llvm-capstone/clang/test/SemaTemplate/concepts-lambda.cpp

// RUN: %clang_cc1 -std=c++20 -verify %s
// expected-no-diagnostics

namespace GH57945 {
  template<typename T>
    concept c = true;

  template<typename>
    auto f = []() requires c<void> {
    };

  void g() {
      f<int>();
  };
}

namespace GH57945_2 {
  template<typename>
    concept c = true;

  template<typename T>
    auto f = [](auto... args) requires c<T>  {
    };

  template <typename T>
  auto f2 = [](auto... args)
    requires (sizeof...(args) > 0)
  {};

  void g() {
      f<void>();
      f2<void>(5.0);
  }
}

namespace GH57958 {
  template<class> concept C = true;
  template<int> constexpr bool v = [](C auto) { return true; }(0);
  int _ = v<0>;
}
namespace GH57958_2 {
  template<class> concept C = true;
  template<int> constexpr bool v = [](C auto...) { return true; }(0);
  int _ = v<0>;
}

namespace GH57971 {
  template<typename>
    concept any = true;

  template<typename>
    auto f = [](any auto) {
    };

  using function_ptr = void(*)(int);
  function_ptr ptr = f<void>;
}

// GH58368: A lambda defined in a concept requires we store
// the concept as a part of the lambda context.
namespace LambdaInConcept {
using size_t = unsigned long;

template<size_t...Ts>
struct IdxSeq{};

template <class T, class... Ts>
concept NotLike = true;

template <size_t, class... Ts>
struct AnyExcept {
  template <NotLike<Ts...> T> operator T&() const;
  template <NotLike<Ts...> T> operator T&&() const;
};

template <class T>
  concept ConstructibleWithN = (requires {
                                []<size_t I, size_t... Idxs>
                                (IdxSeq<I, Idxs...>)
                                requires requires { T{AnyExcept<I, T>{}}; }
                                { }
                                (IdxSeq<1,2,3>{});
    });

struct Foo {
  int i;
  double j;
  char k;
};

static_assert(ConstructibleWithN<Foo>);

}