--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-uneval3.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,12 @@
+// { dg-do compile { target c++2a } }
+
+template <int N> void foo(const char (*s)[([]{}, N)]) {}
+template <class T> void spam(decltype([]{}) (*s)[sizeof(T)]) {}
+
+int main()
+{
+  foo<1>(nullptr);
+  spam<char>(nullptr);
+}
+
+// { dg-final { scan-assembler-not "weak.*_Z" } }