--- /dev/null
+// P1401R5: Narrowing contextual conversions to bool
+// { dg-do compile { target c++11 } }
+
+void f() noexcept(sizeof(char[2])); // { dg-error "narrowing" } conversion of value 2 to type bool
+void g() noexcept(sizeof(char)); // OK, conversion of value 1 to type bool is non-narrowing
+
+#if __cpp_conditional_explicit
+struct S {
+ explicit(sizeof(char[2])) S(char); // { dg-error "narrowing" "" { target c++20 } }
+ explicit(sizeof(char)) S(bool); // OK, conversion of value 1 to type bool is non-narrowing
+};
+#endif
+
+static_assert(sizeof(int[2]), ""); // OK, narrowing allowed
+
+#if __cpp_if_constexpr
+int main()
+{
+ if constexpr (sizeof(int[2])) // OK, narrowing allowed
+ {}
+}
+#endif