path: root/gcc/ada/par-prag.adb

------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                             P A R . P R A G                              --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 1992-2004 Free Software Foundation, Inc.          --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 2,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
-- for  more details.  You should have  received  a copy of the GNU General --
-- Public License  distributed with GNAT;  see file COPYING.  If not, write --
-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
-- MA 02111-1307, USA.                                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  Generally the parser checks the basic syntax of pragmas, but does not
--  do specialized syntax checks for individual pragmas, these are deferred
--  to semantic analysis time (see unit Sem_Prag). There are some pragmas
--  which require recognition and either partial or complete processing
--  during parsing, and this unit performs this required processing.

with Fname.UF; use Fname.UF;
with Osint;    use Osint;
with Stringt;  use Stringt;
with Stylesw;  use Stylesw;
with Uintp;    use Uintp;
with Uname;    use Uname;

separate (Par)

function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id is
   Pragma_Name : constant Name_Id    := Chars (Pragma_Node);
   Pragma_Sloc : constant Source_Ptr := Sloc (Pragma_Node);
   Arg_Count   : Nat;
   Arg_Node    : Node_Id;

   -----------------------
   -- Local Subprograms --
   -----------------------

   function Arg1 return Node_Id;
   function Arg2 return Node_Id;
   function Arg3 return Node_Id;
   --  Obtain specified Pragma_Argument_Association. It is allowable to call
   --  the routine for the argument one past the last present argument, but
   --  that is the only case in which a non-present argument can be referenced.

   procedure Check_Arg_Count (Required : Int);
   --  Check argument count for pragma = Required.
   --  If not give error and raise Error_Resync.

   procedure Check_Arg_Is_String_Literal (Arg : Node_Id);
   --  Check the expression of the specified argument to make sure that it
   --  is a string literal. If not give error and raise Error_Resync.

   procedure Check_Arg_Is_On_Or_Off (Arg : Node_Id);
   --  Check the expression of the specified argument to make sure that it
   --  is an identifier which is either ON or OFF, and if not, then issue
   --  an error message and raise Error_Resync.

   procedure Check_No_Identifier (Arg : Node_Id);
   --  Checks that the given argument does not have an identifier. If
   --  an identifier is present, then an error message is issued, and
   --  Error_Resync is raised.

   procedure Check_Optional_Identifier (Arg : Node_Id; Id : Name_Id);
   --  Checks if the given argument has an identifier, and if so, requires
   --  it to match the given identifier name. If there is a non-matching
   --  identifier, then an error message is given and Error_Resync raised.

   procedure Check_Required_Identifier (Arg : Node_Id; Id : Name_Id);
   --  Same as Check_Optional_Identifier, except that the name is required
   --  to be present and to match the given Id value.

   ----------
   -- Arg1 --
   ----------

   function Arg1 return Node_Id is
   begin
      return First (Pragma_Argument_Associations (Pragma_Node));
   end Arg1;

   ----------
   -- Arg2 --
   ----------

   function Arg2 return Node_Id is
   begin
      return Next (Arg1);
   end Arg2;

   ----------
   -- Arg3 --
   ----------

   function Arg3 return Node_Id is
   begin
      return Next (Arg2);
   end Arg3;

   ---------------------
   -- Check_Arg_Count --
   ---------------------

   procedure Check_Arg_Count (Required : Int) is
   begin
      if Arg_Count /= Required then
         Error_Msg ("wrong number of arguments for pragma%", Pragma_Sloc);
         raise Error_Resync;
      end if;
   end Check_Arg_Count;

   ----------------------------
   -- Check_Arg_Is_On_Or_Off --
   ----------------------------

   procedure Check_Arg_Is_On_Or_Off (Arg : Node_Id) is
      Argx : constant Node_Id := Expression (Arg);

   begin
      if Nkind (Expression (Arg)) /= N_Identifier
        or else (Chars (Argx) /= Name_On
                   and then
                 Chars (Argx) /= Name_Off)
      then
         Error_Msg_Name_2 := Name_On;
         Error_Msg_Name_3 := Name_Off;

         Error_Msg
           ("argument for pragma% must be% or%", Sloc (Argx));
         raise Error_Resync;
      end if;
   end Check_Arg_Is_On_Or_Off;

   ---------------------------------
   -- Check_Arg_Is_String_Literal --
   ---------------------------------

   procedure Check_Arg_Is_String_Literal (Arg : Node_Id) is
   begin
      if Nkind (Expression (Arg)) /= N_String_Literal then
         Error_Msg
           ("argument for pragma% must be string literal",
             Sloc (Expression (Arg)));
         raise Error_Resync;
      end if;
   end Check_Arg_Is_String_Literal;

   -------------------------
   -- Check_No_Identifier --
   -------------------------

   procedure Check_No_Identifier (Arg : Node_Id) is
   begin
      if Chars (Arg) /= No_Name then
         Error_Msg_N ("pragma% does not permit named arguments", Arg);
         raise Error_Resync;
      end if;
   end Check_No_Identifier;

   -------------------------------
   -- Check_Optional_Identifier --
   -------------------------------

   procedure Check_Optional_Identifier (Arg : Node_Id; Id : Name_Id) is
   begin
      if Present (Arg) and then Chars (Arg) /= No_Name then
         if Chars (Arg) /= Id then
            Error_Msg_Name_2 := Id;
            Error_Msg_N ("pragma% argument expects identifier%", Arg);
         end if;
      end if;
   end Check_Optional_Identifier;

   -------------------------------
   -- Check_Required_Identifier --
   -------------------------------

   procedure Check_Required_Identifier (Arg : Node_Id; Id : Name_Id) is
   begin
      if Chars (Arg) /= Id then
         Error_Msg_Name_2 := Id;
         Error_Msg_N ("pragma% argument must have identifier%", Arg);
      end if;
   end Check_Required_Identifier;

   ----------
   -- Prag --
   ----------

begin
   Error_Msg_Name_1 := Pragma_Name;

   --  Ignore unrecognized pragma. We let Sem post the warning for this, since
   --  it is a semantic error, not a syntactic one (we have already checked
   --  the syntax for the unrecognized pragma as required by (RM 2.8(11)).

   if not Is_Pragma_Name (Chars (Pragma_Node)) then
      return Pragma_Node;
   end if;

   --  Count number of arguments. This loop also checks if any of the arguments
   --  are Error, indicating a syntax error as they were parsed. If so, we
   --  simply return, because we get into trouble with cascaded errors if we
   --  try to perform our error checks on junk arguments.

   Arg_Count := 0;

   if Present (Pragma_Argument_Associations (Pragma_Node)) then
      Arg_Node := Arg1;

      while Arg_Node /= Empty loop
         Arg_Count := Arg_Count + 1;

         if Expression (Arg_Node) = Error then
            return Error;
         end if;

         Next (Arg_Node);
      end loop;
   end if;

   --  Remaining processing is pragma dependent

   case Get_Pragma_Id (Pragma_Name) is

      ------------
      -- Ada_83 --
      ------------

      --  This pragma must be processed at parse time, since we want to set
      --  the Ada version properly at parse time to recognize the appropriate
      --  Ada version syntax.

      when Pragma_Ada_83 =>
         Ada_Version := Ada_83;

      ------------
      -- Ada_95 --
      ------------

      --  This pragma must be processed at parse time, since we want to set
      --  the Ada version properly at parse time to recognize the appropriate
      --  Ada version syntax.

      when Pragma_Ada_95 =>
         Ada_Version := Ada_95;

      ------------
      -- Ada_05 --
      ------------

      --  This pragma must be processed at parse time, since we want to set
      --  the Ada version properly at parse time to recognize the appropriate
      --  Ada version syntax.

      when Pragma_Ada_05 =>
         Ada_Version := Ada_05;

      -----------
      -- Debug --
      -----------

      --  pragma Debug (PROCEDURE_CALL_STATEMENT);

      --  This has to be processed by the parser because of the very peculiar
      --  form of the second parameter, which is syntactically from a formal
      --  point of view a function call (since it must be an expression), but
      --  semantically we treat it as a procedure call (which has exactly the
      --  same syntactic form, so that's why we can get away with this!)

      when Pragma_Debug =>
         Check_Arg_Count (1);
         Check_No_Identifier (Arg1);

         declare
            Expr : constant Node_Id := New_Copy (Expression (Arg1));

         begin
            if Nkind (Expr) /= N_Indexed_Component
              and then Nkind (Expr) /= N_Function_Call
              and then Nkind (Expr) /= N_Identifier
              and then Nkind (Expr) /= N_Selected_Component
            then
               Error_Msg
                 ("argument of pragma% is not procedure call", Sloc (Expr));
               raise Error_Resync;
            else
               Set_Debug_Statement
                 (Pragma_Node, P_Statement_Name (Expr));
            end if;
         end;

      -------------------------------
      -- Extensions_Allowed (GNAT) --
      -------------------------------

      --  pragma Extensions_Allowed (Off | On)

      --  The processing for pragma Extensions_Allowed must be done at
      --  parse time, since extensions mode may affect what is accepted.

      when Pragma_Extensions_Allowed =>
         Check_Arg_Count (1);
         Check_No_Identifier (Arg1);
         Check_Arg_Is_On_Or_Off (Arg1);

         if Chars (Expression (Arg1)) = Name_On then
            Extensions_Allowed := True;
            Ada_Version := Ada_Version_Type'Last;
         else
            Extensions_Allowed := False;
            Ada_Version := Ada_Version_Type'Min (Ada_Version, Ada_95);
         end if;

      ----------------
      -- List (2.8) --
      ----------------

      --  pragma List (Off | On)

      --  The processing for pragma List must be done at parse time,
      --  since a listing can be generated in parse only mode.

      when Pragma_List =>
         Check_Arg_Count (1);
         Check_No_Identifier (Arg1);
         Check_Arg_Is_On_Or_Off (Arg1);

         --  We unconditionally make a List_On entry for the pragma, so that
         --  in the List (Off) case, the pragma will print even in a region
         --  of code with listing turned off (this is required!)

         List_Pragmas.Increment_Last;
         List_Pragmas.Table (List_Pragmas.Last) :=
           (Ptyp => List_On, Ploc => Sloc (Pragma_Node));

         --  Now generate the list off entry for pragma List (Off)

         if Chars (Expression (Arg1)) = Name_Off then
            List_Pragmas.Increment_Last;
            List_Pragmas.Table (List_Pragmas.Last) :=
              (Ptyp => List_Off, Ploc => Semi);
         end if;

      ----------------
      -- Page (2.8) --
      ----------------

      --  pragma Page;

      --  Processing for this pragma must be done at parse time, since a
      --  listing can be generated in parse only mode with semantics off.

      when Pragma_Page =>
         Check_Arg_Count (0);
         List_Pragmas.Increment_Last;
         List_Pragmas.Table (List_Pragmas.Last) := (Page, Semi);

      ----------------------------------------------------------
      -- Source_File_Name and Source_File_Name_Project (GNAT) --
      ----------------------------------------------------------

      --  These two pragmas have the same syntax and semantics.
      --  There are five forms of these pragmas:

      --  pragma Source_File_Name[_Project] (
      --    [UNIT_NAME      =>] unit_NAME,
      --     BODY_FILE_NAME =>  STRING_LITERAL
      --    [, [INDEX =>] INTEGER_LITERAL]);

      --  pragma Source_File_Name[_Project] (
      --    [UNIT_NAME      =>] unit_NAME,
      --     SPEC_FILE_NAME =>  STRING_LITERAL
      --    [, [INDEX =>] INTEGER_LITERAL]);

      --  pragma Source_File_Name[_Project] (
      --     BODY_FILE_NAME  => STRING_LITERAL
      --  [, DOT_REPLACEMENT => STRING_LITERAL]
      --  [, CASING          => CASING_SPEC]);

      --  pragma Source_File_Name[_Project] (
      --     SPEC_FILE_NAME  => STRING_LITERAL
      --  [, DOT_REPLACEMENT => STRING_LITERAL]
      --  [, CASING          => CASING_SPEC]);

      --  pragma Source_File_Name[_Project] (
      --     SUBUNIT_FILE_NAME  => STRING_LITERAL
      --  [, DOT_REPLACEMENT    => STRING_LITERAL]
      --  [, CASING             => CASING_SPEC]);

      --  CASING_SPEC ::= Uppercase | Lowercase | Mixedcase

      --  Pragma Source_File_Name_Project (SFNP) is equivalent to pragma
      --  Source_File_Name (SFN), however their usage is exclusive:
      --  SFN can only be used when no project file is used, while
      --  SFNP can only be used when a project file is used.

      --  The Project Manager produces a configuration pragmas file that
      --  is communicated to the compiler with -gnatec switch. This file
      --  contains only SFNP pragmas (at least two for the default naming
      --  scheme. As this configuration pragmas file is always the first
      --  processed by the compiler, it prevents the use of pragmas SFN in
      --  other config files when a project file is in use.

      --  Note: we process this during parsing, since we need to have the
      --  source file names set well before the semantic analysis starts,
      --  since we load the spec and with'ed packages before analysis.

      when Pragma_Source_File_Name | Pragma_Source_File_Name_Project =>
         Source_File_Name : declare
            Unam  : Unit_Name_Type;
            Expr1 : Node_Id;
            Pat   : String_Ptr;
            Typ   : Character;
            Dot   : String_Ptr;
            Cas   : Casing_Type;
            Nast  : Nat;
            Expr  : Node_Id;
            Index : Nat;

            function Get_Fname (Arg : Node_Id) return Name_Id;
            --  Process file name from unit name form of pragma

            function Get_String_Argument (Arg : Node_Id) return String_Ptr;
            --  Process string literal value from argument

            procedure Process_Casing (Arg : Node_Id);
            --  Process Casing argument of pattern form of pragma

            procedure Process_Dot_Replacement (Arg : Node_Id);
            --  Process Dot_Replacement argument of patterm form of pragma

            ---------------
            -- Get_Fname --
            ---------------

            function Get_Fname (Arg : Node_Id) return Name_Id is
            begin
               String_To_Name_Buffer (Strval (Expression (Arg)));

               for J in 1 .. Name_Len loop
                  if Is_Directory_Separator (Name_Buffer (J)) then
                     Error_Msg
                       ("directory separator character not allowed",
                        Sloc (Expression (Arg)) + Source_Ptr (J));
                  end if;
               end loop;

               return Name_Find;
            end Get_Fname;

            -------------------------
            -- Get_String_Argument --
            -------------------------

            function Get_String_Argument (Arg : Node_Id) return String_Ptr is
               Str : String_Id;

            begin
               if Nkind (Expression (Arg)) /= N_String_Literal
                 and then
                  Nkind (Expression (Arg)) /= N_Operator_Symbol
               then
                  Error_Msg_N
                    ("argument for pragma% must be string literal", Arg);
                  raise Error_Resync;
               end if;

               Str := Strval (Expression (Arg));

               --  Check string has no wide chars

               for J in 1 .. String_Length (Str) loop
                  if Get_String_Char (Str, J) > 255 then
                     Error_Msg
                       ("wide character not allowed in pattern for pragma%",
                        Sloc (Expression (Arg2)) + Text_Ptr (J) - 1);
                  end if;
               end loop;

               --  Acquire string

               String_To_Name_Buffer (Str);
               return new String'(Name_Buffer (1 .. Name_Len));
            end Get_String_Argument;

            --------------------
            -- Process_Casing --
            --------------------

            procedure Process_Casing (Arg : Node_Id) is
               Expr : constant Node_Id := Expression (Arg);

            begin
               Check_Required_Identifier (Arg, Name_Casing);

               if Nkind (Expr) = N_Identifier then
                  if Chars (Expr) = Name_Lowercase then
                     Cas := All_Lower_Case;
                     return;
                  elsif Chars (Expr) = Name_Uppercase then
                     Cas := All_Upper_Case;
                     return;
                  elsif Chars (Expr) = Name_Mixedcase then
                     Cas := Mixed_Case;
                     return;
                  end if;
               end if;

               Error_Msg_N
                 ("Casing argument for pragma% must be " &
                  "one of Mixedcase, Lowercase, Uppercase",
                  Arg);
            end Process_Casing;

            -----------------------------
            -- Process_Dot_Replacement --
            -----------------------------

            procedure Process_Dot_Replacement (Arg : Node_Id) is
            begin
               Check_Required_Identifier (Arg, Name_Dot_Replacement);
               Dot := Get_String_Argument (Arg);
            end Process_Dot_Replacement;

         --  Start of processing for Source_File_Name and
         --  Source_File_Name_Project pragmas.

         begin
            if Get_Pragma_Id (Pragma_Name) = Pragma_Source_File_Name then
               if Project_File_In_Use = In_Use then
                  Error_Msg
                    ("pragma Source_File_Name cannot be used " &
                     "with a project file", Pragma_Sloc);

               else
                  Project_File_In_Use := Not_In_Use;
               end if;

            else
               if Project_File_In_Use = Not_In_Use then
                  Error_Msg
                    ("pragma Source_File_Name_Project should only be used " &
                     "with a project file", Pragma_Sloc);
               else
                  Project_File_In_Use := In_Use;
               end if;
            end if;

            --  We permit from 1 to 3 arguments

            if Arg_Count not in 1 .. 3 then
               Check_Arg_Count (1);
            end if;

            Expr1 := Expression (Arg1);

            --  If first argument is identifier or selected component, then
            --  we have the specific file case of the Source_File_Name pragma,
            --  and the first argument is a unit name.

            if Nkind (Expr1) = N_Identifier
              or else
                (Nkind (Expr1) = N_Selected_Component
                  and then
                 Nkind (Selector_Name (Expr1)) = N_Identifier)
            then
               if Nkind (Expr1) = N_Identifier
                 and then Chars (Expr1) = Name_System
               then
                  Error_Msg_N
                    ("pragma Source_File_Name may not be used for System",
                     Arg1);
                  return Error;
               end if;

               --  Process index argument if present

               if Arg_Count = 3 then
                  Expr := Expression (Arg3);

                  if Nkind (Expr) /= N_Integer_Literal
                    or else not UI_Is_In_Int_Range (Intval (Expr))
                    or else Intval (Expr) > 999
                    or else Intval (Expr) <= 0
                  then
                     Error_Msg
                       ("pragma% index must be integer literal" &
                        " in range 1 .. 999", Sloc (Expr));
                     raise Error_Resync;
                  else
                     Index := UI_To_Int (Intval (Expr));
                  end if;

               --  No index argument present

               else
                  Check_Arg_Count (2);
                  Index := 0;
               end if;

               Check_Optional_Identifier (Arg1, Name_Unit_Name);
               Unam := Get_Unit_Name (Expr1);

               Check_Arg_Is_String_Literal (Arg2);

               if Chars (Arg2) = Name_Spec_File_Name then
                  Set_File_Name
                    (Get_Spec_Name (Unam), Get_Fname (Arg2), Index);

               elsif Chars (Arg2) = Name_Body_File_Name then
                  Set_File_Name
                    (Unam, Get_Fname (Arg2), Index);

               else
                  Error_Msg_N
                    ("pragma% argument has incorrect identifier", Arg2);
                  return Pragma_Node;
               end if;

            --  If the first argument is not an identifier, then we must have
            --  the pattern form of the pragma, and the first argument must be
            --  the pattern string with an appropriate name.

            else
               if Chars (Arg1) = Name_Spec_File_Name then
                  Typ := 's';

               elsif Chars (Arg1) = Name_Body_File_Name then
                  Typ := 'b';

               elsif Chars (Arg1) = Name_Subunit_File_Name then
                  Typ := 'u';

               elsif Chars (Arg1) = Name_Unit_Name then
                  Error_Msg_N
                    ("Unit_Name parameter for pragma% must be an identifier",
                     Arg1);
                  raise Error_Resync;

               else
                  Error_Msg_N
                    ("pragma% argument has incorrect identifier", Arg1);
                  raise Error_Resync;
               end if;

               Pat := Get_String_Argument (Arg1);

               --  Check pattern has exactly one asterisk

               Nast := 0;
               for J in Pat'Range loop
                  if Pat (J) = '*' then
                     Nast := Nast + 1;
                  end if;
               end loop;

               if Nast /= 1 then
                  Error_Msg_N
                    ("file name pattern must have exactly one * character",
                     Arg1);
                  return Pragma_Node;
               end if;

               --  Set defaults for Casing and Dot_Separator parameters

               Cas := All_Lower_Case;
               Dot := new String'(".");

               --  Process second and third arguments if present

               if Arg_Count > 1 then
                  if Chars (Arg2) = Name_Casing then
                     Process_Casing (Arg2);

                     if Arg_Count = 3 then
                        Process_Dot_Replacement (Arg3);
                     end if;

                  else
                     Process_Dot_Replacement (Arg2);

                     if Arg_Count = 3 then
                        Process_Casing (Arg3);
                     end if;
                  end if;
               end if;

               Set_File_Name_Pattern (Pat, Typ, Dot, Cas);
            end if;
         end Source_File_Name;

      -----------------------------
      -- Source_Reference (GNAT) --
      -----------------------------

      --  pragma Source_Reference
      --    (INTEGER_LITERAL [, STRING_LITERAL] );

      --  Processing for this pragma must be done at parse time, since error
      --  messages needing the proper line numbers can be generated in parse
      --  only mode with semantic checking turned off, and indeed we usually
      --  turn off semantic checking anyway if any parse errors are found.

      when Pragma_Source_Reference => Source_Reference : declare
         Fname : Name_Id;

      begin
         if Arg_Count /= 1 then
            Check_Arg_Count (2);
            Check_No_Identifier (Arg2);
         end if;

         --  Check that this is first line of file. We skip this test if
         --  we are in syntax check only mode, since we may be dealing with
         --  multiple compilation units.

         if Get_Physical_Line_Number (Pragma_Sloc) /= 1
           and then Num_SRef_Pragmas (Current_Source_File) = 0
           and then Operating_Mode /= Check_Syntax
         then
            Error_Msg
              ("first % pragma must be first line of file", Pragma_Sloc);
            raise Error_Resync;
         end if;

         Check_No_Identifier (Arg1);

         if Arg_Count = 1 then
            if Num_SRef_Pragmas (Current_Source_File) = 0 then
               Error_Msg
                 ("file name required for first % pragma in file",
                  Pragma_Sloc);
               raise Error_Resync;
            else
               Fname := No_Name;
            end if;

         --  File name present

         else
            Check_Arg_Is_String_Literal (Arg2);
            String_To_Name_Buffer (Strval (Expression (Arg2)));
            Fname := Name_Find;

            if Num_SRef_Pragmas (Current_Source_File) > 0 then
               if Fname /= Full_Ref_Name (Current_Source_File) then
                  Error_Msg
                    ("file name must be same in all % pragmas", Pragma_Sloc);
                  raise Error_Resync;
               end if;
            end if;
         end if;

         if Nkind (Expression (Arg1)) /= N_Integer_Literal then
            Error_Msg
              ("argument for pragma% must be integer literal",
                Sloc (Expression (Arg1)));
            raise Error_Resync;

         --  OK, this source reference pragma is effective, however, we
         --  ignore it if it is not in the first unit in the multiple unit
         --  case. This is because the only purpose in this case is to
         --  provide source pragmas for subsequent use by gnatchop.

         else
            if Num_Library_Units = 1 then
               Register_Source_Ref_Pragma
                 (Fname,
                  Strip_Directory (Fname),
                  UI_To_Int (Intval (Expression (Arg1))),
                  Get_Physical_Line_Number (Pragma_Sloc) + 1);
            end if;
         end if;
      end Source_Reference;

      -------------------------
      -- Style_Checks (GNAT) --
      -------------------------

      --  pragma Style_Checks (On | Off | ALL_CHECKS | STRING_LITERAL);

      --  This is processed by the parser since some of the style
      --  checks take place during source scanning and parsing.

      when Pragma_Style_Checks => Style_Checks : declare
         A  : Node_Id;
         S  : String_Id;
         C  : Char_Code;
         OK : Boolean := True;

      begin
         --  Two argument case is only for semantics

         if Arg_Count = 2 then
            null;

         else
            Check_Arg_Count (1);
            Check_No_Identifier (Arg1);
            A := Expression (Arg1);

            if Nkind (A) = N_String_Literal then
               S   := Strval (A);

               declare
                  Slen    : constant Natural := Natural (String_Length (S));
                  Options : String (1 .. Slen);
                  J       : Natural;
                  Ptr     : Natural;

               begin
                  J := 1;
                  loop
                     C := Get_String_Char (S, Int (J));

                     if not In_Character_Range (C) then
                        OK := False;
                        Ptr := J;
                        exit;

                     else
                        Options (J) := Get_Character (C);
                     end if;

                     if J = Slen then
                        Set_Style_Check_Options (Options, OK, Ptr);
                        exit;

                     else
                        J := J + 1;
                     end if;
                  end loop;

                  if not OK then
                     Error_Msg
                       ("invalid style check option",
                        Sloc (Expression (Arg1)) + Source_Ptr (Ptr));
                     raise Error_Resync;
                  end if;
               end;

            elsif Nkind (A) /= N_Identifier then
               OK := False;

            elsif Chars (A) = Name_All_Checks then
               Stylesw.Set_Default_Style_Check_Options;

            elsif Chars (A) = Name_On then
               Style_Check := True;

            elsif Chars (A) = Name_Off then
               Style_Check := False;

            else
               OK := False;
            end if;

            if not OK then
               Error_Msg ("incorrect argument for pragma%", Sloc (A));
               raise Error_Resync;
            end if;
         end if;
      end Style_Checks;

      ---------------------
      -- Warnings (GNAT) --
      ---------------------

      --  pragma Warnings (On | Off, [LOCAL_NAME])

      --  The one argument case is processed by the parser, since it may
      --  control parser warnings as well as semantic warnings, and in any
      --  case we want to be absolutely sure that the range in the warnings
      --  table is set well before any semantic analysis is performed.

      when Pragma_Warnings =>
         if Arg_Count = 1 then
            Check_No_Identifier (Arg1);
            Check_Arg_Is_On_Or_Off (Arg1);

            if Chars (Expression (Arg1)) = Name_On then
               Set_Warnings_Mode_On (Pragma_Sloc);
            else
               Set_Warnings_Mode_Off (Pragma_Sloc);
            end if;
         end if;

      -----------------------
      -- All Other Pragmas --
      -----------------------

      --  For all other pragmas, checking and processing is handled
      --  entirely in Sem_Prag, and no further checking is done by Par.

      when Pragma_Abort_Defer                  |
           Pragma_AST_Entry                    |
           Pragma_All_Calls_Remote             |
           Pragma_Annotate                     |
           Pragma_Assert                       |
           Pragma_Asynchronous                 |
           Pragma_Atomic                       |
           Pragma_Atomic_Components            |
           Pragma_Attach_Handler               |
           Pragma_Compile_Time_Warning         |
           Pragma_Convention_Identifier        |
           Pragma_CPP_Class                    |
           Pragma_CPP_Constructor              |
           Pragma_CPP_Virtual                  |
           Pragma_CPP_Vtable                   |
           Pragma_C_Pass_By_Copy               |
           Pragma_Comment                      |
           Pragma_Common_Object                |
           Pragma_Complex_Representation       |
           Pragma_Component_Alignment          |
           Pragma_Controlled                   |
           Pragma_Convention                   |
           Pragma_Discard_Names                |
           Pragma_Eliminate                    |
           Pragma_Elaborate                    |
           Pragma_Elaborate_All                |
           Pragma_Elaborate_Body               |
           Pragma_Elaboration_Checks           |
           Pragma_Explicit_Overriding          |
           Pragma_Export                       |
           Pragma_Export_Exception             |
           Pragma_Export_Function              |
           Pragma_Export_Object                |
           Pragma_Export_Procedure             |
           Pragma_Export_Value                 |
           Pragma_Export_Valued_Procedure      |
           Pragma_Extend_System                |
           Pragma_External                     |
           Pragma_External_Name_Casing         |
           Pragma_Finalize_Storage_Only        |
           Pragma_Float_Representation         |
           Pragma_Ident                        |
           Pragma_Import                       |
           Pragma_Import_Exception             |
           Pragma_Import_Function              |
           Pragma_Import_Object                |
           Pragma_Import_Procedure             |
           Pragma_Import_Valued_Procedure      |
           Pragma_Initialize_Scalars           |
           Pragma_Inline                       |
           Pragma_Inline_Always                |
           Pragma_Inline_Generic               |
           Pragma_Inspection_Point             |
           Pragma_Interface                    |
           Pragma_Interface_Name               |
           Pragma_Interrupt_Handler            |
           Pragma_Interrupt_State              |
           Pragma_Interrupt_Priority           |
           Pragma_Java_Constructor             |
           Pragma_Java_Interface               |
           Pragma_Keep_Names                   |
           Pragma_License                      |
           Pragma_Link_With                    |
           Pragma_Linker_Alias                 |
           Pragma_Linker_Options               |
           Pragma_Linker_Section               |
           Pragma_Locking_Policy               |
           Pragma_Long_Float                   |
           Pragma_Machine_Attribute            |
           Pragma_Main                         |
           Pragma_Main_Storage                 |
           Pragma_Memory_Size                  |
           Pragma_No_Return                    |
           Pragma_Obsolescent                  |
           Pragma_No_Run_Time                  |
           Pragma_No_Strict_Aliasing           |
           Pragma_Normalize_Scalars            |
           Pragma_Optimize                     |
           Pragma_Optional_Overriding          |
           Pragma_Overriding                   |
           Pragma_Pack                         |
           Pragma_Passive                      |
           Pragma_Polling                      |
           Pragma_Persistent_Data              |
           Pragma_Persistent_Object            |
           Pragma_Preelaborate                 |
           Pragma_Priority                     |
           Pragma_Profile                      |
           Pragma_Propagate_Exceptions         |
           Pragma_Psect_Object                 |
           Pragma_Pure                         |
           Pragma_Pure_Function                |
           Pragma_Queuing_Policy               |
           Pragma_Remote_Call_Interface        |
           Pragma_Remote_Types                 |
           Pragma_Restrictions                 |
           Pragma_Restriction_Warnings         |
           Pragma_Restricted_Run_Time          |
           Pragma_Ravenscar                    |
           Pragma_Reviewable                   |
           Pragma_Share_Generic                |
           Pragma_Shared                       |
           Pragma_Shared_Passive               |
           Pragma_Storage_Size                 |
           Pragma_Storage_Unit                 |
           Pragma_Stream_Convert               |
           Pragma_Subtitle                     |
           Pragma_Suppress                     |
           Pragma_Suppress_All                 |
           Pragma_Suppress_Debug_Info          |
           Pragma_Suppress_Exception_Locations |
           Pragma_Suppress_Initialization      |
           Pragma_System_Name                  |
           Pragma_Task_Dispatching_Policy      |
           Pragma_Task_Info                    |
           Pragma_Task_Name                    |
           Pragma_Task_Storage                 |
           Pragma_Thread_Body                  |
           Pragma_Time_Slice                   |
           Pragma_Title                        |
           Pragma_Unchecked_Union              |
           Pragma_Unimplemented_Unit           |
           Pragma_Universal_Data               |
           Pragma_Unreferenced                 |
           Pragma_Unreserve_All_Interrupts     |
           Pragma_Unsuppress                   |
           Pragma_Use_VADS_Size                |
           Pragma_Volatile                     |
           Pragma_Volatile_Components          |
           Pragma_Weak_External                |
           Pragma_Validity_Checks              =>
         null;

      --------------------
      -- Unknown_Pragma --
      --------------------

      --  Should be impossible, since we excluded this case earlier on

      when Unknown_Pragma =>
         raise Program_Error;

   end case;

   return Pragma_Node;

   --------------------
   -- Error Handling --
   --------------------

exception
   when Error_Resync =>
      return Error;

end Prag;