DennisMelamed created this revision. DennisMelamed added reviewers: alexfh, aaron.ballman, hokein, JonasToth. Herald added subscribers: xazax.hun, mgorny.
[clang-tidy] Flag Classes Inheriting From Structs Added a check which flags cases of a class inheriting from a struct, which can cause unintended scope issues since struct members are public by default. Patch by Dennis Melamed Repository: rCTE Clang Tools Extra https://reviews.llvm.org/D52552 Files: clang-tidy/misc/CMakeLists.txt clang-tidy/misc/ClassInheritFromStructCheck.cpp clang-tidy/misc/ClassInheritFromStructCheck.h clang-tidy/misc/MiscTidyModule.cpp docs/ReleaseNotes.rst docs/clang-tidy/checks/list.rst docs/clang-tidy/checks/misc-class-inherit-from-struct.rst test/clang-tidy/misc-class-inherit-from-struct.cpp
Index: test/clang-tidy/misc-class-inherit-from-struct.cpp =================================================================== --- /dev/null +++ test/clang-tidy/misc-class-inherit-from-struct.cpp @@ -0,0 +1,22 @@ +// RUN: %check_clang_tidy %s misc-class-inherit-from-struct %t + +struct A +{ + int a; +}; + +class B:A +// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: classes should not inherit from structs [misc-class-inherit-from-struct] +{ + int b; +}; + +class C +{ + int c; +}; + +class D:C +{ + int d; +}; Index: docs/clang-tidy/checks/misc-class-inherit-from-struct.rst =================================================================== --- /dev/null +++ docs/clang-tidy/checks/misc-class-inherit-from-struct.rst @@ -0,0 +1,18 @@ +.. title:: clang-tidy - misc-class-inherit-from-struct + +misc-class-inherit-from-struct +============================== + +Finds instances of classes inheriting from structs. Structs are meant for +storing data and are often used to maintain C compatibility. Having a class +inherit from them can lead to confusion with what type of object is being +dealt with. Additionally, the default public nature of struct members can +lead to unintentional exposure of members. + +.. code-block:: c++ + + struct A {}; + class B: public A {}; //throws an error, members of A might be + //unintentionally exposed + class C {}; + class D: public C {}; //fine Index: docs/clang-tidy/checks/list.rst =================================================================== --- docs/clang-tidy/checks/list.rst +++ docs/clang-tidy/checks/list.rst @@ -159,6 +159,7 @@ llvm-include-order llvm-namespace-comment llvm-twine-local + misc-class-inherit-from-struct misc-definitions-in-headers misc-misplaced-const misc-new-delete-overloads Index: docs/ReleaseNotes.rst =================================================================== --- docs/ReleaseNotes.rst +++ docs/ReleaseNotes.rst @@ -106,6 +106,13 @@ Detects usage of magic numbers, numbers that are used as literals instead of introduced via constants or symbols. +- New :doc:`misc-class-inherit-from-struct + <clang-tidy/checks/misc-class-inherit-from-struct>` check. + + Detects instances of classes inheriting from structs as that might lead to + unintended member access issues. + + Improvements to include-fixer ----------------------------- Index: clang-tidy/misc/MiscTidyModule.cpp =================================================================== --- clang-tidy/misc/MiscTidyModule.cpp +++ clang-tidy/misc/MiscTidyModule.cpp @@ -10,6 +10,7 @@ #include "../ClangTidy.h" #include "../ClangTidyModule.h" #include "../ClangTidyModuleRegistry.h" +#include "ClassInheritFromStructCheck.h" #include "DefinitionsInHeadersCheck.h" #include "MisplacedConstCheck.h" #include "NewDeleteOverloadsCheck.h" @@ -30,6 +31,8 @@ class MiscModule : public ClangTidyModule { public: void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override { + CheckFactories.registerCheck<ClassInheritFromStructCheck>( + "misc-class-inherit-from-struct"); CheckFactories.registerCheck<DefinitionsInHeadersCheck>( "misc-definitions-in-headers"); CheckFactories.registerCheck<MisplacedConstCheck>("misc-misplaced-const"); Index: clang-tidy/misc/ClassInheritFromStructCheck.h =================================================================== --- /dev/null +++ clang-tidy/misc/ClassInheritFromStructCheck.h @@ -0,0 +1,35 @@ +//===--- ClassInheritFromStructCheck.h - clang-tidy--------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_CLASSINHERITFROMSTRUCTCHECK_H +#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_CLASSINHERITFROMSTRUCTCHECK_H + +#include "../ClangTidy.h" + +namespace clang { +namespace tidy { +namespace misc { + +/// Matches non-implicit classes which inherit from structs +/// +/// For the user-facing documentation see: +/// http://clang.llvm.org/extra/clang-tidy/checks/misc-class-inherit-from-struct.html +class ClassInheritFromStructCheck : public ClangTidyCheck { +public: + ClassInheritFromStructCheck(StringRef Name, ClangTidyContext *Context) + : ClangTidyCheck(Name, Context) {} + void registerMatchers(ast_matchers::MatchFinder *Finder) override; + void check(const ast_matchers::MatchFinder::MatchResult &Result) override; +}; + +} // namespace misc +} // namespace tidy +} // namespace clang + +#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_CLASSINHERITFROMSTRUCTCHECK_H Index: clang-tidy/misc/ClassInheritFromStructCheck.cpp =================================================================== --- /dev/null +++ clang-tidy/misc/ClassInheritFromStructCheck.cpp @@ -0,0 +1,31 @@ +//===--- ClassInheritFromStructCheck.cpp - clang-tidy----------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "ClassInheritFromStructCheck.h" +#include "clang/AST/ASTContext.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" + +using namespace clang::ast_matchers; + +namespace clang { +namespace tidy { +namespace misc { + +void ClassInheritFromStructCheck::registerMatchers(MatchFinder *Finder) { + Finder->addMatcher(cxxRecordDecl(isClass(),unless(isImplicit()),isDerivedFrom(cxxRecordDecl(isStruct()))).bind("class"), this); +} + +void ClassInheritFromStructCheck::check(const MatchFinder::MatchResult &Result) { + const auto *MatchedDecl = Result.Nodes.getNodeAs<CXXRecordDecl>("class"); + diag(MatchedDecl->getLocation(), "classes should not inherit from structs"); +} + +} // namespace misc +} // namespace tidy +} // namespace clang Index: clang-tidy/misc/CMakeLists.txt =================================================================== --- clang-tidy/misc/CMakeLists.txt +++ clang-tidy/misc/CMakeLists.txt @@ -1,6 +1,7 @@ set(LLVM_LINK_COMPONENTS support) add_clang_library(clangTidyMiscModule + ClassInheritFromStructCheck.cpp DefinitionsInHeadersCheck.cpp MiscTidyModule.cpp MisplacedConstCheck.cpp
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