Fix ICE on invalid variable template instantiation (PR c++/72759)

gcc/cp/ChangeLog:

	PR c++/72759
	* pt.c (tsubst_qualified_id): Return error_mark_node if
	template_args is error_mark_node.

gcc/testsuite/ChangeLog:

	PR c++/72759
	* g++.dg/cpp1y/pr72759.C: New test.

From-SVN: r239147

gcc/cp/ChangeLog

+2016-08-04  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR c++/72759
+	* pt.c (tsubst_qualified_id): Return error_mark_node if
+	template_args is error_mark_node.
+
 2016-08-04  Jason Merrill  <jason@redhat.com>
 
 	PR c++/72415

gcc/cp/pt.c

@@ -13832,6 +13832,8 @@ tsubst_qualified_id (tree qualified_id, tree args,
       if (template_args)
 	template_args = tsubst_template_args (template_args, args,
 					      complain, in_decl);
+      if (template_args == error_mark_node)
+	return error_mark_node;
       name = TREE_OPERAND (name, 0);
     }
   else

gcc/testsuite/ChangeLog

 2016-08-04  Patrick Palka  <ppalka@gcc.gnu.org>
 
+	PR c++/72759
+	* g++.dg/cpp1y/pr72759.C: New test.
+
+2016-08-04  Patrick Palka  <ppalka@gcc.gnu.org>
+
 	* gcc.dg/switch-10.c: New test.
 
 2016-08-04  James Greenhalgh  <james.greenhalgh@arm.com>

gcc/testsuite/g++.dg/cpp1y/pr72759.C

+// PR c++/72759
+// { dg-do compile { target c++14 } }
+
+template <typename> struct SpecPerType;
+class Specializer {
+  public:  template <bool> static void MbrFnTempl();
+  template <unsigned> struct A { static void InnerMemberFn(); };
+  void Trigger() { A<0>::InnerMemberFn; }
+};
+template <> struct SpecPerType<Specializer> {
+  using FnType = void *;
+  template <bool P>
+  static constexpr FnType SpecMbrFnPtr = Specializer::MbrFnTempl<P>;
+};
+template <unsigned X> void Specializer::A<X>::InnerMemberFn() {
+  using Spec = SpecPerType<Specializer>;
+  Spec ErrorSite = Spec::SpecMbrFnPtr<SpecMbrFnPtr>;  // { dg-error "not declared" }
+}