--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/explicit4.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,41 @@
+// P0892R2
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+template<int T = 1>
+struct S {
+  explicit(T) S(int);
+  explicit(!T) S(int, int);
+};
+
+template<typename T, int N>
+struct S2 {
+  explicit(N) S2(T);
+};
+
+template<typename T>
+struct S3 {
+  explicit((T) 1.0) S3(int);
+};
+
+int
+main ()
+{
+  S<> s1 = { 1 }; // { dg-error "converting" }
+  S<true> s2 = { 1 }; // { dg-error "converting" }
+  S<false> s3 = { 1 };
+  S<> s4{ 1 };
+  S<true> s5{ 1 };
+  S<> s6 = { 1, 2 };
+  S<true> s7 = { 1, 2 };
+  S<false> s8 = { 1, 2 }; // { dg-error "converting" }
+  S<false> s9{ 1, 2 };
+
+  const int x = 1;
+  S<x> s10 = { 1 }; // { dg-error "converting" }
+  S<x> s11{ 2 };
+
+  S2<int, true> s12 = { 1 }; // { dg-error "converting" }
+
+  S3<int> s13 = { 1 }; // { dg-error "converting" }
+}