2f6a52816f
Summary: Apple documentation states that: "If two objects are equal, they must have the same hash value. This last point is particularly important if you define isEqual: in a subclass and intend to put instances of that subclass into a collection. Make sure you also define hash in your subclass." https://developer.apple.com/documentation/objectivec/1418956-nsobject/1418795-isequal?language=objc In many or all versions of libobjc, -[NSObject isEqual:] is a pointer equality check and -[NSObject hash] returns the messaged object's pointer. A relatively common form of developer error is for a developer to override -isEqual: in a subclass without overriding -hash to ensure that hashes are equal for objects that are equal. It is assumed that an override of -isEqual: is a strong signal for changing the object's equality operator to something other than pointer equality which implies that a missing override of -hash could result in distinct objects being equal but having distinct hashes because they are independent instances. This added check flags classes that override -isEqual: but inherit NSObject's implementation of -hash to warn of the potential for unexpected behavior. The proper implementation of -hash is the responsibility of the developer and the check will only verify that the developer made an effort to properly implement -hash. Developers can set up unit tests to verify that their implementation of -hash is appropriate. Test Notes: Ran check-clang-tools. Reviewers: aaron.ballman, benhamilton Reviewed By: aaron.ballman Subscribers: Eugene.Zelenko, mgorny, xazax.hun, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D67737 llvm-svn: 372445
56 lines
1.8 KiB
C++
56 lines
1.8 KiB
C++
//===--- ObjCTidyModule.cpp - clang-tidy --------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "../ClangTidy.h"
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#include "../ClangTidyModule.h"
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#include "../ClangTidyModuleRegistry.h"
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#include "AvoidNSErrorInitCheck.h"
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#include "AvoidSpinlockCheck.h"
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#include "ForbiddenSubclassingCheck.h"
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#include "MissingHashCheck.h"
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#include "PropertyDeclarationCheck.h"
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#include "SuperSelfCheck.h"
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using namespace clang::ast_matchers;
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namespace clang {
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namespace tidy {
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namespace objc {
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class ObjCModule : public ClangTidyModule {
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public:
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void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
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CheckFactories.registerCheck<AvoidNSErrorInitCheck>(
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"objc-avoid-nserror-init");
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CheckFactories.registerCheck<AvoidSpinlockCheck>(
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"objc-avoid-spinlock");
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CheckFactories.registerCheck<ForbiddenSubclassingCheck>(
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"objc-forbidden-subclassing");
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CheckFactories.registerCheck<MissingHashCheck>(
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"objc-missing-hash");
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CheckFactories.registerCheck<PropertyDeclarationCheck>(
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"objc-property-declaration");
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CheckFactories.registerCheck<SuperSelfCheck>(
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"objc-super-self");
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}
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};
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// Register the ObjCTidyModule using this statically initialized variable.
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static ClangTidyModuleRegistry::Add<ObjCModule> X(
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"objc-module",
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"Adds Objective-C lint checks.");
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} // namespace objc
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// This anchor is used to force the linker to link in the generated object file
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// and thus register the ObjCModule.
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volatile int ObjCModuleAnchorSource = 0;
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} // namespace tidy
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} // namespace clang
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