--- a/gcc/plugin.c	Tue May 25 18:58:51 2010 +0900
+++ b/gcc/plugin.c	Tue Mar 22 17:18:12 2011 +0900
@@ -22,17 +22,8 @@
 
 #include "config.h"
 #include "system.h"
-
-/* If plugin support is not enabled, do not try to execute any code
-   that may reference libdl.  The generic code is still compiled in to
-   avoid including too many conditional compilation paths in the rest
-   of the compiler.  */
-#ifdef ENABLE_PLUGIN
-#include <dlfcn.h>
-#endif
-
 #include "coretypes.h"
-#include "toplev.h"
+#include "diagnostic-core.h"
 #include "tree.h"
 #include "tree-pass.h"
 #include "intl.h"
@@ -179,7 +170,7 @@
     {
       plugin = (struct plugin_name_args *) *slot;
       if (strcmp (plugin->full_name, plugin_name))
-        error ("Plugin %s was specified with different paths:\n%s\n%s",
+        error ("plugin %s was specified with different paths:\n%s\n%s",
                plugin->base_name, plugin->full_name, plugin_name);
       return;
     }
@@ -225,7 +216,7 @@
         {
           if (key_parsed)
             {
-              error ("Malformed option -fplugin-arg-%s (multiple '=' signs)",
+              error ("malformed option -fplugin-arg-%s (multiple '=' signs)",
 		     arg);
               return;
             }
@@ -241,7 +232,7 @@
 
   if (!key_start)
     {
-      error ("Malformed option -fplugin-arg-%s (missing -<key>[=<value>])",
+      error ("malformed option -fplugin-arg-%s (missing -<key>[=<value>])",
              arg);
       return;
     }
@@ -303,7 +294,7 @@
       plugin->argv[plugin->argc - 1].value = value;
     }
   else
-    error ("Plugin %s should be specified before -fplugin-arg-%s "
+    error ("plugin %s should be specified before -fplugin-arg-%s "
            "in the command line", name, arg);
 
   /* We don't need the plugin's name anymore. Just release it.  */
@@ -423,7 +414,7 @@
       default:
 	if (event < PLUGIN_EVENT_FIRST_DYNAMIC || event >= event_last)
 	  {
-	    error ("Unknown callback event registered by plugin %s",
+	    error ("unknown callback event registered by plugin %s",
 		   plugin_name);
 	    return;
 	  }
@@ -451,7 +442,7 @@
           struct callback_info *new_callback;
           if (!callback)
             {
-              error ("Plugin %s registered a null callback function "
+              error ("plugin %s registered a null callback function "
 		     "for event %s", plugin_name, plugin_event_name[event]);
               return;
             }
@@ -571,7 +562,7 @@
   dl_handle = dlopen (plugin->full_name, RTLD_NOW | RTLD_GLOBAL);
   if (!dl_handle)
     {
-      error ("Cannot load plugin %s\n%s", plugin->full_name, dlerror ());
+      error ("cannot load plugin %s\n%s", plugin->full_name, dlerror ());
       return false;
     }
 
@@ -589,7 +580,7 @@
 
   if ((err = dlerror ()) != NULL)
     {
-      error ("Cannot find %s in plugin %s\n%s", str_plugin_init_func_name,
+      error ("cannot find %s in plugin %s\n%s", str_plugin_init_func_name,
              plugin->full_name, err);
       return false;
     }
@@ -597,7 +588,7 @@
   /* Call the plugin-provided initialization routine with the arguments.  */
   if ((*plugin_init) (plugin, &gcc_version))
     {
-      error ("Fail to initialize plugin %s", plugin->full_name);
+      error ("fail to initialize plugin %s", plugin->full_name);
       return false;
     }
 
@@ -778,7 +769,7 @@
 /* Dump to FILE the names and associated events for all the active
    plugins.  */
 
-void
+DEBUG_FUNCTION void
 dump_active_plugins (FILE *file)
 {
   int event;
@@ -804,12 +795,38 @@
 
 /* Dump active plugins to stderr.  */
 
-void
+DEBUG_FUNCTION void
 debug_active_plugins (void)
 {
   dump_active_plugins (stderr);
 }
 
+/* Give a warning if plugins are present, before an ICE message asking
+   to submit a bug report.  */
+
+void
+warn_if_plugins (void)
+{
+  if (plugins_active_p ())
+    {
+      fnotice (stderr, "*** WARNING *** there are active plugins, do not report"
+	       " this as a bug unless you can reproduce it without enabling"
+	       " any plugins.\n");
+      dump_active_plugins (stderr);
+    }
+
+}
+
+/* Likewise, as a callback from the diagnostics code.  */
+
+void
+plugins_internal_error_function (diagnostic_context *context ATTRIBUTE_UNUSED,
+				 const char *msgid ATTRIBUTE_UNUSED,
+				 va_list *ap ATTRIBUTE_UNUSED)
+{
+  warn_if_plugins ();
+}
+
 /* The default version check. Compares every field in VERSION. */
 
 bool