[clang-tidy] Disable google-runtime-int in Objective-C++ 🔓

Summary:
In contrast to Google C++, Objective-C often uses built-in integer types
other than `int`. In fact, the Objective-C runtime itself defines the
types NSInteger¹ and NSUInteger² which are variant types depending on
the target architecture. The Objective-C style guide indicates that
usage of system types with variant sizes is appropriate when handling
values provided by system interfaces³. Objective-C++ is commonly the
result of conversion from Objective-C to Objective-C++ for the purpose
of integrating C++ functionality. The opposite of Objective-C++ being
used to expose Objective-C functionality to C++ is less common,
potentially because Objective-C has a signficantly more uneven presence
on different platforms compared to C++. This generally predisposes
Objective-C++ to commonly being more Objective-C than C++. Forcing
Objective-C++ developers to perform conversions between variant system types
and fixed size integer types depending on target architecture when
Objective-C++ commonly uses variant system types from Objective-C is
likely to lead to more bugs and overhead than benefit. For that reason,
this change proposes to disable google-runtime-int in Objective-C++.

[1] https://developer.apple.com/documentation/objectivec/nsinteger?language=objc
[2] https://developer.apple.com/documentation/objectivec/nsuinteger?language=objc
[3] "Types long, NSInteger, NSUInteger, and CGFloat vary in size between
32- and 64-bit builds. Use of these types is appropriate when handling
values exposed by system interfaces, but they should be avoided for most
other computations."
https://github.com/google/styleguide/blob/gh-pages/objcguide.md#types-with-inconsistent-sizes

Subscribers: xazax.hun, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D59336

llvm-svn: 356627

clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp

@@ -54,7 +54,9 @@ void IntegerTypesCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
 
 void IntegerTypesCheck::registerMatchers(MatchFinder *Finder) {
   // Find all TypeLocs. The relevant Style Guide rule only applies to C++.
-  if (!getLangOpts().CPlusPlus)
+  // This check is also not applied in Objective-C++ sources as Objective-C
+  // often uses built-in integer types other than `int`.
+  if (!getLangOpts().CPlusPlus || getLangOpts().ObjC)
     return;
   // Match any integer types, unless they are passed to a printf-based API:
   //

clang-tools-extra/docs/ReleaseNotes.rst

@@ -115,6 +115,9 @@ Improvements to clang-tidy
   `CommentUserDefiniedLiterals`, `CommentStringLiterals`,
   `CommentCharacterLiterals` & `CommentNullPtrs` options.
 
+- The :doc:`google-runtime-int <clang-tidy/checks/google-runtime-int>`
+  check has been disabled in Objective-C++.
+
 - The `Acronyms` and `IncludeDefaultAcronyms` options for the
   :doc:`objc-property-declaration <clang-tidy/checks/objc-property-declaration>`
   check have been removed.

clang-tools-extra/test/clang-tidy/google-runtime-int.m

@@ -0,0 +1,32 @@
+// RUN: clang-tidy -checks=-*,google-runtime-int %s 2>&1 -- | count 0
+// RUN: clang-tidy -checks=-*,google-runtime-int %s 2>&1 -- -x objective-c++ | count 0
+
+typedef long NSInteger;
+typedef unsigned long NSUInteger;
+
+@interface NSString
+@property(readonly) NSInteger integerValue;
+@property(readonly) long long longLongValue;
+@property(readonly) NSUInteger length;
+@end
+
+NSInteger Foo(NSString *s) {
+  return [s integerValue];
+}
+
+long long Bar(NSString *s) {
+  return [s longLongValue];
+}
+
+NSUInteger Baz(NSString *s) {
+  return [s length];
+}
+
+unsigned short NSSwapShort(unsigned short inv);
+
+long DoSomeMath(long a, short b) {
+  short c = NSSwapShort(b);
+  long a2 = a * 5L;
+  return a2 + c;
+}
+