (Name_Node, Ident_Node);
+            Prefix_Node := Name_Node;
+         end loop;
+
+         --  On exit from the loop, Ident_Node is the last identifier scanned,
+         --  i.e. the defining identifier, and Prefix_Node is a node for the
+         --  entire name, structured (incorrectly!) as a selected component.
+
+         Name_Node := Prefix (Prefix_Node);
+         Change_Node (Prefix_Node, N_Defining_Program_Unit_Name);
+         Set_Name (Prefix_Node, Name_Node);
+         Change_Identifier_To_Defining_Identifier (Ident_Node);
+         Set_Defining_Identifier (Prefix_Node, Ident_Node);
+
+         --  All set with unit name parsed
+
+         return Prefix_Node;
+      end if;
+
+   exception
+      when Error_Resync =>
+         while Token = Tok_Dot or else Token = Tok_Identifier loop
+            Scan;
+         end loop;
+
+         return Error;
+   end P_Defining_Program_Unit_Name;
+
+   --------------------------
+   -- 6.1  Operator Symbol --
+   --------------------------
+
+   --  OPERATOR_SYMBOL ::= STRING_LITERAL
+
+   --  Operator symbol is returned by the scanner as Tok_Operator_Symbol
+
+   -----------------------------------
+   -- 6.1  Defining Operator Symbol --
+   -----------------------------------
+
+   --  DEFINING_OPERATOR_SYMBOL ::= OPERATOR_SYMBOL
+
+   --  The caller has checked that the initial symbol is an operator symbol
+
+   function P_Defining_Operator_Symbol return Node_Id is
+      Op_Node : Node_Id;
+
+   begin
+      Op_Node := Token_Node;
+      Change_Operator_Symbol_To_Defining_Operator_Symbol (Op_Node);
+      Scan; -- past operator symbol
+      return Op_Node;
+   end P_Defining_Operator_Symbol;
+
+   ----------------------------
+   -- 6.1  Parameter_Profile --
+   ----------------------------
+
+   --  PARAMETER_PROFILE ::= [FORMAL_PART]
+
+   --  Empty is returned if no formal part is present
+
+   --  Error recovery: cannot raise Error_Resync
+
+   function P_Parameter_Profile return List_Id is
+   begin
+      if Token = Tok_Left_Paren then
+         Scan; -- part left paren
+         return P_Formal_Part;
+      else
+         return No_List;
+      end if;
+   end P_Parameter_Profile;
+
+   ---------------------------------------
+   -- 6.1  Parameter And Result Profile --
+   ---------------------------------------
+
+   --  Parsed by its parent construct, which uses P_Parameter_Profile to
+   --  parse the parameters, and P_Subtype_Mark to parse the return type.
+
+   ----------------------
+   -- 6.1  Formal part --
+   ----------------------
+
+   --  FORMAL_PART ::= (PARAMETER_SPECIFICATION {; PARAMETER_SPECIFICATION})
+
+   --  PARAMETER_SPECIFICATION ::=
+   --    DEFINING_IDENTIFIER_LIST : MODE SUBTYPE_MARK
+   --      [:= DEFAULT_EXPRESSION]
+   --  | DEFINING_IDENTIFIER_LIST : ACCESS_DEFINITION
+   --      [:= DEFAULT_EXPRESSION]
+
+   --  This scans the construct Formal_Part. The caller has already checked
+   --  that the initial token is a left parenthesis, and skipped past it, so
+   --  that on entry Token is the first token following the left parenthesis.
+
+   --  Error recovery: cannot raise Error_Resync
+
+   function P_Formal_Part return List_Id is
+      Specification_List : List_Id;
+      Specification_Node : Node_Id;
+      Scan_State         : Saved_Scan_State;
+      Num_Idents         : Nat;
+      Ident              : Nat;
+      Ident_Sloc         : Source_Ptr;
+
+      Idents : array (Int range 1 .. 4096) of Entity_Id;
+      --  This array holds the list of defining identifiers. The upper bound
+      --  of 4096 is intended to be essentially infinite, and we do not even
+      --  bother to check for it being exceeded.
+
+   begin
+      Specification_List := New_List;
+
+      Specification_Loop : loop
+         begin
+            if Token = Tok_Pragma then
+               P_Pragmas_Misplaced;
+            end if;
+
+            Ignore (Tok_Left_Paren);
+            Ident_Sloc := Token_Ptr;
+            Idents (1) := P_Defining_Identifier;
+            Num_Idents := 1;
+
+            Ident_Loop : loop
+               exit Ident_Loop when Token = Tok_Colon;
+
+               --  The only valid tokens are colon and comma, so if we have
+               --  neither do a bit of investigation to see which is the
+               --  better choice for insertion.
+
+               if Token /= Tok_Comma then
+
+                  --  Assume colon if IN or OUT keyword found
+
+                  exit Ident_Loop when Token = Tok_In or else Token = Tok_Out;
+
+                  --  Otherwise scan ahead
+
+                  Save_Scan_State (Scan_State);
+                  Look_Ahead : loop
+
+                     --  If we run into a semicolon, then assume that a
+                     --  colon was missing, e.g.  Parms (X Y; ...). Also
+                     --  assume missing colon on EOF (a real disaster!)
+                     --  and on a right paren, e.g. Parms (X Y), and also
+                     --  on an assignment symbol, e.g. Parms (X Y := ..)
+
+                     if Token = Tok_Semicolon
+                       or else Token = Tok_Right_Paren
+                       or else Token = Tok_EOF
+                       or else Token = Tok_Colon_Equal
+                     then
+                        Restore_Scan_State (Scan_State);
+                        exit Ident_Loop;
+
+                     --  If we run into a colon, assume that we had a missing
+                     --  comma, e.g. Parms (A B : ...). Also assume a missing
+                     --  comma if we hit another comma, e.g. Parms (A B, C ..)
+
+                     elsif Token = Tok_Colon
+                       or else Token = Tok_Comma
+                     then
+                        Restore_Scan_State (Scan_State);
+                        exit Look_Ahead;
+                     end if;
+
+                     Scan;
+                  end loop Look_Ahead;
+               end if;
+
+               --  Here if a comma is present, or to be assumed
+
+               T_Comma;
+               Num_Idents := Num_Idents + 1;
+               Idents (Num_Idents) := P_Defining_Identifier;
+            end loop Ident_Loop;
+
+            --  Fall through the loop on encountering a colon, or deciding
+            --  that there is a missing colon.
+
+            T_Colon;
+
+            --  If there are multiple identifiers, we repeatedly scan the
+            --  type and initialization expression information by resetting
+            --  the scan pointer (so that we get completely separate trees
+            --  for each occurrence).
+
+            if Num_Idents > 1 then
+               Save_Scan_State (Scan_State);
+            end if;
+
+            --  Loop through defining identifiers in list
+
+            Ident := 1;
+
+            Ident_List_Loop : loop
+               Specification_Node :=
+                 New_Node (N_Parameter_Specification, Ident_Sloc);
+               Set_Defining_Identifier (Specification_Node, Idents (Ident));
+
+               if Token = Tok_Access then
+                  if Ada_83 then
+                     Error_Msg_SC ("(Ada 83) access parameters not allowed");
+                  end if;
+
+                  Set_Parameter_Type
+                    (Specification_Node, P_Access_Definition);
+
+               else
+                  P_Mode (Specification_Node);
+
+                  if Token = Tok_Procedure
+                       or else
+                     Token = Tok_Function
+                  then
+                     Error_Msg_SC ("formal subprogram parameter not allowed");
+                     Scan;
+
+                     if Token = Tok_Left_Paren then
+                        Discard_Junk_List (P_Formal_Part);
+                     end if;
+
+                     if Token = Tok_Return then
+                        Scan;
+                        Discard_Junk_Node (P_Subtype_Mark);
+                     end if;
+
+                     Set_Parameter_Type (Specification_Node, Error);
+
+                  else
+                     Set_Parameter_Type (Specification_Node, P_Subtype_Mark);
+                     No_Constraint;
+                  end if;
+               end if;
+
+               Set_Expression (Specification_Node, Init_Expr_Opt (True));
+
+               if Ident > 1 then
+                  Set_Prev_Ids (Specification_Node, True);
+               end if;
+
+               if Ident < Num_Idents then
+                  Set_More_Ids (Specification_Node, True);
+               end if;
+
+               Append (Specification_Node, Specification_List);
+               exit Ident_List_Loop when Ident = Num_Idents;
+               Ident := Ident + 1;
+               Restore_Scan_State (Scan_State);
+            end loop Ident_List_Loop;
+
+         exception
+            when Error_Resync =>
+               Resync_Semicolon_List;
+         end;
+
+         if Token = Tok_Semicolon then
+            Scan; -- past semicolon
+
+            --  If we have RETURN or IS after the semicolon, then assume
+            --  that semicolon should have been a right parenthesis and exit
+
+            if Token = Tok_Is or else Token = Tok_Return then
+               Error_Msg_SP ("expected "")"" in place of "";""");
+               exit Specification_Loop;
+            end if;
+
+         elsif Token = Tok_Right_Paren then
+            Scan; -- past right paren
+            exit Specification_Loop;
+
+         --  Special check for common error of using comma instead of semicolon
+
+         elsif Token = Tok_Comma then
+            T_Semicolon;
+            Scan; -- past comma
+
+         --  Special check for omitted separator
+
+         elsif Token = Tok_Identifier then
+            T_Semicolon;
+
+         --  If nothing sensible, skip to next semicolon or right paren
+
+         else
+            T_Semicolon;
+            Resync_Semicolon_List;
+
+            if Token = Tok_Semicolon then
+               Scan; -- past semicolon
+            else
+               T_Right_Paren;
+               exit Specification_Loop;
+            end if;
+         end if;
+      end loop Specification_Loop;
+
+      return Specification_List;
+   end P_Formal_Part;
+
+   ----------------------------------
+   -- 6.1  Parameter Specification --
+   ----------------------------------
+
+   --  Parsed by P_Formal_Part (6.1)
+
+   ---------------
+   -- 6.1  Mode --
+   ---------------
+
+   --  MODE ::= [in] | in out | out
+
+   --  There is no explicit node in the tree for the Mode. Instead the
+   --  In_Present and Out_Present flags are set in the parent node to
+   --  record the presence of keywords specifying the mode.
+
+   --  Error_Recovery: cannot raise Error_Resync
+
+   procedure P_Mode (Node : Node_Id) is
+   begin
+      if Token = Tok_In then
+         Scan; -- past IN
+         Set_In_Present (Node, True);
+      end if;
+
+      if Token = Tok_Out then
+         Scan; -- past OUT
+         Set_Out_Present (Node, True);
+      end if;
+
+      if Token = Tok_In then
+         Error_Msg_SC ("IN must preceed OUT in parameter mode");
+         Scan; -- past IN
+         Set_In_Present (Node, True);
+      end if;
+   end P_Mode;
+
+   --------------------------
+   -- 6.3  Subprogram Body --
+   --------------------------
+
+   --  Parsed by P_Subprogram (6.1)
+
+   -----------------------------------
+   -- 6.4  Procedure Call Statement --
+   -----------------------------------
+
+   --  Parsed by P_Sequence_Of_Statements (5.1)
+
+   ------------------------
+   -- 6.4  Function Call --
+   ------------------------
+
+   --  Parsed by P_Call_Or_Name (4.1)
+
+   --------------------------------
+   -- 6.4  Actual Parameter Part --
+   --------------------------------
+
+   --  Parsed by P_Call_Or_Name (4.1)
+
+   --------------------------------
+   -- 6.4  Parameter Association --
+   --------------------------------
+
+   --  Parsed by P_Call_Or_Name (4.1)
+
+   ------------------------------------
+   -- 6.4  Explicit Actual Parameter --
+   ------------------------------------
+
+   --  Parsed by P_Call_Or_Name (4.1)
+
+   ---------------------------
+   -- 6.5  Return Statement --
+   ---------------------------
+
+   --  RETURN_STATEMENT ::= return [EXPRESSION];
+
+   --  The caller has checked that the initial token is RETURN
+
+   --  Error recovery: can raise Error_Resync
+
+   function P_Return_Statement return Node_Id is
+      Return_Node : Node_Id;
+
+   begin
+      Return_Node := New_Node (N_Return_Statement, Token_Ptr);
+
+      --  Sloc points to RETURN
+      --  Expression (Op3)
+
+      Scan; -- past RETURN
+
+      if Token /= Tok_Semicolon then
+
+         --  If no semicolon, then scan an expression, except that
+         --  we avoid trying to scan an expression if we are at an
+         --  expression terminator since in that case the best error
+         --  message is probably that we have a missing semicolon.
+
+         if Token not in Token_Class_Eterm then
+            Set_Expression (Return_Node, P_Expression_No_Right_Paren);
+         end if;
+      end if;
+
+      TF_Semicolon;
+      return Return_Node;
+   end P_Return_Statement;
+
+end Ch6;