* error.c (type_to_string): Avoid redundant akas.

From-SVN: r175833

gcc/cp/ChangeLog

+2011-07-04  Jason Merrill  <jason@redhat.com>
+
+	* error.c (type_to_string): Avoid redundant akas.
+
 2011-07-01  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
 	PR c++/49605

gcc/cp/error.c

@@ -2634,14 +2634,28 @@ type_to_string (tree typ, int verbose)
 
   reinit_cxx_pp ();
   dump_type (typ, flags);
+  /* If we're printing a type that involves typedefs, also print the
+     stripped version.  But sometimes the stripped version looks
+     exactly the same, so we don't want it after all.  To avoid printing
+     it in that case, we play ugly obstack games.  */
   if (typ && TYPE_P (typ) && typ != TYPE_CANONICAL (typ)
       && !uses_template_parms (typ))
     {
+      int aka_start; char *p;
+      struct obstack *ob = pp_base (cxx_pp)->buffer->obstack;
+      /* Remember the end of the initial dump.  */
+      int len = obstack_object_size (ob);
       tree aka = strip_typedefs (typ);
       pp_string (cxx_pp, " {aka");
       pp_cxx_whitespace (cxx_pp);
+      /* And remember the start of the aka dump.  */
+      aka_start = obstack_object_size (ob);
       dump_type (aka, flags);
       pp_character (cxx_pp, '}');
+      p = (char*)obstack_base (ob);
+      /* If they are identical, cut off the aka with a NUL.  */
+      if (memcmp (p, p+aka_start, len) == 0)
+	p[len] = '\0';
     }
   return pp_formatted_text (cxx_pp);
 }

gcc/testsuite/ChangeLog

+2011-07-04  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/diagnostic/aka1.C: New.
+
 2011-07-04  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/49619

gcc/testsuite/g++.dg/diagnostic/aka1.C

+// Basic test for typedef stripping in diagnostics.
+
+struct A {
+  void f();
+};
+
+void A::f() {
+  // We don't want an aka for the injected-class-name.
+  A a = 0;			// { dg-error "type .A. requested" }
+}
+
+typedef A B;
+
+// We do want an aka for a real typedef.
+B b = 0;			// { dg-error "B .aka A." }