1 files changed, 188 insertions, 0 deletions
diff --git a/clang-tools-extra/test/clang-tidy/abseil-redundant-strcat-calls.cpp b/clang-tools-extra/test/clang-tidy/abseil-redundant-strcat-calls.cpp
new file mode 100644
index 00000000000..2d723797143
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/abseil-redundant-strcat-calls.cpp
@@ -0,0 +1,188 @@
+// RUN: %check_clang_tidy %s abseil-redundant-strcat-calls %t
+
+int strlen(const char *);
+
+// Here we mimic the hierarchy of ::string.
+// We need to do so because we are matching on the fully qualified name of the
+// methods.
+struct __sso_string_base {};
+namespace __gnu_cxx {
+template <typename A, typename B, typename C, typename D = __sso_string_base>
+class __versa_string {
+ public:
+  const char *c_str() const;
+  const char *data() const;
+  int size() const;
+  int capacity() const;
+  int length() const;
+  bool empty() const;
+  char &operator[](int);
+  void clear();
+  void resize(int);
+  int compare(const __versa_string &) const;
+};
+}  // namespace __gnu_cxx
+
+namespace std {
+template <typename T>
+class char_traits {};
+template <typename T>
+class allocator {};
+}  // namespace std
+
+template <typename A, typename B = std::char_traits<A>,
+          typename C = std::allocator<A>>
+class basic_string : public __gnu_cxx::__versa_string<A, B, C> {
+ public:
+  basic_string();
+  basic_string(const basic_string &);
+  basic_string(const char *, C = C());
+  basic_string(const char *, int, C = C());
+  basic_string(const basic_string &, int, int, C = C());
+  ~basic_string();
+
+  basic_string &operator+=(const basic_string &);
+};
+
+template <typename A, typename B, typename C>
+basic_string<A, B, C> operator+(const basic_string<A, B, C> &,
+                                const basic_string<A, B, C> &);
+template <typename A, typename B, typename C>
+basic_string<A, B, C> operator+(const basic_string<A, B, C> &, const char *);
+
+typedef basic_string<char> string;
+
+bool operator==(const string &, const string &);
+bool operator==(const string &, const char *);
+bool operator==(const char *, const string &);
+
+bool operator!=(const string &, const string &);
+bool operator<(const string &, const string &);
+bool operator>(const string &, const string &);
+bool operator<=(const string &, const string &);
+bool operator>=(const string &, const string &);
+
+namespace std {
+template <typename _CharT, typename _Traits = char_traits<_CharT>,
+          typename _Alloc = allocator<_CharT>>
+class basic_string;
+
+template <typename _CharT, typename _Traits, typename _Alloc>
+class basic_string {
+ public:
+  basic_string();
+  basic_string(const basic_string &);
+  basic_string(const char *, const _Alloc & = _Alloc());
+  basic_string(const char *, int, const _Alloc & = _Alloc());
+  basic_string(const basic_string &, int, int, const _Alloc & = _Alloc());
+  ~basic_string();
+
+  basic_string &operator+=(const basic_string &);
+
+  unsigned size() const;
+  unsigned length() const;
+  bool empty() const;
+};
+
+typedef basic_string<char> string;
+}  // namespace std
+
+namespace absl {
+
+class string_view {
+ public:
+  typedef std::char_traits<char> traits_type;
+
+  string_view();
+  string_view(const char *);
+  string_view(const string &);
+  string_view(const char *, int);
+  string_view(string_view, int);
+
+  template <typename A>
+  explicit operator ::basic_string<char, traits_type, A>() const;
+
+  const char *data() const;
+  int size() const;
+  int length() const;
+};
+
+bool operator==(string_view A, string_view B);
+
+struct AlphaNum {
+  AlphaNum(int i);
+  AlphaNum(double f);
+  AlphaNum(const char *c_str);
+  AlphaNum(const string &str);
+  AlphaNum(const string_view &pc);
+
+ private:
+  AlphaNum(const AlphaNum &);
+  AlphaNum &operator=(const AlphaNum &);
+};
+
+string StrCat(const AlphaNum &A);
+string StrCat(const AlphaNum &A, const AlphaNum &B);
+string StrCat(const AlphaNum &A, const AlphaNum &B, const AlphaNum &C);
+string StrCat(const AlphaNum &A, const AlphaNum &B, const AlphaNum &C,
+              const AlphaNum &D);
+
+// Support 5 or more arguments
+template <typename... AV>
+string StrCat(const AlphaNum &A, const AlphaNum &B, const AlphaNum &C,
+              const AlphaNum &D, const AlphaNum &E, const AV &... args);
+
+void StrAppend(string *Dest, const AlphaNum &A);
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B);
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B,
+               const AlphaNum &C);
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B,
+               const AlphaNum &C, const AlphaNum &D);
+
+// Support 5 or more arguments
+template <typename... AV>
+void StrAppend(string *Dest, const AlphaNum &A, const AlphaNum &B,
+               const AlphaNum &C, const AlphaNum &D, const AlphaNum &E,
+               const AV &... args);
+
+}  // namespace absl
+
+using absl::AlphaNum;
+using absl::StrAppend;
+using absl::StrCat;
+
+void Positives() {
+  string S = StrCat(1, StrCat("A", StrCat(1.1)));
+  // CHECK-MESSAGES: [[@LINE-1]]:14: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+  S = StrCat(StrCat(StrCat(StrCat(StrCat(1)))));
+  // CHECK-MESSAGES: [[@LINE-1]]:7: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+  // TODO: should trigger. The issue here is that in the current
+  // implementation we ignore any StrCat with StrCat ancestors. Therefore
+  // inserting anything in between calls will disable triggering the deepest
+  // ones.
+  // s = StrCat(Identity(StrCat(StrCat(1, 2), StrCat(3, 4))));
+
+  StrAppend(&S, 001, StrCat(1, 2, "3"), StrCat("FOO"));
+  // CHECK-MESSAGES: [[@LINE-1]]:3: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+  StrAppend(&S, 001, StrCat(StrCat(1, 2), "3"), StrCat("FOO"));
+  // CHECK-MESSAGES: [[@LINE-1]]:3: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+
+  // Too many args. Ignore for now.
+  S = StrCat(1, 2, StrCat(3, 4, 5, 6, 7), 8, 9, 10,
+             StrCat(11, 12, 13, 14, 15, 16, 17, 18), 19, 20, 21, 22, 23, 24, 25,
+             26, 27);
+  // CHECK-MESSAGES: :[[@LINE-3]]:7: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+  StrAppend(&S, StrCat(1, 2, 3, 4, 5), StrCat(6, 7, 8, 9, 10));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: multiple calls to 'absl::StrCat' can be flattened into a single call
+}
+
+void Negatives() {
+  // One arg. It is used for conversion. Ignore.
+  string S = StrCat(1);
+
+#define A_MACRO(x, y, z) StrCat(x, y, z)
+  S = A_MACRO(1, 2, StrCat("A", "B"));
+}