--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda1.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,33 @@
+// PR c++/82565
+// { dg-do compile { target c++2a } }
+
+struct string
+{
+  string();
+  string(const char *);
+  bool empty() const;
+};
+
+template<class From, class To>
+concept convertible_to = requires(From (&f)(), void (&g)(To)) { g(f()); };
+
+template<typename T, typename ReturnType>
+concept Concept =
+  requires(T t, const string& s) {
+    { t(s) } -> convertible_to<ReturnType>;
+  };
+
+struct test {
+  string _str;
+
+  template<typename Visitor>
+    requires Concept<Visitor, bool>
+  decltype(auto) visit(Visitor&& visitor) const {
+    return visitor(_str);
+  }
+
+};
+
+int main() {
+  test().visit([] (auto& x) { return x.empty(); });
+}