xref: /llvm-project/clang/test/SemaCXX/lambda-expressions-gh56071.cpp (revision d6ae4bd686714d34969012fa273140e547606d81)
1*d6ae4bd6SCorentin Jabot // RUN: %clang_cc1 -fsyntax-only -verify %s -Wno-unused-value -std=c++17
2*d6ae4bd6SCorentin Jabot // expected-no-diagnostics
3*d6ae4bd6SCorentin Jabot namespace test1 {
4*d6ae4bd6SCorentin Jabot 
return_num()5*d6ae4bd6SCorentin Jabot template <int num> int return_num() { return num; }
6*d6ae4bd6SCorentin Jabot 
7*d6ae4bd6SCorentin Jabot template <typename lambda> struct lambda_wrapper {
8*d6ae4bd6SCorentin Jabot   lambda &outer_lambda;
lambda_wrappertest1::lambda_wrapper9*d6ae4bd6SCorentin Jabot   lambda_wrapper(lambda& outer_lambda) : outer_lambda(outer_lambda) {}
operator +test1::lambda_wrapper10*d6ae4bd6SCorentin Jabot   template <typename T> auto operator+(T t) { outer_lambda(t); return 1; }
11*d6ae4bd6SCorentin Jabot };
12*d6ae4bd6SCorentin Jabot 
13*d6ae4bd6SCorentin Jabot template <int... nums, typename lambda>
bw(lambda & outer_lambda)14*d6ae4bd6SCorentin Jabot void bw(lambda& outer_lambda) {
15*d6ae4bd6SCorentin Jabot   (lambda_wrapper(outer_lambda) + ... + return_num<nums>());
16*d6ae4bd6SCorentin Jabot }
17*d6ae4bd6SCorentin Jabot 
check_return_type(lambda inner_lambda)18*d6ae4bd6SCorentin Jabot template <typename lambda> auto check_return_type(lambda inner_lambda) {
19*d6ae4bd6SCorentin Jabot   using inner_lambda_return_type = decltype(inner_lambda(5));
20*d6ae4bd6SCorentin Jabot }
21*d6ae4bd6SCorentin Jabot 
cs()22*d6ae4bd6SCorentin Jabot void cs() {
23*d6ae4bd6SCorentin Jabot   auto outer_lambda = [](auto param) {
24*d6ae4bd6SCorentin Jabot     auto inner_lambda = [](auto o) -> decltype(param) {};
25*d6ae4bd6SCorentin Jabot     check_return_type(inner_lambda);
26*d6ae4bd6SCorentin Jabot   };
27*d6ae4bd6SCorentin Jabot   bw<1,2>(outer_lambda);
28*d6ae4bd6SCorentin Jabot }
29*d6ae4bd6SCorentin Jabot 
30*d6ae4bd6SCorentin Jabot }  // namespace test1
31*d6ae4bd6SCorentin Jabot 
32*d6ae4bd6SCorentin Jabot namespace test2 {
33*d6ae4bd6SCorentin Jabot 
34*d6ae4bd6SCorentin Jabot template <typename lambda>
run_lambda_with_zero(lambda l)35*d6ae4bd6SCorentin Jabot auto run_lambda_with_zero(lambda l) {
36*d6ae4bd6SCorentin Jabot   l(0);
37*d6ae4bd6SCorentin Jabot }
38*d6ae4bd6SCorentin Jabot template <typename ... Ts, typename lambda>
run_lambda_once_per_type(lambda l)39*d6ae4bd6SCorentin Jabot void run_lambda_once_per_type(lambda l) {
40*d6ae4bd6SCorentin Jabot   ((Ts{}, run_lambda_with_zero(l)), ...);
41*d6ae4bd6SCorentin Jabot }
inner_function()42*d6ae4bd6SCorentin Jabot template <typename> void inner_function() {
43*d6ae4bd6SCorentin Jabot   char c;
44*d6ae4bd6SCorentin Jabot   [](auto param) -> decltype(c) { return param; }(0);
45*d6ae4bd6SCorentin Jabot }
run()46*d6ae4bd6SCorentin Jabot void run() {
47*d6ae4bd6SCorentin Jabot   auto x = [](auto) -> void { inner_function<int>(); };
48*d6ae4bd6SCorentin Jabot   run_lambda_once_per_type<int>(x);
49*d6ae4bd6SCorentin Jabot }
50*d6ae4bd6SCorentin Jabot 
51*d6ae4bd6SCorentin Jabot }  // namespace test2
52