[clang-tools-extra] r252425 - [clang-tidy] add new check cppcoreguidelines-pro-type-cstyle-cast
Matthias Gehre via cfe-commits
cfe-commits at lists.llvm.org
Sun Nov 8 13:10:39 PST 2015
Author: mgehre
Date: Sun Nov 8 15:10:39 2015
New Revision: 252425
URL: http://llvm.org/viewvc/llvm-project?rev=252425&view=rev
Log:
[clang-tidy] add new check cppcoreguidelines-pro-type-cstyle-cast
Summary:
This check flags all use of c-style casts that perform a static_cast
downcast, const_cast, or reinterpret_cast.
Use of these casts can violate type safety and cause the program to
access a
variable that is actually of type X to be accessed as if it were of an
unrelated type Z. Note that a C-style (T)expression cast means to
perform
the first of the following that is possible: a const_cast, a
static_cast, a
static_cast followed by a const_cast, a reinterpret_cast, or a
reinterpret_cast followed by a const_cast. This rule bans (T)expression
only when used to perform an unsafe cast.
This rule is part of the "Type safety" profile of the C++ Core
Guidelines, see
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#-type4-dont-use-c-style-texpression-casts-that-would-perform-a-static_cast-downcast-const_cast-or-reinterpret_cast.
Reviewers: alexfh, sbenza, bkramer, aaron.ballman
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D14096
Added:
clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp
clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.h
clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-cstyle-cast.rst
clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-cstyle-cast.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=252425&r1=252424&r2=252425&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CMakeLists.txt (original)
+++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CMakeLists.txt Sun Nov 8 15:10:39 2015
@@ -5,6 +5,7 @@ add_clang_library(clangTidyCppCoreGuidel
ProBoundsArrayToPointerDecayCheck.cpp
ProBoundsPointerArithmeticCheck.cpp
ProTypeConstCastCheck.cpp
+ ProTypeCstyleCastCheck.cpp
ProTypeReinterpretCastCheck.cpp
ProTypeStaticCastDowncastCheck.cpp
ProTypeUnionAccessCheck.cpp
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=252425&r1=252424&r2=252425&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp (original)
+++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp Sun Nov 8 15:10:39 2015
@@ -14,6 +14,7 @@
#include "ProBoundsArrayToPointerDecayCheck.h"
#include "ProBoundsPointerArithmeticCheck.h"
#include "ProTypeConstCastCheck.h"
+#include "ProTypeCstyleCastCheck.h"
#include "ProTypeReinterpretCastCheck.h"
#include "ProTypeStaticCastDowncastCheck.h"
#include "ProTypeUnionAccessCheck.h"
@@ -33,6 +34,8 @@ public:
"cppcoreguidelines-pro-bounds-pointer-arithmetic");
CheckFactories.registerCheck<ProTypeConstCastCheck>(
"cppcoreguidelines-pro-type-const-cast");
+ CheckFactories.registerCheck<ProTypeCstyleCastCheck>(
+ "cppcoreguidelines-pro-type-cstyle-cast");
CheckFactories.registerCheck<ProTypeReinterpretCastCheck>(
"cppcoreguidelines-pro-type-reinterpret-cast");
CheckFactories.registerCheck<ProTypeStaticCastDowncastCheck>(
Added: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp?rev=252425&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp (added)
+++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp Sun Nov 8 15:10:39 2015
@@ -0,0 +1,107 @@
+//===--- ProTypeCstyleCastCheck.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 "ProTypeCstyleCastCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+
+static bool needsConstCast(QualType SourceType, QualType DestType) {
+ SourceType = SourceType.getNonReferenceType();
+ DestType = DestType.getNonReferenceType();
+ while (SourceType->isPointerType() && DestType->isPointerType()) {
+ SourceType = SourceType->getPointeeType();
+ DestType = DestType->getPointeeType();
+ if (SourceType.isConstQualified() && !DestType.isConstQualified())
+ return true;
+ }
+ return false;
+}
+
+void ProTypeCstyleCastCheck::registerMatchers(MatchFinder *Finder) {
+ if (!getLangOpts().CPlusPlus)
+ return;
+
+ Finder->addMatcher(
+ cStyleCastExpr(unless(isInTemplateInstantiation())).bind("cast"), this);
+}
+
+void ProTypeCstyleCastCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *MatchedCast = Result.Nodes.getNodeAs<CStyleCastExpr>("cast");
+
+ if (MatchedCast->getCastKind() == CK_BitCast ||
+ MatchedCast->getCastKind() == CK_LValueBitCast ||
+ MatchedCast->getCastKind() == CK_IntegralToPointer ||
+ MatchedCast->getCastKind() == CK_PointerToIntegral ||
+ MatchedCast->getCastKind() == CK_ReinterpretMemberPointer) {
+ diag(MatchedCast->getLocStart(),
+ "do not use C-style cast to convert between unrelated types");
+ return;
+ }
+
+ QualType SourceType = MatchedCast->getSubExpr()->getType();
+
+ if (MatchedCast->getCastKind() == CK_BaseToDerived) {
+ const auto *SourceDecl = SourceType->getPointeeCXXRecordDecl();
+ if (!SourceDecl) // The cast is from object to reference.
+ SourceDecl = SourceType->getAsCXXRecordDecl();
+ if (!SourceDecl)
+ return;
+
+ if (SourceDecl->isPolymorphic()) {
+ // Leave type spelling exactly as it was (unlike
+ // getTypeAsWritten().getAsString() which would spell enum types 'enum
+ // X').
+ StringRef DestTypeString = Lexer::getSourceText(
+ CharSourceRange::getTokenRange(
+ MatchedCast->getLParenLoc().getLocWithOffset(1),
+ MatchedCast->getRParenLoc().getLocWithOffset(-1)),
+ *Result.SourceManager, Result.Context->getLangOpts());
+
+ auto diag_builder = diag(
+ MatchedCast->getLocStart(),
+ "do not use C-style cast to downcast from a base to a derived class; "
+ "use dynamic_cast instead");
+
+ const Expr *SubExpr =
+ MatchedCast->getSubExprAsWritten()->IgnoreImpCasts();
+ std::string CastText = ("dynamic_cast<" + DestTypeString + ">").str();
+ if (!isa<ParenExpr>(SubExpr)) {
+ CastText.push_back('(');
+ diag_builder << FixItHint::CreateInsertion(
+ Lexer::getLocForEndOfToken(SubExpr->getLocEnd(), 0,
+ *Result.SourceManager,
+ Result.Context->getLangOpts()),
+ ")");
+ }
+ auto ParenRange = CharSourceRange::getTokenRange(
+ MatchedCast->getLParenLoc(), MatchedCast->getRParenLoc());
+ diag_builder << FixItHint::CreateReplacement(ParenRange, CastText);
+ } else {
+ diag(
+ MatchedCast->getLocStart(),
+ "do not use C-style cast to downcast from a base to a derived class");
+ }
+ return;
+ }
+
+ if (MatchedCast->getCastKind() == CK_NoOp &&
+ needsConstCast(SourceType, MatchedCast->getType())) {
+ diag(MatchedCast->getLocStart(),
+ "do not use C-style cast to cast away constness");
+ }
+}
+
+} // namespace tidy
+} // namespace clang
Added: clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.h
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.h?rev=252425&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.h (added)
+++ clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.h Sun Nov 8 15:10:39 2015
@@ -0,0 +1,34 @@
+//===--- ProTypeCstyleCastCheck.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_CSTYLE_CAST_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_PRO_TYPE_CSTYLE_CAST_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+
+/// This check flags all use of C-style casts that perform a static_cast
+/// downcast, const_cast, or reinterpret_cast.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines-pro-type-cstyle-cast.html
+class ProTypeCstyleCastCheck : public ClangTidyCheck {
+public:
+ ProTypeCstyleCastCheck(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_CSTYLE_CAST_H
Added: clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-cstyle-cast.rst
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-cstyle-cast.rst?rev=252425&view=auto
==============================================================================
--- clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-cstyle-cast.rst (added)
+++ clang-tools-extra/trunk/docs/clang-tidy/checks/cppcoreguidelines-pro-type-cstyle-cast.rst Sun Nov 8 15:10:39 2015
@@ -0,0 +1,15 @@
+cppcoreguidelines-pro-type-cstyle-cast
+======================================
+
+This check flags all use of C-style casts that perform a static_cast downcast, const_cast, or reinterpret_cast.
+
+Use of these casts can violate type safety and cause the program to access a
+variable that is actually of type X to be accessed as if it were of an
+unrelated type Z. Note that a C-style (T)expression cast means to perform
+the first of the following that is possible: a const_cast, a static_cast, a
+static_cast followed by a const_cast, a reinterpret_cast, or a
+reinterpret_cast followed by a const_cast. This rule bans (T)expression
+only when used to perform an unsafe cast.
+
+This rule is part of the "Type safety" profile of the C++ Core Guidelines, see
+https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#-type4-dont-use-c-style-texpression-casts-that-would-perform-a-static_cast-downcast-const_cast-or-reinterpret_cast.
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=252425&r1=252424&r2=252425&view=diff
==============================================================================
--- clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst (original)
+++ clang-tools-extra/trunk/docs/clang-tidy/checks/list.rst Sun Nov 8 15:10:39 2015
@@ -7,6 +7,7 @@ List of clang-tidy Checks
cppcoreguidelines-pro-bounds-array-to-pointer-decay
cppcoreguidelines-pro-bounds-pointer-arithmetic
cppcoreguidelines-pro-type-const-cast
+ cppcoreguidelines-pro-type-cstyle-cast
cppcoreguidelines-pro-type-reinterpret-cast
cppcoreguidelines-pro-type-static-cast-downcast
cppcoreguidelines-pro-type-union-access
Added: clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-cstyle-cast.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-cstyle-cast.cpp?rev=252425&view=auto
==============================================================================
--- clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-cstyle-cast.cpp (added)
+++ clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-cstyle-cast.cpp Sun Nov 8 15:10:39 2015
@@ -0,0 +1,141 @@
+// RUN: %check_clang_tidy %s cppcoreguidelines-pro-type-cstyle-cast %t
+
+void reinterpretcast() {
+ int i = 0;
+ void *j;
+ j = (int*)j;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use C-style cast to convert between unrelated types [cppcoreguidelines-pro-type-cstyle-cast]
+}
+
+void constcast() {
+ int* i;
+ const int* j;
+ i = (int*)j;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use C-style cast to cast away constness
+ j = (const int*)i; // OK, const added
+ (void)j; // OK, not a const_cast
+}
+
+void const_and_reinterpret() {
+ int* i;
+ const void* j;
+ i = (int*)j;
+ // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use C-style cast to convert between unrelated types
+}
+
+class Base {
+};
+
+class Derived : public Base {
+};
+
+class Base2 {
+};
+
+class MultiDerived : public Base, public Base2 {
+};
+
+class PolymorphicBase {
+public:
+ virtual ~PolymorphicBase();
+};
+
+class PolymorphicDerived : public PolymorphicBase {
+};
+
+class PolymorphicMultiDerived : public Base, public PolymorphicBase {
+};
+
+void pointers() {
+
+ auto P0 = (Derived*)new Base();
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use C-style cast to downcast from a base to a derived class
+
+ const Base* B0;
+ auto PC0 = (const Derived*)(B0);
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: do not use C-style cast to downcast from a base to a derived class
+
+ auto P1 = (Base*)new Derived(); // OK, upcast to a public base
+ auto P2 = (Base*)new MultiDerived(); // OK, upcast to a public base
+ auto P3 = (Base2*)new MultiDerived(); // OK, upcast to a public base
+}
+
+void pointers_polymorphic() {
+
+ auto PP0 = (PolymorphicDerived*)new PolymorphicBase();
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: do not use C-style cast to downcast from a base to a derived class; use dynamic_cast instead
+ // CHECK-FIXES: auto PP0 = dynamic_cast<PolymorphicDerived*>(new PolymorphicBase());
+
+ const PolymorphicBase* B0;
+ auto PPC0 = (const PolymorphicDerived*)B0;
+ // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: do not use C-style cast to downcast from a base to a derived class; use dynamic_cast instead
+ // CHECK-FIXES: auto PPC0 = dynamic_cast<const PolymorphicDerived*>(B0);
+
+
+ auto B1 = (PolymorphicBase*)new PolymorphicDerived(); // OK, upcast to a public base
+ auto B2 = (PolymorphicBase*)new PolymorphicMultiDerived(); // OK, upcast to a public base
+ auto B3 = (Base*)new PolymorphicMultiDerived(); // OK, upcast to a public base
+}
+
+void arrays() {
+ Base ArrayOfBase[10];
+ auto A0 = (Derived*)ArrayOfBase;
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use C-style cast to downcast from a base to a derived class
+}
+
+void arrays_polymorphic() {
+ PolymorphicBase ArrayOfPolymorphicBase[10];
+ auto AP0 = (PolymorphicDerived*)ArrayOfPolymorphicBase;
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: do not use C-style cast to downcast from a base to a derived class; use dynamic_cast instead
+ // CHECK-FIXES: auto AP0 = dynamic_cast<PolymorphicDerived*>(ArrayOfPolymorphicBase);
+}
+
+void references() {
+ Base B0;
+ auto R0 = (Derived&)B0;
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use C-style cast to downcast from a base to a derived class
+ Base& RefToBase = B0;
+ auto R1 = (Derived&)RefToBase;
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: do not use C-style cast to downcast from a base to a derived class
+
+ const Base& ConstRefToBase = B0;
+ auto RC1 = (const Derived&)ConstRefToBase;
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: do not use C-style cast to downcast from a base to a derived class
+
+
+ Derived RD1;
+ auto R2 = (Base&)RD1; // OK, upcast to a public base
+}
+
+void references_polymorphic() {
+ PolymorphicBase B0;
+ auto RP0 = (PolymorphicDerived&)B0;
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: do not use C-style cast to downcast from a base to a derived class; use dynamic_cast instead
+ // CHECK-FIXES: auto RP0 = dynamic_cast<PolymorphicDerived&>(B0);
+
+ PolymorphicBase& RefToPolymorphicBase = B0;
+ auto RP1 = (PolymorphicDerived&)RefToPolymorphicBase;
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: do not use C-style cast to downcast from a base to a derived class; use dynamic_cast instead
+ // CHECK-FIXES: auto RP1 = dynamic_cast<PolymorphicDerived&>(RefToPolymorphicBase);
+
+ const PolymorphicBase& ConstRefToPolymorphicBase = B0;
+ auto RPC2 = (const PolymorphicDerived&)(ConstRefToPolymorphicBase);
+ // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: do not use C-style cast to downcast from a base to a derived class; use dynamic_cast instead
+ // CHECK-FIXES: auto RPC2 = dynamic_cast<const PolymorphicDerived&>(ConstRefToPolymorphicBase);
+
+ PolymorphicDerived d1;
+ auto RP2 = (PolymorphicBase&)d1; // OK, upcast to a public base
+}
+
+template<class B, class D>
+void templ() {
+ auto B0 = (B*)new D();
+}
+
+void templ_bad_call() {
+ templ<Derived, Base>(); //FIXME: this should trigger a warning
+}
+
+void templ_good_call() {
+ templ<Base, Derived>(); // OK, upcast to a public base
+}
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