clang/test/SemaCXX/lambda-expressions-gh56071.cpp

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