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

[Martin Liška <mliska at suse dot cz>]

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


diff --git a/gcc/opts-common.c b/gcc/opts-common.c
index 660dfe63858..76285bdcf93 100644
--- a/gcc/opts-common.c
+++ b/gcc/opts-common.c
@@ -537,7 +537,8 @@ decode_cmdline_option (const char **argv, unsigned int lang_mask,
 
   extra_args = 0;
 
-  opt_index = find_opt (argv[0] + 1, lang_mask);
+  const char *opt_value = argv[0] + 1;
+  opt_index = find_opt (opt_value, lang_mask);
   i = 0;
   while (opt_index == OPT_SPECIAL_unknown
 	 && i < ARRAY_SIZE (option_map))
@@ -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.  */
+      char *werror_arg = xstrdup (opt_value + 6);
+      werror_arg[0] = 'W';
+
+      size_t warning_index = find_opt (werror_arg, lang_mask);
+      if (warning_index != OPT_SPECIAL_unknown)
+	{
+	  const struct cl_option *warning_option
+	    = &cl_options[warning_index];
+	  if (!option_ok_for_language (warning_option, lang_mask))
+	    errors |= CL_ERR_WRONG_LANG;
+	}
+    }
 
   /* Convert the argument to lowercase if appropriate.  */
   if (arg && option->cl_tolower)
diff --git a/gcc/opts-global.c b/gcc/opts-global.c
index bf4db775928..f62d6a3cddb 100644
--- a/gcc/opts-global.c
+++ b/gcc/opts-global.c
@@ -103,10 +103,14 @@ complain_wrong_lang (const struct cl_decoded_option *decoded,
 	   text, bad_lang);
   else if (lang_mask == CL_DRIVER)
     gcc_unreachable ();
-  else
+  else if (ok_langs[0] != '\0')
     /* Eventually this should become a hard error IMO.  */
     warning (0, "command-line option %qs is valid for %s but not for %s",
 	     text, ok_langs, bad_lang);
+  else
+    /* Happens for -Werror=warning_name.  */
+    warning (0, "command-line error argument %qs is not valid for %s",
+	     text, bad_lang);
 
   free (ok_langs);
   free (bad_lang);
diff --git a/gcc/testsuite/gcc.dg/pr91172.c b/gcc/testsuite/gcc.dg/pr91172.c
new file mode 100644
index 00000000000..bf62d94d8a2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr91172.c
@@ -0,0 +1,3 @@
+/* { dg-do compile } */
+/* { dg-options "-Werror=target-lifetime" } */
+/* { dg-warning "command-line error argument '-Werror=target-lifetime' is not valid for C" "" { target *-*-* } 0 } */