re PR c++/78488 (P0136R1 ICE when building call to inherited default constructor.)

	PR c++/78488
	* call.c (build_over_call): When checking ellipsis conversions for
	an inherited ctor, make sure there is at least one conversion.

	* g++.dg/cpp1z/inh-ctor37.C: New.

From-SVN: r244592

gcc/cp/ChangeLog

+2017-01-18  Nathan Sidwell  <nathan@acm.org>
+
+	PR c++/78488
+	* call.c (build_over_call): When checking ellipsis conversions for
+	an inherited ctor, make sure there is at least one conversion.
+
 2017-01-18  Jason Merrill  <jason@redhat.com>
 
 	PR c++/78894 - ICE with class deduction and default arg

gcc/cp/call.c

@@ -7899,6 +7899,7 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
 	 could handle this by open-coding the inherited constructor rather than
 	 defining it, but let's not bother now.  */
       if (!cp_unevaluated_operand
+	  && cand->num_convs
 	  && cand->convs[cand->num_convs-1]->ellipsis_p)
 	{
 	  if (complain & tf_error)

gcc/testsuite/ChangeLog

+2017-01-18  Nathan Sidwell  <nathan@acm.org>
+
+	PR c++/78488
+	* g++.dg/cpp1z/inh-ctor37.C: New.
+
 2017-01-18  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR rtl-optimization/78952

gcc/testsuite/g++.dg/cpp1z/inh-ctor37.C

+// { dg-do compile { target c++11 } }
+// PR 78488, seg fault with inherited ctor
+
+struct Foo { Foo() {} };
+
+struct Bar : Foo {
+  using Foo::Foo;
+  Bar(void*);
+};
+
+int main() {
+ Bar f;
+}