PR c++/78906 - ICE with member variable template

	* pt.c (finish_template_variable): Use most_general_template.

From-SVN: r243897

gcc/cp/ChangeLog

 2016-12-22  Jason Merrill  <jason@redhat.com>
 
+	PR c++/78906
+	* pt.c (finish_template_variable): Use most_general_template.
+
 	PR c++/78898
 	PR c++/42329
 	* pt.c (unify): Don't look for a class template from a non-class.

gcc/cp/pt.c

@@ -9000,6 +9000,7 @@ finish_template_variable (tree var, tsubst_flags_t complain)
   tree tmpl_args = DECL_TI_ARGS (DECL_TEMPLATE_RESULT (templ));
   arglist = add_outermost_template_args (tmpl_args, arglist);
 
+  templ = most_general_template (templ);
   tree parms = DECL_TEMPLATE_PARMS (templ);
   arglist = coerce_innermost_template_parms (parms, arglist, templ, complain,
 					     /*req_all*/true,

gcc/testsuite/g++.dg/cpp1y/var-templ54.C

+// PR c++/78906
+// { dg-do compile { target c++14 } }
+
+template <typename> struct A { static constexpr int digits = 0; };
+template <typename> struct B {
+  template <int, typename MaskInt = int, int = A<MaskInt>::digits>
+  static constexpr int XBitMask = 0;
+};
+struct C {
+  using ReferenceHost = B<int>;
+  template <int> static decltype(ReferenceHost::XBitMask<0>) XBitMask;
+};
+int main() { C::XBitMask<0>; }