--- gcc-6.4.0-orig/gcc/gcc.c	2017-07-24 16:03:41.289357730 +0100
+++ gcc-6.4.0/gcc/gcc.c	2017-07-24 16:23:05.637928450 +0100
@@ -299,6 +299,10 @@
 static const char *cross_compile = "0";
 #endif
 
+/* The lang specs might wish to override the default linker.
+ */
+int allow_linker = 1;
+
 /* Greatest exit code of sub-processes that has been encountered up to
    now.  */
 static int greatest_status = 1;
@@ -403,6 +407,7 @@
 static const char *replace_extension_spec_func (int, const char **);
 static const char *greater_than_spec_func (int, const char **);
 static char *convert_white_space (char *);
+static void handle_OPT_B (const char *arg);
 
 /* The Specs Language
 
@@ -1007,6 +1012,7 @@
 /* We pass any -flto flags on to the linker, which is expected
    to understand them.  In practice, this means it had better be collect2.  */
 /* %{e*} includes -export-dynamic; see comment in common.opt.  */
+
 #ifndef LINK_COMMAND_SPEC
 #define LINK_COMMAND_SPEC "\
 %{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
@@ -1633,6 +1639,10 @@
   { 0, 0 }
 };
 
+/* front end registered spec functions */
+static struct spec_function *lang_spec_functions = NULL;
+static unsigned int lang_spec_functions_length = 0;
+
 static int processing_spec_function;
 
 /* Add appropriate libgcc specs to OBSTACK, taking into account
@@ -3541,6 +3551,68 @@
   n_switches++;
 }
 
+/* Save an option OPT with N_ARGS arguments in array ARGS, marking it
+   as validated if VALIDATED.  */
+
+void
+fe_save_switch (const char *opt, size_t n_args, const char *const *args,
+		bool validated, bool known)
+{
+  save_switch (opt, n_args, args, validated, known);
+}
+
+void fe_B_prefix (const char *arg)
+{
+  handle_OPT_B (arg);
+}
+
+void
+fe_add_linker_option (const char *option)
+{
+  add_linker_option (option, strlen (option));
+}
+
+/*  Handle the -B option by adding the prefix to exec, startfile and
+    include search paths.  */
+
+static
+void handle_OPT_B (const char *arg)
+{
+  size_t len = strlen (arg);
+  
+  /* Catch the case where the user has forgotten to append a
+     directory separator to the path.  Note, they may be using
+     -B to add an executable name prefix, eg "i386-elf-", in
+     order to distinguish between multiple installations of
+     GCC in the same directory.  Hence we must check to see
+     if appending a directory separator actually makes a
+     valid directory name.  */
+  if (!IS_DIR_SEPARATOR (arg[len - 1])
+      && is_directory (arg, false))
+    {
+      char *tmp = XNEWVEC (char, len + 2);
+      strcpy (tmp, arg);
+      tmp[len] = DIR_SEPARATOR;
+      tmp[++len] = 0;
+      arg = tmp;
+    }
+
+  add_prefix (&exec_prefixes, arg, NULL,
+	      PREFIX_PRIORITY_B_OPT, 0, 0);
+  add_prefix (&startfile_prefixes, arg, NULL,
+	      PREFIX_PRIORITY_B_OPT, 0, 0);
+  add_prefix (&include_prefixes, arg, NULL,
+	      PREFIX_PRIORITY_B_OPT, 0, 0);
+}
+
+/* Save the infile */
+
+void
+fe_add_infile (const char *infile, const char *lang)
+{
+  add_infile (infile, lang);
+}
+
 /* Handle an option DECODED that is unknown to the option-processing
    machinery.  */
 
@@ -4004,33 +4076,7 @@
       break;
 
     case OPT_B:
-      {
-	size_t len = strlen (arg);
-
-	/* Catch the case where the user has forgotten to append a
-	   directory separator to the path.  Note, they may be using
-	   -B to add an executable name prefix, eg "i386-elf-", in
-	   order to distinguish between multiple installations of
-	   GCC in the same directory.  Hence we must check to see
-	   if appending a directory separator actually makes a
-	   valid directory name.  */
-	if (!IS_DIR_SEPARATOR (arg[len - 1])
-	    && is_directory (arg, false))
-	  {
-	    char *tmp = XNEWVEC (char, len + 2);
-	    strcpy (tmp, arg);
-	    tmp[len] = DIR_SEPARATOR;
-	    tmp[++len] = 0;
-	    arg = tmp;
-	  }
-
-	add_prefix (&exec_prefixes, arg, NULL,
-		    PREFIX_PRIORITY_B_OPT, 0, 0);
-	add_prefix (&startfile_prefixes, arg, NULL,
-		    PREFIX_PRIORITY_B_OPT, 0, 0);
-	add_prefix (&include_prefixes, arg, NULL,
-		    PREFIX_PRIORITY_B_OPT, 0, 0);
-      }
+      handle_OPT_B (arg);
       validated = true;
       break;
 
@@ -5928,6 +5974,33 @@
   return 0;
 }
 
+/* Allow the front end to register a spec function.  */
+
+void fe_add_spec_function (const char *name, const char *(*func) (int, const char **))
+{
+  const struct spec_function *f = lookup_spec_function (name);
+  struct spec_function *fl;
+  unsigned int i;
+
+  if (f != NULL)
+    fatal_error (input_location, "spec function (%s) already registered", name);
+
+  if (lang_spec_functions == NULL)
+    lang_spec_functions_length = 1;
+
+  lang_spec_functions_length++;
+  fl = (struct spec_function *) xmalloc (sizeof (const struct spec_function)*lang_spec_functions_length);
+  for (i=0; i<lang_spec_functions_length-2; i++)
+    fl[i] = lang_spec_functions[i];
+  free (lang_spec_functions);
+  lang_spec_functions = fl;
+
+  lang_spec_functions[lang_spec_functions_length-2].name = name;
+  lang_spec_functions[lang_spec_functions_length-2].func = func;
+  lang_spec_functions[lang_spec_functions_length-1].name = NULL;
+  lang_spec_functions[lang_spec_functions_length-1].func = NULL;
+}
+
 /* Look up a spec function.  */
 
 static const struct spec_function *
@@ -5939,6 +6012,11 @@
     if (strcmp (sf->name, name) == 0)
       return sf;
 
+  if (lang_spec_functions != NULL)
+    for (sf = lang_spec_functions; sf->name != NULL; sf++)
+      if (strcmp (sf->name, name) == 0)
+	return sf;
+
   return NULL;
 }
 
@@ -7381,6 +7459,8 @@
 			   accel_dir_suffix, dir_separator_str, NULL);
   just_machine_suffix = concat (spec_machine, dir_separator_str, NULL);
 
+  lang_register_spec_functions ();
+
   specs_file = find_a_file (&startfile_prefixes, "specs", R_OK, true);
   /* Read the specs file unless it is a default one.  */
   if (specs_file != 0 && strcmp (specs_file, "specs"))
@@ -8173,7 +8253,8 @@
 
   /* Run ld to link all the compiler output files.  */
 
-  if (num_linker_inputs > 0 && !seen_error () && print_subprocess_help < 2)
+  if (num_linker_inputs > 0 && !seen_error () && print_subprocess_help < 2
+      && allow_linker)
     {
       int tmp = execution_count;
 
@@ -8240,7 +8321,7 @@
   /* If options said don't run linker,
      complain about input files to be given to the linker.  */
 
-  if (! linker_was_run && !seen_error ())
+  if (! linker_was_run && !seen_error () && allow_linker)
     for (i = 0; (int) i < n_infiles; i++)
       if (explicit_link_files[i]
 	  && !(infiles[i].language && infiles[i].language[0] == '*'))
