--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp1y/pr79937-5.C	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,42 @@
+// PR c++/79937
+// This is a constexpr adaptation of pr79937-3.C and pr79937-4.C.
+// { dg-do compile { target c++14 } }
+
+struct X {
+  unsigned i;
+  unsigned n = i;
+};
+
+constexpr X bar(X x) {
+  return x;
+}
+
+struct Y
+{
+  static constexpr Y bar(Y y) { return y; }
+  unsigned i;
+  unsigned n = bar(Y{2,i}).n;
+};
+
+constexpr X x { 1, bar(X{2}).n };
+static_assert(x.n == 2, "");
+
+constexpr Y y { 1 };
+static_assert(y.n == 1, "");
+
+struct Z {
+  unsigned i;
+  unsigned n = i;
+  unsigned m = i;
+};
+
+constexpr Z
+baz (Z z)
+{
+  if (z.i != 1 || z.n != 2 || z.m != 1)
+    __builtin_abort ();
+  return z;
+}
+
+constexpr Z z = baz (Z {1, Z {2}.n});
+static_assert(z.i == 1 && z.n == 2 && z.m == 1, "");