[clang-tidy/checks] Implement a clang-tidy check to verify Google Objective-C function naming conventions 📜

Summary:
§1 Description

This check finds function names in function declarations in Objective-C files that do not follow the naming pattern described in the Google Objective-C Style Guide. Function names should be in UpperCamelCase and functions that are not of static storage class should have an appropriate prefix as described in the Google Objective-C Style Guide. The function `main` is a notable exception. Function declarations in expansions in system headers are ignored.

Example conforming function definitions:
```
static bool IsPositive(int i) { return i > 0; }
static bool ABIsPositive(int i) { return i > 0; }
bool ABIsNegative(int i) { return i < 0; }
```

A fixit hint is generated for functions of static storage class but otherwise the check does not generate a fixit hint because an appropriate prefix for the function cannot be determined.

§2 Test Notes
* Verified clang-tidy tests pass successfully.
* Used check_clang_tidy.py to verify expected output of processing google-objc-function-naming.m

Reviewers: benhamilton, hokein, Wizard, aaron.ballman

Reviewed By: benhamilton

Subscribers: Eugene.Zelenko, mgorny, xazax.hun, cfe-commits

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D51575

llvm-svn: 347132

1 files changed, 52 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/google-objc-function-naming.m b/clang-tools-extra/test/clang-tidy/google-objc-function-naming.m
new file mode 100644
index 00000000000..8ca90f0f09d
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/google-objc-function-naming.m
@@ -0,0 +1,52 @@
+// RUN: %check_clang_tidy %s google-objc-function-naming %t
+
+typedef _Bool bool;
+
+static bool ispositive(int a) { return a > 0; }
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: function name 'ispositive' not using function naming conventions described by Google Objective-C style guide
+// CHECK-FIXES: static bool Ispositive(int a) { return a > 0; }
+
+static bool is_positive(int a) { return a > 0; }
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: function name 'is_positive' not using function naming conventions described by Google Objective-C style guide
+// CHECK-FIXES: static bool IsPositive(int a) { return a > 0; }
+
+static bool isPositive(int a) { return a > 0; }
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: function name 'isPositive' not using function naming conventions described by Google Objective-C style guide
+// CHECK-FIXES: static bool IsPositive(int a) { return a > 0; }
+
+static bool Is_Positive(int a) { return a > 0; }
+// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: function name 'Is_Positive' not using function naming conventions described by Google Objective-C style guide
+// CHECK-FIXES: static bool IsPositive(int a) { return a > 0; }
+
+static bool IsPositive(int a) { return a > 0; }
+
+bool ispalindrome(const char *str);
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function name 'ispalindrome' not using function naming conventions described by Google Objective-C style guide
+
+static const char *md5(const char *str) { return 0; }
+// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: function name 'md5' not using function naming conventions described by Google Objective-C style guide
+// CHECK-FIXES: static const char *Md5(const char *str) { return 0; }
+
+static const char *MD5(const char *str) { return 0; }
+
+static const char *URL(void) { return "https://clang.llvm.org/"; }
+
+static const char *DEFURL(void) { return "https://clang.llvm.org/"; }
+
+static const char *DEFFooURL(void) { return "https://clang.llvm.org/"; }
+
+static const char *StringFromNSString(id str) { return ""; }
+
+void ABLog_String(const char *str);
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function name 'ABLog_String' not using function naming conventions described by Google Objective-C style guide
+
+void ABLogString(const char *str);
+
+bool IsPrime(int a);
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function name 'IsPrime' not using function naming conventions described by Google Objective-C style guide
+
+const char *ABURL(void) { return "https://clang.llvm.org/"; }
+
+const char *ABFooURL(void) { return "https://clang.llvm.org/"; }
+
+int main(int argc, const char **argv) { return 0; }