llvm-project/clang-tools-extra/test/clang-tidy/checkers/readability-container-contains.cpp

// RUN: %check_clang_tidy -std=c++20 %s readability-container-contains %t

// Some *very* simplified versions of `map` etc.
namespace std {

template <class Key, class T>
struct map {
  unsigned count(const Key &K) const;
  bool contains(const Key &K) const;
  void *find(const Key &K);
  void *end();
};

template <class Key>
struct set {
  unsigned count(const Key &K) const;
  bool contains(const Key &K) const;
};

template <class Key>
struct unordered_set {
  unsigned count(const Key &K) const;
  bool contains(const Key &K) const;
};

template <class Key, class T>
struct multimap {
  unsigned count(const Key &K) const;
  bool contains(const Key &K) const;
};

} // namespace std

// Check that we detect various common ways to check for membership
int testDifferentCheckTypes(std::map<int, int> &MyMap) {
  if (MyMap.count(0))
    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use 'contains' to check for membership [readability-container-contains]
    // CHECK-FIXES: if (MyMap.contains(0))
    return 1;
  bool C1 = MyMap.count(1);
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C1 = MyMap.contains(1);
  auto C2 = static_cast<bool>(MyMap.count(1));
  // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C2 = static_cast<bool>(MyMap.contains(1));
  auto C3 = MyMap.count(2) != 0;
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C3 = MyMap.contains(2);
  auto C4 = MyMap.count(3) > 0;
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C4 = MyMap.contains(3);
  auto C5 = MyMap.count(4) >= 1;
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C5 = MyMap.contains(4);
  auto C6 = MyMap.find(5) != MyMap.end();
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C6 = MyMap.contains(5);
  return C1 + C2 + C3 + C4 + C5 + C6;
}

// Check that we detect various common ways to check for non-membership
int testNegativeChecks(std::map<int, int> &MyMap) {
  bool C1 = !MyMap.count(-1);
  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C1 = !MyMap.contains(-1);
  auto C2 = MyMap.count(-2) == 0;
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C2 = !MyMap.contains(-2);
  auto C3 = MyMap.count(-3) <= 0;
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C3 = !MyMap.contains(-3);
  auto C4 = MyMap.count(-4) < 1;
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C4 = !MyMap.contains(-4);
  auto C5 = MyMap.find(-5) == MyMap.end();
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: auto C5 = !MyMap.contains(-5);
  return C1 + C2 + C3 + C4 + C5;
}

// Check for various types
int testDifferentTypes(std::map<int, int> &M, std::unordered_set<int> &US, std::set<int> &S, std::multimap<int, int> &MM) {
  bool C1 = M.count(1001);
  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C1 = M.contains(1001);
  bool C2 = US.count(1002);
  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C2 = US.contains(1002);
  bool C3 = S.count(1003);
  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C3 = S.contains(1003);
  bool C4 = MM.count(1004);
  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C4 = MM.contains(1004);
  return C1 + C2 + C3 + C4;
}

// The check detects all kind of `const`, reference, rvalue-reference and value types.
int testQualifiedTypes(std::map<int, int> ValueM, std::map<int, int> &RefM, const std::map<int, int> &ConstRefM, std::map<int, int> &&RValueM) {
  bool C1 = ValueM.count(2001);
  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C1 = ValueM.contains(2001);
  bool C2 = RefM.count(2002);
  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C2 = RefM.contains(2002);
  bool C3 = ConstRefM.count(2003);
  // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C3 = ConstRefM.contains(2003);
  bool C4 = RValueM.count(2004);
  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C4 = RValueM.contains(2004);
  return C1 + C2 + C3 + C4;
}

// This is effectively a membership check, as the result is implicitly casted
// to `bool`.
bool returnContains(std::map<int, int> &M) {
  return M.count(42);
  // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: return M.contains(42);
}

// This returns the actual count and should not be rewritten
int actualCount(std::multimap<int, int> &M) {
  return M.count(21);
  // NO-WARNING.
  // CHECK-FIXES: return M.count(21);
}

// Check that we are not confused by aliases
namespace s2 = std;
using MyMapT = s2::map<int, int>;
int typeAliases(MyMapT &MyMap) {
  bool C1 = MyMap.count(99);
  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: bool C1 = MyMap.contains(99);
  return C1;
}

// Check that the tests also trigger for a local variable and not only for
// function arguments.
bool localVar() {
  using namespace std;
  map<int, int> LocalM;
  return LocalM.count(42);
  // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use 'contains' to check for membership [readability-container-contains]
  // CHECK-FIXES: return LocalM.contains(42);
}

// Check various usages of an actual `count` which isn't rewritten
int nonRewrittenCount(std::multimap<int, int> &MyMap) {
  // This is an actual test if we have at least 2 usages. Shouldn't be rewritten.
  bool C1 = MyMap.count(1) >= 2;
  // NO-WARNING.
  // CHECK-FIXES: bool C1 = MyMap.count(1) >= 2;

  // "< 0" makes little sense and is always `false`. Still, let's ensure we
  // don't accidentally rewrite it to 'contains'.
  bool C2 = MyMap.count(2) < 0;
  // NO-WARNING.
  // CHECK-FIXES: bool C2 = MyMap.count(2) < 0;

  // The `count` is used in some more complicated formula.
  bool C3 = MyMap.count(1) + MyMap.count(2) * 2 + MyMap.count(3) / 3 >= 20;
  // NO-WARNING.
  // CHECK-FIXES: bool C3 = MyMap.count(1) + MyMap.count(2) * 2 + MyMap.count(3) / 3 >= 20;

  // This could theoretically be rewritten into a 'contains' after removig the
  // `4` on both sides of the comparison. For the time being, we don't detect
  // this case.
  bool C4 = MyMap.count(1) + 4 > 4;
  // NO-WARNING.
  // CHECK-FIXES: bool C4 = MyMap.count(1) + 4 > 4;

  return C1 + C2 + C3 + C4;
}

// We don't want to rewrite if the `contains` call is from a macro expansion
int testMacroExpansion(std::unordered_set<int> &MySet) {
#define COUNT_ONES(SET) SET.count(1)
  // Rewriting the macro would break the code
  // CHECK-FIXES: #define COUNT_ONES(SET) SET.count(1)
  // We still want to warn the user even if we don't offer a fixit
  if (COUNT_ONES(MySet)) {
    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use 'contains' to check for membership [readability-container-contains]
    // CHECK-MESSAGES: note: expanded from macro 'COUNT_ONES'
    return COUNT_ONES(MySet);
  }
#undef COUNT_ONES
#define COUNT_ONES count(1)
  // Rewriting the macro would break the code
  // CHECK-FIXES: #define COUNT_ONES count(1)
  // We still want to warn the user even if we don't offer a fixit
  if (MySet.COUNT_ONES) {
    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: use 'contains' to check for membership [readability-container-contains]
    // CHECK-MESSAGES: note: expanded from macro 'COUNT_ONES'
    return MySet.COUNT_ONES;
  }
#undef COUNT_ONES
#define MY_SET MySet
  // CHECK-FIXES: #define MY_SET MySet
  // We still want to rewrite one of the two calls to `count`
  if (MY_SET.count(1)) {
    // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: use 'contains' to check for membership [readability-container-contains]
    // CHECK-FIXES: if (MY_SET.contains(1)) {
    return MY_SET.count(1);
  }
#undef MY_SET
  return 0;
}

// The following map has the same interface like `std::map`.
template <class Key, class T>
struct CustomMap {
  unsigned count(const Key &K) const;
  bool contains(const Key &K) const;
  void *find(const Key &K);
  void *end();
};

// The clang-tidy check is currently hard-coded against the `std::` containers
// and hence won't annotate the following instance. We might change this in the
// future and also detect the following case.
void *testDifferentCheckTypes(CustomMap<int, int> &MyMap) {
  if (MyMap.count(0))
    // NO-WARNING.
    // CHECK-FIXES: if (MyMap.count(0))
    return nullptr;
  return MyMap.find(2);
}