third_party/llvm-project/clang-tools-extra/test/clang-tidy/modernize-use-transparent-functors.cpp

// RUN: %check_clang_tidy %s modernize-use-transparent-functors %t -- -- -std=c++14

namespace std {
template<class T>
struct remove_reference;

template <class T>
constexpr T &&forward(typename std::remove_reference<T>::type &t);

template <class T>
constexpr T &&forward(typename std::remove_reference<T>::type &&t);

template <typename T = void>
struct plus {
  constexpr T operator()(const T &Lhs, const T &Rhs) const;
};

template <>
struct plus<void> {
  template <typename T, typename U>
  constexpr auto operator()(T &&Lhs, U &&Rhs) const ->
    decltype(forward<T>(Lhs) + forward<U>(Rhs));
};

template <typename T = void>
struct less {
  constexpr bool operator()(const T &Lhs, const T &Rhs) const;
};

template <>
struct less<void> {
  template <typename T, typename U>
  constexpr bool operator()(T &&Lhs, U &&Rhs) const;
};

template <typename T = void>
struct logical_not {
  constexpr bool operator()(const T &Arg) const;
};

template <>
struct logical_not<void> {
  template <typename T>
  constexpr bool operator()(T &&Arg) const;
};

template <typename T>
class allocator;

template <
    class Key,
    class Compare = std::less<>,
    class Allocator = std::allocator<Key>>
class set {};

template <
    class Key,
    class Compare = std::less<Key>,
    class Allocator = std::allocator<Key>>
class set2 {};

template <class InputIt, class UnaryPredicate>
InputIt find_if(InputIt first, InputIt last,
                UnaryPredicate p);

template <class RandomIt, class Compare>
void sort(RandomIt first, RandomIt last, Compare comp);

class iterator {};
class string {};
}

int main() {
  using std::set;
  using std::less;
  std::set<int, std::less<int>> s;
  // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: prefer transparent functors 'less<>' [modernize-use-transparent-functors]
  // CHECK-FIXES: {{^}}  std::set<int, std::less<>> s;{{$}}
  set<int, std::less<int>> s2;
  // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: prefer transparent functors
  // CHECK-FIXES: {{^}}  set<int, std::less<>> s2;{{$}}
  set<int, less<int>> s3;
  // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: prefer transparent functors
  // CHECK-FIXES: {{^}}  set<int, less<>> s3;{{$}}
  std::set<int, std::less<>> s4;
  std::set<char *, std::less<std::string>> s5;
  std::set<set<int, less<int>>, std::less<>> s6;
  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: prefer transparent functors
  // CHECK-FIXES: {{^}}  std::set<set<int, less<>>, std::less<>> s6;{{$}}
  std::iterator begin, end;
  sort(begin, end, std::less<int>());
  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: prefer transparent functors
  std::sort(begin, end, std::less<>());
  find_if(begin, end, std::logical_not<bool>());
  // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: prefer transparent functors
  std::find_if(begin, end, std::logical_not<>());
  using my_set = std::set<int, std::less<int>>;
  // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: prefer transparent functors
  // CHECK-FIXES: {{^}}  using my_set = std::set<int, std::less<>>;{{$}}
  using my_set2 = std::set<char*, std::less<std::string>>;
  using my_less = std::less<std::string>;
  find_if(begin, end, my_less());
  // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: prefer transparent functors
  std::set2<int> control;
}