[Bug c/65403] -Wno-error=<not implemented> is an error

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65403

--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
In fact, this version seems much more straightforward:

Index: opts-global.c
===================================================================
--- opts-global.c       (revision 221118)
+++ opts-global.c       (working copy)
@@ -60,13 +60,12 @@ along with GCC; see the file COPYING3.  
 #include "toplev.h"
 #include "tree-pass.h"
 #include "context.h"
 #include "asan.h"

-typedef const char *const_char_p; /* For DEF_VEC_P.  */
-
-static vec<const_char_p> ignored_options;
+static vec<const char *> ignored_options;
+static vec<const char *> ignored_wnoerror_options;

 /* Input file names.  */
 const char **in_fnames;
 unsigned num_in_fnames;

@@ -145,23 +144,35 @@ static void
 postpone_unknown_option_warning (const char *opt)
 {
   ignored_options.safe_push (opt);
 }

+/* This function is equivalent to the above, but it should be used to
+   buffer options passed to -Wno-error=.  */
+void
+postpone_unknown_wnoerror_warning (const char *opt)
+{
+  ignored_wnoerror_options.safe_push (opt);
+}
+
 /* Produce a warning for each option previously buffered.  */

 void
 print_ignored_options (void)
 {
   while (!ignored_options.is_empty ())
     {
-      const char *opt;
-
-      opt = ignored_options.pop ();
+      const char * opt = ignored_options.pop ();
       warning_at (UNKNOWN_LOCATION, 0,
                  "unrecognized command line option %qs", opt);
     }
+  while (!ignored_wnoerror_options.is_empty ())
+    {
+      const char * opt = ignored_wnoerror_options.pop ();
+      warning_at (UNKNOWN_LOCATION, 0,
+                 "-Wno-error=%s: no option -W%s", opt, opt);
+    }
 }

 /* Handle an unknown option DECODED, returning true if an error should
    be given.  */

Index: opts.c
===================================================================
--- opts.c      (revision 221118)
+++ opts.c      (working copy)
@@ -2341,11 +2341,14 @@ enable_warning_as_error (const char *arg
   new_option[0] = 'W';
   strcpy (new_option + 1, arg);
   option_index = find_opt (new_option, lang_mask);
   if (option_index == OPT_SPECIAL_unknown)
     {
-      error_at (loc, "-Werror=%s: no option -%s", arg, new_option);
+      if (value)
+       error_at (loc, "-Werror=%s: no option -%s",  arg, new_option);
+      else
+       postpone_unknown_wnoerror_warning (arg);
     }
   else
     {
       const diagnostic_t kind = value ? DK_ERROR : DK_WARNING;

Index: opts.h
===================================================================
--- opts.h      (revision 221118)
+++ opts.h      (working copy)
@@ -400,6 +400,7 @@ extern void default_options_optimization
 extern void set_struct_debug_option (struct gcc_options *opts,
                                     location_t loc,
                                     const char *value);
 extern bool opt_enum_arg_to_value (size_t opt_index, const char *arg,
                                   int *value, unsigned int lang_mask);
+extern void postpone_unknown_wnoerror_warning (const char *opt);
 #endif