[clang-tidy ObjC] [3/3] New check objc-forbidden-subclassing

Summary:
This is part 3 of 3 of a series of changes to improve Objective-C
linting in clang-tidy.

This adds a new clang-tidy check `objc-forbidden-subclassing` which
ensures clients do not create subclasses of Objective-C classes which
are not designed to be subclassed.

(Note that for code under your control, you should use
__attribute__((objc_subclassing_restricted)) instead -- this
is intended for third-party APIs which cannot be modified.)

By default, the following classes (which are publicly documented
as not supporting subclassing) are forbidden from subclassing:

ABNewPersonViewController
ABPeoplePickerNavigationController
ABPersonViewController
ABUnknownPersonViewController
NSHashTable
NSMapTable
NSPointerArray
NSPointerFunctions
NSTimer
UIActionSheet
UIAlertView
UIImagePickerController
UITextInputMode
UIWebView

Clients can set a CheckOption
`objc-forbidden-subclassing.ClassNames` to a semicolon-separated
list of class names, which overrides this list.

Test Plan: `ninja check-clang-tools`

Patch by Ben Hamilton!

Reviewers: hokein, alexfh

Reviewed By: hokein

Subscribers: saidinwot, Wizard, srhines, mgorny, xazax.hun

Differential Revision: https://reviews.llvm.org/D39142

llvm-svn: 316744

1 files changed, 29 insertions, 1 deletions

diff --git a/clang-tools-extra/unittests/clang-tidy/ObjCModuleTest.cpp b/clang-tools-extra/unittests/clang-tidy/ObjCModuleTest.cpp
index c50480a65fc..92ae8e1038f 100644
--- a/clang-tools-extra/unittests/clang-tidy/ObjCModuleTest.cpp
+++ b/clang-tools-extra/unittests/clang-tidy/ObjCModuleTest.cpp
@@ -9,12 +9,40 @@
 
 #include "ClangTidyTest.h"
 #include "gtest/gtest.h"
+#include "objc/ForbiddenSubclassingCheck.h"
+
+using namespace clang::tidy::objc;
 
 namespace clang {
 namespace tidy {
 namespace test {
 
-// TODO(D39142) Add unit tests for the ObjC module here once a check lands.
+TEST(ObjCForbiddenSubclassing, AllowedSubclass) {
+  std::vector<ClangTidyError> Errors;
+  runCheckOnCode<ForbiddenSubclassingCheck>(
+      "@interface Foo\n"
+      "@end\n"
+      "@interface Bar : Foo\n"
+      "@end\n",
+      &Errors,
+      "input.m");
+  EXPECT_EQ(0ul, Errors.size());
+}
+
+TEST(ObjCForbiddenSubclassing, ForbiddenSubclass) {
+  std::vector<ClangTidyError> Errors;
+  runCheckOnCode<ForbiddenSubclassingCheck>(
+      "@interface UIImagePickerController\n"
+      "@end\n"
+      "@interface Foo : UIImagePickerController\n"
+      "@end\n",
+      &Errors,
+      "input.m");
+  EXPECT_EQ(1ul, Errors.size());
+  EXPECT_EQ(
+      "Objective-C interface 'Foo' subclasses 'UIImagePickerController', which is not intended to be subclassed",
+      Errors[0].Message.Message);
+}
 
 } // namespace test
 } // namespace tidy