Author: mgehre Date: Fri Oct 16 13:46:30 2015 New Revision: 250537 URL: http://llvm.org/viewvc/llvm-project?rev=250537&view=rev Log: [clang-tidy] add check cppcoreguidelines-pro-type-union-access
Summary: This check flags all access to members of unions. Passing unions as a whole is not flagged. Reading from a union member assumes that member was the last one written, and writing to a union member assumes another member with a nontrivial destructor had its destructor called. This is fragile because it cannot generally be enforced to be safe in the language and so relies on programmer discipline to get it right. This rule is part of the "Type safety" profile of the C++ Core Guidelines, see https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#-type7-avoid-accessing-members-of-raw-unions-prefer-variant-instead Reviewers: alexfh, sbenza, bkramer, aaron.ballman Subscribers: cfe-commits Differential Revision: http://reviews.llvm.org/D13784 Added: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.h clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-union-access.rst clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-union-access.cpp Modified: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CMakeLists.txt clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst Modified: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CMakeLists.txt URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CMakeLists.txt?rev=250537&r1=250536&r2=250537&view=diff ============================================================================== --- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CMakeLists.txt (original) +++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CMakeLists.txt Fri Oct 16 13:46:30 2015 @@ -6,6 +6,7 @@ add_clang_library(clangTidyCppCoreGuidel ProTypeConstCastCheck.cpp ProTypeReinterpretCastCheck.cpp ProTypeStaticCastDowncastCheck.cpp + ProTypeUnionAccessCheck.cpp LINK_LIBS clangAST Modified: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp?rev=250537&r1=250536&r2=250537&view=diff ============================================================================== --- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp (original) +++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp Fri Oct 16 13:46:30 2015 @@ -16,6 +16,7 @@ #include "ProTypeConstCastCheck.h" #include "ProTypeReinterpretCastCheck.h" #include "ProTypeStaticCastDowncastCheck.h" +#include "ProTypeUnionAccessCheck.h" namespace clang { namespace tidy { @@ -35,6 +36,8 @@ public: "cppcoreguidelines-pro-type-reinterpret-cast"); CheckFactories.registerCheck<ProTypeStaticCastDowncastCheck>( "cppcoreguidelines-pro-type-static-cast-downcast"); + CheckFactories.registerCheck<ProTypeUnionAccessCheck>( + "cppcoreguidelines-pro-type-union-access"); CheckFactories.registerCheck<misc::AssignOperatorSignatureCheck>( "cppcoreguidelines-c-copy-assignment-signature"); } Added: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp?rev=250537&view=auto ============================================================================== --- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp (added) +++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp Fri Oct 16 13:46:30 2015 @@ -0,0 +1,33 @@ +//===--- ProTypeUnionAccessCheck.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 "ProTypeUnionAccessCheck.h" +#include "clang/AST/ASTContext.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" + +using namespace clang::ast_matchers; + +namespace clang { +namespace tidy { + +void ProTypeUnionAccessCheck::registerMatchers(MatchFinder *Finder) { + if (!getLangOpts().CPlusPlus) + return; + + Finder->addMatcher(memberExpr(hasObjectExpression(hasType(recordDecl(isUnion())))).bind("expr"), this); +} + +void ProTypeUnionAccessCheck::check(const MatchFinder::MatchResult &Result) { + const auto *Matched = Result.Nodes.getNodeAs<MemberExpr>("expr"); + diag(Matched->getMemberLoc(), "do not access members of unions; use (boost::)variant instead"); +} + +} // namespace tidy +} // namespace clang + Added: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.h URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.h?rev=250537&view=auto ============================================================================== --- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.h (added) +++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.h Fri Oct 16 13:46:30 2015 @@ -0,0 +1,35 @@ +//===--- ProTypeUnionAccessCheck.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_CPPCOREGUIDELINES_PRO_TYPE_UNION_ACCESS_H +#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_PRO_TYPE_UNION_ACCESS_H + +#include "../ClangTidy.h" + +namespace clang { +namespace tidy { + +/// This check flags all access to members of unions. +/// Access to a union as a whole (e.g. passing to a function) is not flagged. +/// +/// For the user-facing documentation see: +/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines-pro-type-union-access.html +class ProTypeUnionAccessCheck : public ClangTidyCheck { +public: + ProTypeUnionAccessCheck(StringRef Name, ClangTidyContext *Context) + : ClangTidyCheck(Name, Context) {} + void registerMatchers(ast_matchers::MatchFinder *Finder) override; + void check(const ast_matchers::MatchFinder::MatchResult &Result) override; +}; + +} // namespace tidy +} // namespace clang + +#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_PRO_TYPE_UNION_ACCESS_H + Added: clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-union-access.rst URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-union-access.rst?rev=250537&view=auto ============================================================================== --- clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-union-access.rst (added) +++ clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-union-access.rst Fri Oct 16 13:46:30 2015 @@ -0,0 +1,9 @@ +cppcoreguidelines-pro-type-union-access +======================================= + +This check flags all access to members of unions. Passing unions as a whole is not flagged. + +Reading from a union member assumes that member was the last one written, and writing to a union member assumes another member with a nontrivial destructor had its destructor called. This is fragile because it cannot generally be enforced to be safe in the language and so relies on programmer discipline to get it right. + +This rule is part of the "Type safety" profile of the C++ Core Guidelines, see +https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#-type7-avoid-accessing-members-of-raw-unions-prefer-variant-instead Modified: clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst?rev=250537&r1=250536&r2=250537&view=diff ============================================================================== --- clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst (original) +++ clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst Fri Oct 16 13:46:30 2015 @@ -8,6 +8,7 @@ List of clang-tidy Checks cppcoreguidelines-pro-type-const-cast cppcoreguidelines-pro-type-reinterpret-cast cppcoreguidelines-pro-type-static-cast-downcast + cppcoreguidelines-pro-type-union-access google-build-explicit-make-pair google-build-namespaces google-build-using-namespace Added: clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-union-access.cpp URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-union-access.cpp?rev=250537&view=auto ============================================================================== --- clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-union-access.cpp (added) +++ clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-union-access.cpp Fri Oct 16 13:46:30 2015 @@ -0,0 +1,41 @@ +// RUN: %python %S/check_clang_tidy.py %s cppcoreguidelines-pro-type-union-access %t + +union U { + bool union_member1; + char union_member2; +} u; + +struct S { + int non_union_member; + union { + bool union_member; + }; + union { + char union_member2; + } u; +} s; + + +void f(char); +void f2(U); +void f3(U&); +void f4(U*); + +void check() +{ + u.union_member1 = true; + // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not access members of unions; use (boost::)variant instead [cppcoreguidelines-pro-type-union-access] + auto b = u.union_member2; + // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: do not access members of unions; use (boost::)variant instead + auto a = &s.union_member; + // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: do not access members of unions; use (boost::)variant instead + f(s.u.union_member2); + // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: do not access members of unions; use (boost::)variant instead + + s.non_union_member = 2; // OK + + U u2 = u; // OK + f2(u); // OK + f3(u); // OK + f4(&u); // OK +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
