Re: [cpplib]: Implement #pragma GCC whatever

[Nathan Sidwell <nathan at codesourcery dot com>]

Zack Weinberg wrote:

> Since #pragma system_header is new and only used by libstdc++3, I
> think you should remove it from the global namespace. 
ok.
> But that can go in a separate patch.
oops, didn't notice that bit.

> Would you mind updating the documentation too?
done. I couldn't find documentation about #pragma implementation.
Also, elsewhere in cpp.texi it said `the preprocessor doesn't use pragmas'
so I fixed that one.

nathan
-- 
Dr Nathan Sidwell   ::   http://www.codesourcery.com   ::   CodeSourcery LLC
         'But that's a lie.' - 'Yes it is. What's your point?'
nathan@codesourcery.com : http://www.cs.bris.ac.uk/~nathan/ : nathan@acm.org
2000-06-23  Nathan Sidwell  <nathan@codesourcery.com>

	* cpplib.c (struct pragma_entry): New structure.
	(pragma_dispatch): Pragma dispatcher.
	(top_pragmas, gcc_pragmas): New static variables.
	(do_pragma): Use pragma_dispatch.
	(do_pragma_gcc): New pragma handler.
	* cpp.texi: Update.

Index: cpplib.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/cpplib.c,v
retrieving revision 1.177
diff -c -3 -p -r1.177 cpplib.c
*** cpplib.c	2000/06/21 23:08:17	1.177
--- cpplib.c	2000/06/23 10:53:12
*************** do_ident (pfile)
*** 789,800 ****
--- 789,839 ----
  
  /* Sub-handlers for the pragmas needing treatment here.
     They return 1 if the token buffer is to be popped, 0 if not. */
+ struct pragma_entry
+ {
+   char const *name;
+   int (*handler) PARAMS ((cpp_reader *));
+ };
+ 
+ static int pragma_dispatch             
+     PARAMS ((cpp_reader *, const struct pragma_entry *, U_CHAR *, size_t));
  static int do_pragma_once		PARAMS ((cpp_reader *));
  static int do_pragma_implementation	PARAMS ((cpp_reader *));
  static int do_pragma_poison		PARAMS ((cpp_reader *));
  static int do_pragma_system_header	PARAMS ((cpp_reader *));
  static int do_pragma_default		PARAMS ((cpp_reader *));
+ static int do_pragma_gcc                PARAMS ((cpp_reader *));
+ 
+ static const struct pragma_entry top_pragmas[] =
+ {
+   {"once", do_pragma_once},
+   {"implementation", do_pragma_implementation},
+   {"poison", do_pragma_poison},
+   {"system_header", do_pragma_system_header},
+   {"GCC", do_pragma_gcc},
+   {NULL, do_pragma_default}
+ };
+ 
+ static const struct pragma_entry gcc_pragmas[] =
+ {
+   {"implementation", do_pragma_implementation},
+   {"poison", do_pragma_poison},
+   {"system_header", do_pragma_system_header},
+   {NULL, do_pragma_default}
+ };
  
+ static int pragma_dispatch (pfile, table, p, len)
+      cpp_reader *pfile;
+      const struct pragma_entry *table;
+      U_CHAR *p;
+      size_t len;
+ {
+   for (; table->name; table++)
+     if (strlen (table->name) == len && !memcmp (p, table->name, len))
+       return (*table->handler) (pfile);
+   return (*table->handler) (pfile);
+ }
+ 
  static int
  do_pragma (pfile)
       cpp_reader *pfile;
*************** do_pragma (pfile)
*** 803,808 ****
--- 842,848 ----
    U_CHAR *buf;
    int pop;
    enum cpp_ttype token;
+   size_t  len;
  
    here = CPP_WRITTEN (pfile);
    CPP_PUTS (pfile, "#pragma ", 8);
*************** do_pragma (pfile)
*** 819,838 ****
      }
  
    buf = pfile->token_buffer + key;
    CPP_PUTC (pfile, ' ');
  
! #define tokis(x) !strncmp((char *) buf, x, sizeof(x) - 1)
!   if (tokis ("once"))
!     pop = do_pragma_once (pfile);
!   else if (tokis ("implementation"))
!     pop = do_pragma_implementation (pfile);
!   else if (tokis ("poison"))
!     pop = do_pragma_poison (pfile);
!   else if (tokis ("system_header"))
!     pop = do_pragma_system_header (pfile);
!   else
!     pop = do_pragma_default (pfile);
! #undef tokis
  
    if (_cpp_get_directive_token (pfile) != CPP_VSPACE)
      goto skip;
--- 859,868 ----
      }
  
    buf = pfile->token_buffer + key;
+   len = CPP_WRITTEN (pfile) - key;
    CPP_PUTC (pfile, ' ');
  
!   pop = pragma_dispatch (pfile, top_pragmas, buf, len);
  
    if (_cpp_get_directive_token (pfile) != CPP_VSPACE)
      goto skip;
*************** do_pragma_default (pfile)
*** 858,863 ****
--- 888,914 ----
    while (_cpp_get_directive_token (pfile) != CPP_VSPACE)
      CPP_PUTC (pfile, ' ');
    return 0;
+ }
+ 
+ static int
+ do_pragma_gcc (pfile)
+      cpp_reader *pfile;
+ {
+   long key;
+   enum cpp_ttype token;
+   U_CHAR *buf;
+   size_t  len;
+   
+   key = CPP_WRITTEN (pfile);
+   token = _cpp_get_directive_token (pfile);
+   if (token != CPP_NAME)
+     return token == CPP_VSPACE;
+ 
+   buf = pfile->token_buffer + key;
+   len = CPP_WRITTEN (pfile) - key;
+   CPP_PUTC (pfile, ' ');
+   
+   return pragma_dispatch (pfile, gcc_pragmas, buf, len);
  }
  
  static int
Index: cpp.texi
===================================================================
RCS file: /cvs/gcc/egcs/gcc/cpp.texi,v
retrieving revision 1.21
diff -c -3 -p -r1.21 cpp.texi
*** cpp.texi	2000/05/18 11:09:26	1.21
--- cpp.texi	2000/06/23 10:53:14
*************** command line.  If the same directory is 
*** 613,625 ****
  @samp{-isystem}, @samp{-I} wins; it is as if the @samp{-isystem} option
  had never been specified at all.
  
! @findex #pragma system_header
! There is also a directive, @samp{#pragma system_header}, which tells GCC
  to consider the rest of the current include file a system header, no
  matter where it was found.  Code that comes before the @samp{#pragma} in
  the file will not be affected.
  
! @samp{#pragma system_header} has no effect in the primary source file.
  
  @node Macros, Conditionals, Header Files, Top
  @section Macros
--- 613,625 ----
  @samp{-isystem}, @samp{-I} wins; it is as if the @samp{-isystem} option
  had never been specified at all.
  
! @findex #pragma GCC system_header
! There is also a directive, @samp{#pragma GCC system_header}, which tells GCC
  to consider the rest of the current include file a system header, no
  matter where it was found.  Code that comes before the @samp{#pragma} in
  the file will not be affected.
  
! @samp{#pragma GCC system_header} has no effect in the primary source file.
  
  @node Macros, Conditionals, Header Files, Top
  @section Macros
*************** Recall that a comment counts as whitespa
*** 1503,1526 ****
  @node Poisoning, Macro Pitfalls, Redefining, Macros
  @subsection Poisoning Macros
  @cindex poisoning macros
  
  Sometimes, there is an identifier that you want to remove completely
  from your program, and make sure that it never creeps back in.  To
! enforce this, the @samp{#pragma poison} directive can be used.
! @samp{#pragma poison} is followed by a list of identifiers to poison,
  and takes effect for the rest of the source.  You cannot @samp{#undef} a
  poisoned identifier or test to see if it's defined with @samp{#ifdef}.
  
  For example,
  
  @example
! #pragma poison printf sprintf fprintf
  sprintf(some_string, "hello");
  @end example
  
  @noindent
  will produce an error.
  
  @node Macro Pitfalls,, Poisoning, Macros
  @subsection Pitfalls and Subtleties of Macros
  @cindex problems with macros
--- 1503,1530 ----
  @node Poisoning, Macro Pitfalls, Redefining, Macros
  @subsection Poisoning Macros
  @cindex poisoning macros
+ @findex #pragma GCC poison
+ @findex #pragma poison
  
  Sometimes, there is an identifier that you want to remove completely
  from your program, and make sure that it never creeps back in.  To
! enforce this, the @samp{#pragma GCC poison} directive can be used.
! @samp{#pragma GCC poison} is followed by a list of identifiers to poison,
  and takes effect for the rest of the source.  You cannot @samp{#undef} a
  poisoned identifier or test to see if it's defined with @samp{#ifdef}.
  
  For example,
  
  @example
! #pragma GCC poison printf sprintf fprintf
  sprintf(some_string, "hello");
  @end example
  
  @noindent
  will produce an error.
  
+ For backwards compatibility @samp{#pragma poison} is also recognized.
+ 
  @node Macro Pitfalls,, Poisoning, Macros
  @subsection Pitfalls and Subtleties of Macros
  @cindex problems with macros
*************** rather than a line of output containing 
*** 2637,2647 ****
  some old C programs contain such lines.
  
  @findex #pragma
  The ANSI standard specifies that the effect of the @samp{#pragma}
! directive is implementation-defined.  In the GNU C preprocessor,
! @samp{#pragma} directives are not used, except for @samp{#pragma once}
! (@pxref{Once-Only}).  However, they are left in the preprocessor output,
! so they are available to the compilation pass.
  
  @findex #ident
  The @samp{#ident} directive is supported for compatibility with certain
--- 2641,2655 ----
  some old C programs contain such lines.
  
  @findex #pragma
+ @findex #pragma GCC
+ 
  The ANSI standard specifies that the effect of the @samp{#pragma}
! directive is implementation-defined.  The GNU C preprocessor recognizes
! some pragmas, and passes unrecognized ones through to the preprocessor
! output, so they are available to the compilation pass.  GNU C preprocessor
! pragmas are of the form @samp{#pragma GCC ...}. For backwards
! compatibility previously supported pragmas are also recognized without
! the @samp{GCC}, however that use is deprecated.
  
  @findex #ident
  The @samp{#ident} directive is supported for compatibility with certain