[PATCH] Make a warning for -Werror=wrong-language (PR driver/91172).

[Martin Sebor]

On 7/16/19 5:16 AM, Martin Liška wrote:
> Hi.
> 
> I noticed in the PR that -Werror=argument argument is not verified
> that the option is supported by a language we compile for.
> That's changed in the patch. However, it's not ideal as I need to mark
> the -Werror as the problematic option and one can't print a proper
> list of valid languages for which the rejected option can be used.
> 
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> 
> Ready to be installed?
> Thanks,
> Martin
> 
> gcc/ChangeLog:
> 
> 2019-07-16  Martin Liska  <mliska@suse.cz>
> 
> 	PR driver/91172
> 	* opts-common.c (decode_cmdline_option): Decode
> 	argument of -Werror and check it for a wrong language.
> 	* opts-global.c (complain_wrong_lang): Remove such case.
> 
> gcc/testsuite/ChangeLog:
> 
> 2019-07-16  Martin Liska  <mliska@suse.cz>
> 
> 	PR driver/91172
> 	* gcc.dg/pr91172.c: New test.
> ---
>   gcc/opts-common.c              | 20 +++++++++++++++++++-
>   gcc/opts-global.c              |  6 +++++-
>   gcc/testsuite/gcc.dg/pr91172.c |  3 +++
>   3 files changed, 27 insertions(+), 2 deletions(-)
>   create mode 100644 gcc/testsuite/gcc.dg/pr91172.c

Nice catch!

@@ -745,6 +746,23 @@ decode_cmdline_option (const char **argv, unsigned 
int lang_mask,
    /* Check if this is a switch for a different front end.  */
    if (!option_ok_for_language (option, lang_mask))
      errors |= CL_ERR_WRONG_LANG;
+  else if (strcmp (option->opt_text, "-Werror=") == 0
+	   && strchr (opt_value, ',') == NULL)
+    {
+      /* Verify that -Werror argument is a valid warning
+	 for a languages.  */

Typo: "for a language" (singular).

+  else
+    /* Happens for -Werror=warning_name.  */
+    warning (0, "command-line error argument %qs is not valid for %s",
+	     text, bad_lang);

It might be better phrased as something like

   "%<-Werror=%> argument %qs is not valid for %s"

The argument is not one of a "command-line error."  It's one
to the -Werror option (which can be specified in other places
besides the command line).

Martin