[committed] c++: Add testcase for PR84494

[Patrick Palka via Gcc-patches]

We correctly accept this testcase ever since r10-5143.

gcc/testsuite/ChangeLog:

        PR c++/84494
        * g++.dg/cpp1y/constexpr-84494.C: New test.
---
 gcc/testsuite/g++.dg/cpp1y/constexpr-84494.C | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-84494.C

diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-84494.C 
b/gcc/testsuite/g++.dg/cpp1y/constexpr-84494.C
new file mode 100644
index 00000000000..762cfb4d396
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-84494.C
@@ -0,0 +1,11 @@
+// PR c++/84494
+// { dg-do compile { target c++14 } }
+
+struct X {
+  constexpr X() = default;
+  constexpr X(int x) : m_value(x) {}
+  constexpr X& operator=(const X &o) = default;
+  int m_value {};
+};
+
+static_assert((X() = X(10)).m_value == 10, "");
-- 
2.30.0.335.ge6362826a0