[PATCH] D46659: [clang-tidy/google-readability-casting] Allow C-style casts to/from Objective-C object types

[Ben Hamilton via Phabricator via cfe-commits]

benhamilton created this revision.
benhamilton added reviewers: alexfh, Wizard, hokein.
Herald added a subscriber: cfe-commits.

Previously, `google-readability-casting` would trigger for
Objective-C++ code using C-style casts to or from Objective-C object
types.

The official Google Objective-C standard says Objective-C++ allows
authors to mix the Objective-C style (which uses C-style casts) and
C++ (which disallows it):

http://google.github.io/styleguide/objcguide.html#style-matches-the-language

So, to resolve this conflict, this diff updates
`google-readability-casting` to ignore C-style casts to or from
Objective-C object types.

Test Plan: New tests added. Ran tests with:

  % make -j16 check-clang-tools
  Before diff, confirmed tests failed:
  https://reviews.llvm.org/P8081
  After diff, confirrmed tests passed.


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D46659

Files:
  clang-tidy/google/AvoidCStyleCastsCheck.cpp
  test/clang-tidy/google-readability-casting.mm


Index: test/clang-tidy/google-readability-casting.mm
===================================================================
--- /dev/null
+++ test/clang-tidy/google-readability-casting.mm
@@ -0,0 +1,42 @@
+// RUN: clang-tidy %s -checks=-*,google-readability-casting -- \
+// RUN:   -xobjective-c++ -fobjc-abi-version=2 -fobjc-arc | count 0
+
+// Note: this test expects no diagnostics, but FileCheck cannot handle that,
+// hence the use of | count 0.
+
+#define nil 0
+
+ at interface Foo
+ at end
+
+ at protocol Proto
+ at end
+
+ at interface Bar : Foo <Proto>
+ at end
+
+ at interface Baz : Foo <Proto>
+ at end
+
+void foo() {
+  id nilObj = nil;
+  Foo *foo = (Foo *)nilObj;
+  Bar *bar = (Bar *)nilObj;
+  id ego = (id)foo;
+  foo = (Foo *)bar;
+  foo = (id)bar;
+  id<Proto> nilProto = (id<Proto>)bar;
+  ego = (id)nilProto;
+  bar = (Bar *)nilProto;
+  Foo<Proto> *fooProto = (Foo<Proto> *)bar;
+  Baz *baz = (Baz *)bar;
+  Class klass = (Class)nilObj;
+  ego = (id)klass;
+  void *voidStar = nullptr;
+  foo = (__bridge Foo *)voidStar;
+  nilProto = (__bridge id<Proto>)voidStar;
+  klass = (__bridge Class)voidStar;
+  voidStar = (__bridge void *)foo;
+  voidStar = (__bridge void *)nilProto;
+  voidStar = (__bridge void *)klass;
+}
Index: clang-tidy/google/AvoidCStyleCastsCheck.cpp
===================================================================
--- clang-tidy/google/AvoidCStyleCastsCheck.cpp
+++ clang-tidy/google/AvoidCStyleCastsCheck.cpp
@@ -110,6 +110,10 @@
   // compiled as C++.
   if (getCurrentMainFile().endswith(".c"))
     return;
+  // Ignore casts between Objective-C types.
+  if (SourceType->isObjCObjectPointerType() ||
+      DestType->isObjCObjectPointerType())
+    return;
 
   SourceManager &SM = *Result.SourceManager;
 


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