[Ada] Issue a warning for -gstabs

[Eric Botcazou]

We are phasing out the GNAT encoding scheme in the debugging information so 
STABS is considered obsolete for Ada.

Tested on x86_64-suse-linux, applied on the mainline.


2015-09-14  Pierre-Marie de Rodat  <dero...@adacore.com>

        * gcc-interface/misc.c (gnat_post_options): Issue a warning if
        generating STABS debugging information when not the default.

-- 
Eric Botcazou
Index: gcc-interface/misc.c
===================================================================
--- gcc-interface/misc.c	(revision 227736)
+++ gcc-interface/misc.c	(working copy)
@@ -268,6 +268,13 @@ gnat_post_options (const char **pfilenam
   if (!global_options_set.x_flag_diagnostics_show_caret)
     global_dc->show_caret = false;
 
+  /* Warn only if STABS is not the default: we don't want to emit a warning if
+     the user did not use a -gstabs option.  */
+  if (PREFERRED_DEBUGGING_TYPE != DBX_DEBUG && write_symbols == DBX_DEBUG)
+    warning (0, "STABS debugging information for Ada is obsolete and not "
+		"supported anymore");
+
+  /* Copy global settings to local versions.  */
   optimize = global_options.x_optimize;
   optimize_size = global_options.x_optimize_size;
   flag_compare_debug = global_options.x_flag_compare_debug;