re PR c++/83020 (('17) Class template constructor call skipped with no error…

re PR c++/83020 (('17) Class template constructor call skipped with no error when substitution fails in default argument)

2017-11-21  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/83020
	* g++.dg/cpp1z/pr83020.C: New.

From-SVN: r255006

gcc/testsuite/ChangeLog

+2017-11-21  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/83020
+	* g++.dg/cpp1z/pr83020.C: New.
+
 2017-11-21  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/82880

gcc/testsuite/g++.dg/cpp1z/pr83020.C

+// PR c++/83020
+// { dg-options -std=c++17 }
+
+struct NoDefault {
+    int val = 1234;
+    NoDefault(int v) : val(v) {}
+};
+template <class T>
+struct Whoops {
+    const char *str;
+    T obj;
+    Whoops(const char *s, T v = T()) : str(s), obj(v) {}  // { dg-error "no matching" }
+};
+const char *test() {
+    return Whoops<NoDefault>("hi").str;
+}