PR c++/51194 - ICE with invalid alias template

gcc/cp/

	PR c++/51194
	* pt.c (lookup_template_class_1): Go out early if the type of the
	template is error_mark_node.

gcc/testsuite/

	PR c++/51194
	* g++.dg/cpp0x/alias-decl-15.C: New test.

From-SVN: r181523

gcc/cp/ChangeLog

+2011-11-20  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/51194
+	* pt.c (lookup_template_class_1): Go out early if the type of the
+	template is error_mark_node.
+
 2011-11-19  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/51216

gcc/cp/pt.c

@@ -7270,6 +7270,12 @@ lookup_template_class_1 (tree d1, tree arglist, tree in_decl, tree context,
       int is_dependent_type;
       int use_partial_inst_tmpl = false;
 
+      if (template_type == error_mark_node)
+	/* An error occured while building the template TEMPL, and a
+	   diagnostic has most certainly been emitted for that
+	   already.  Let's propagate that error.  */
+	return error_mark_node;
+
       gen_tmpl = most_general_template (templ);
       parmlist = DECL_TEMPLATE_PARMS (gen_tmpl);
       parm_depth = TMPL_PARMS_DEPTH (parmlist);

gcc/testsuite/ChangeLog

+2011-11-20  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/51194
+	* g++.dg/cpp0x/alias-decl-15.C: New test.
+
 2011-11-19  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/51216

gcc/testsuite/g++.dg/cpp0x/alias-decl-15.C

+// Origin PR c++/51194
+// { dg-options "-std=c++0x" }
+
+template<class U, class V> //#1
+struct foo {}; // { dg-error "provided for|foo" }
+
+template<class U, class V=char>
+struct P {};
+
+template<template<class... U> class... TT>
+struct bar {
+    template<class... Args>
+    using mem = P<TT<Args...>...>;//#2 { dg-error "wrong number of|arguments" }
+};
+
+bar<foo>::mem<int, char> b;//#3 { dg-error "invalid type" }
+