c++: Add testcase for already fixed PR [PR103807]

We accept this testcase since r13-806-g221acd67ca50f8.

	PR c++/103807

gcc/testsuite/ChangeLog:

	* g++.dg/cpp2a/lambda-targ1.C: New test.

diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-targ1.C b/gcc/testsuite/g++.dg/cpp2a/lambda-targ1.C
new file mode 100644 (file)
index 0000000..07fa6f9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-targ1.C
@@ -0,0 +1,11 @@
+// PR c++/103807
+// { dg-do compile { target c++20 } }
+
+template<auto = +[]{}>
+struct A { };
+
+A x;
+
+int main() {
+  A y;
+}