--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic1.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,40 @@
+// PR c++/88337 - Implement P1327R1: Allow dynamic_cast/typeid in constexpr.
+// { dg-do compile { target c++2a } }
+
+// Downcast.
+
+struct B {
+  virtual void baz () {}
+};
+ 
+struct D : B { };
+
+constexpr bool
+fn ()
+{
+  bool ok = true;
+  B b;
+  B *b1 = &b;
+  if (D *pd = dynamic_cast<D*>(b1))
+    ok = false;
+
+  D d;
+  B *b2 = &d;
+  if (D *pd = dynamic_cast<D*>(b2))
+    /*OK*/;
+  else
+   ok = false;
+    
+  return ok;
+}
+
+static_assert(fn ());
+
+constexpr D d;
+constexpr B b;
+constexpr B *b1 = const_cast<B*>(&b);
+constexpr B *b2 = const_cast<D*>(&d);
+static_assert(dynamic_cast<D*>(b2) == &d);
+static_assert(&dynamic_cast<D&>(*b2) == &d);
+static_assert(dynamic_cast<const B*>(&d) == &d);
+static_assert(&dynamic_cast<const B&>(d) == &d);