Re: named warnings & individual warning control

[DJ Delorie <dj at redhat dot com>]

> Note that you could get some of the same benefits by just adding the
> #pragmas for the current warning groups,

Partial patch (proof of concept, missing docs, changelog, etc), only
works for options with the Var() syntax...  Comments?

I thought of extending this to call the handle_option langhook for
non-Var entries but it was difficult to determine if/when that's safe.

Also, -O[23] tends to confuse this as they defer the use of warning
flags until after the whole file is parsed, so pragmas between
function definitions don't do what you expect :-(

Index: c-pragma.c
===================================================================
RCS file: /greed/dj/gnu/gcc/repository/gcc/gcc/c-pragma.c,v
retrieving revision 1.71
diff -p -C2 -r1.71 c-pragma.c
*** c-pragma.c	22 Jun 2004 06:51:50 -0000	1.71
--- c-pragma.c	24 Jun 2004 22:04:58 -0000
*************** Software Foundation, 59 Temple Place - S
*** 36,39 ****
--- 36,40 ----
  #include "tm_p.h"
  #include "target.h"
+ #include "opts.h"
  
  #define GCC_BAD(msgid) do { warning (msgid); return; } while (0)
*************** c_register_pragma (const char *space, co
*** 576,579 ****
--- 577,634 ----
  }
  
+ static void
+ handle_pragma_gcc_warning (cpp_reader *dummy ATTRIBUTE_UNUSED)
+ {
+   tree type, x;
+   const char *ts;
+   char *ent;
+   int len, flag_val;
+   unsigned int i;
+   static int list_printed = 0;
+ 
+   if (c_lex (&type) != CPP_STRING)
+     {
+       warning ("malformed #pragma GCC warning, ignored");
+       return;
+     }
+   ts = TREE_STRING_POINTER (type);
+   if (c_lex (&x) != CPP_EOF)
+     warning ("junk at end of #pragma GCC warning");
+ 
+   len = strlen (ts);
+   ent = (char *) xmalloc (len + 3);
+   ent[0] = '-';
+   ent[1] = 'W';
+   if (strncmp (ts, "no-", 3) == 0)
+     {
+       flag_val = 0;
+       strcpy (ent+2, ts+3);
+     }
+   else
+     {
+       flag_val = 1;
+       strcpy (ent+2, ts);
+     }
+ 
+   for (i=0; i<cl_options_count; i++)
+     if (cl_options[i].flag_var
+ 	&& strcmp (cl_options[i].opt_text, ent) == 0)
+       {
+ 	*cl_options[i].flag_var = flag_val;
+ 	return;
+       }
+   warning ("pragma GCC warning: `%s' not found, ignored", ent);
+ 
+   if (list_printed)
+     return;
+   list_printed = 1;
+ 
+   inform ("Available warnings are:");
+   for (i=0; i<cl_options_count; i++)
+     if (cl_options[i].flag_var
+ 	&& strncmp (cl_options[i].opt_text, "-W", 2) == 0)
+       inform ("  %s", cl_options[i].opt_text);
+ }
+ 
  /* Set up front-end pragmas.  */
  void
*************** init_pragma (void)
*** 595,598 ****
--- 650,655 ----
    REGISTER_TARGET_PRAGMAS ();
  #endif
+ 
+   c_register_pragma ("GCC", "warning", handle_pragma_gcc_warning);
  }