fdiagnostics-color=never does not disable color for some diagnostics

Actually, I was trying to reject non-warning options as argument to
-Werror=. However, the new test fails because -fdiagnostics-color=never is
always placed by the driver after the warning options when calling the compiler
proper. This patch prunes all -fdiagnostics-color from the command-line but the
last one, which is moved to the first position.

gcc/ChangeLog:

2015-09-24  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR driver/67640
	* opts-common.c (prune_options): Discard all -fdiagnostics-color
	but the last one, which is moved to the front to be processed
	first.
	* opts.c (enable_warning_as_error): Reject options that do not
	control warnings.

gcc/testsuite/ChangeLog:

2015-09-24  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR driver/67640
	* gcc.dg/Werror-13.c: New test.

From-SVN: r228094

gcc/ChangeLog

+2015-09-24  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR driver/67640
+	* opts-common.c (prune_options): Discard all -fdiagnostics-color
+	but the last one, which is moved to the front to be processed
+	first.
+	* opts.c (enable_warning_as_error): Reject options that do not
+	control warnings.
+
 2015-09-24  Jiong Wang  <jiong.wang@arm.com>
 
 	* config/aarch64/aarch64.c (aarch64_print_operand): Add "CONST" support.

gcc/opts-common.c

@@ -825,6 +825,7 @@ prune_options (struct cl_decoded_option **decoded_options,
     = XNEWVEC (struct cl_decoded_option, old_decoded_options_count);
   unsigned int i;
   const struct cl_option *option;
+  unsigned int fdiagnostics_color_idx = 0;
 
   /* Remove arguments which are negated by others after them.  */
   new_decoded_options_count = 0;
@@ -844,6 +845,11 @@ prune_options (struct cl_decoded_option **decoded_options,
 	case OPT_SPECIAL_input_file:
 	  goto keep;
 
+	/* Do not save OPT_fdiagnostics_color_, just remember the last one.  */
+	case OPT_fdiagnostics_color_:
+	  fdiagnostics_color_idx = i;
+	  continue;
+
 	default:
 	  gcc_assert (opt_idx < cl_options_count);
 	  option = &cl_options[opt_idx];
@@ -879,6 +885,17 @@ keep:
 	}
     }
 
+  if (fdiagnostics_color_idx > 1)
+    {
+      /* We put the last -fdiagnostics-color= at the first position
+	 after argv[0] so it can take effect immediately.  */
+      memmove (new_decoded_options + 2, new_decoded_options + 1,
+	       sizeof (struct cl_decoded_option) 
+	       * (new_decoded_options_count - 1));
+      new_decoded_options[1] = old_decoded_options[fdiagnostics_color_idx];
+      new_decoded_options_count++;
+    }
+
   free (old_decoded_options);
   new_decoded_options = XRESIZEVEC (struct cl_decoded_option,
 				    new_decoded_options,

gcc/opts.c

@@ -2359,9 +2359,10 @@ enable_warning_as_error (const char *arg, int value, unsigned int lang_mask,
   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);
-    }
+    error_at (loc, "-Werror=%s: no option -%s", arg, new_option);
+  else if (!(cl_options[option_index].flags & CL_WARNING))
+    error_at (loc, "-Werror=%s: -%s is not an option that controls warnings",
+	      arg, new_option);
   else
     {
       const diagnostic_t kind = value ? DK_ERROR : DK_WARNING;

gcc/testsuite/ChangeLog

+2015-09-24  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR driver/67640
+	* gcc.dg/Werror-13.c: New test.
+
 2015-09-24  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	* gcc.target/aarch64/target_attr_10.c (foo): Use dg-message for note.

gcc/testsuite/gcc.dg/Werror-13.c

+/* { dg-do compile } */
+/* { dg-options "-Werror=error -Werror=p, -Werror=l, -Werror=fatal-errors" } */
+/* { dg-error "-Wp, is not an option that controls warnings" "" { target *-*-* } 0 } */
+/* { dg-error "-Wl, is not an option that controls warnings" "" { target *-*-* } 0 } */
+/* { dg-error "-Werror is not an option that controls warnings" "" { target *-*-* } 0 } */
+/* { dg-error "-Wfatal-errors is not an option that controls warnings" "" { target *-*-* } 0 } */
+
+int i;