--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class33.C	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,36 @@
+// PR c++/90938 - Initializing array with {1} works, but not {0}
+// { dg-do compile { target c++20 } }
+// { dg-options "-Wall" }
+
+struct A { int i; };
+struct B { A a[2]; };
+
+static const constexpr A a0 = { 0 };
+static const constexpr A a_ = { };
+
+template <B> struct X { };
+
+typedef X<B{ }>             XB;
+typedef X<B{{A{ }}}>        XB;
+typedef X<B{{A{ 0 }}}>      XB;
+typedef X<B{{a_}}>          XB;
+typedef X<B{{a0}}>          XB;
+typedef X<B{{a_, A{ }}}>    XB;
+typedef X<B{{a_, A{ 0 }}}>  XB;
+typedef X<B{{a_, a_}}>      XB;
+typedef X<B{{a_, a0}}>      XB;
+
+
+struct C { constexpr C () = default; };
+struct D { C c[2]; };
+
+static const constexpr C c_ = { };
+
+template <D> struct Y { };
+
+typedef Y<D{ }>             YD;
+typedef Y<D{C { }}>         YD;
+typedef Y<D{{c_}}>          YD;
+typedef Y<D{C{ }, C{ }}>    YD;
+typedef Y<D{C{ }, c_}>      YD;
+typedef Y<D{{c_, c_}}>      YD;