Index: gcc/d/d-lang.cc
--- gcc/d/d-lang.cc.orig
+++ gcc/d/d-lang.cc
@@ -1964,6 +1964,12 @@ const scoped_attribute_specs *const d_langhook_attribu
   &d_langhook_common_attribute_table,
 };
 
+extern "C" const char *
+fname_as_string(int pretty_p __attribute__((__unused__)))
+{
+	return NULL;
+}
+
 /* Definitions for our language-specific hooks.  */
 
 #undef LANG_HOOKS_NAME
