[clang-tidy] Add check: replace string::find(...) == 0 with absl::StartsWith

Patch by Niko Weh!

Reviewers: hokein

Subscribers: klimek, cfe-commits, ioeric, ilya-biryukov, ahedberg

Differential Revision: https://reviews.llvm.org/D43847

llvm-svn: 327111

1 files changed, 55 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/abseil-string-find-startswith.cpp b/clang-tools-extra/test/clang-tidy/abseil-string-find-startswith.cpp
new file mode 100644
index 00000000000..194e795be62
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/abseil-string-find-startswith.cpp
@@ -0,0 +1,55 @@
+// RUN: %check_clang_tidy %s abseil-string-find-startswith %t
+
+namespace std {
+template <typename T> class allocator {};
+template <typename T> class char_traits {};
+template <typename C, typename T = std::char_traits<C>,
+          typename A = std::allocator<C>>
+struct basic_string {
+  basic_string();
+  basic_string(const basic_string &);
+  basic_string(const C *, const A &a = A());
+  ~basic_string();
+  int find(basic_string<C> s, int pos = 0);
+  int find(const char *s, int pos = 0);
+};
+typedef basic_string<char> string;
+typedef basic_string<wchar_t> wstring;
+} // namespace std
+
+std::string foo(std::string);
+std::string bar();
+
+#define A_MACRO(x, y) ((x) == (y))
+
+void tests(std::string s) {
+  s.find("a") == 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use absl::StartsWith instead of find() == 0 [abseil-string-find-startswith]
+  // CHECK-FIXES: {{^[[:space:]]*}}absl::StartsWith(s, "a");{{$}}
+
+  s.find(s) == 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use absl::StartsWith
+  // CHECK-FIXES: {{^[[:space:]]*}}absl::StartsWith(s, s);{{$}}
+
+  s.find("aaa") != 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use !absl::StartsWith
+  // CHECK-FIXES: {{^[[:space:]]*}}!absl::StartsWith(s, "aaa");{{$}}
+
+  s.find(foo(foo(bar()))) != 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use !absl::StartsWith
+  // CHECK-FIXES: {{^[[:space:]]*}}!absl::StartsWith(s, foo(foo(bar())));{{$}}
+
+  if (s.find("....") == 0) { /* do something */ }
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use absl::StartsWith
+  // CHECK-FIXES: {{^[[:space:]]*}}if (absl::StartsWith(s, "....")) { /* do something */ }{{$}}
+
+  0 != s.find("a");
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use !absl::StartsWith
+  // CHECK-FIXES: {{^[[:space:]]*}}!absl::StartsWith(s, "a");{{$}}
+
+  // expressions that don't trigger the check are here.
+  A_MACRO(s.find("a"), 0);
+  s.find("a", 1) == 0;
+  s.find("a", 1) == 1;
+  s.find("a") == 1;
+}