forked from OSchip/llvm-project
[clang] Implement -Wcast-qual for C++
Summary: This way, the behavior of that warning flag more closely resembles that of GCC. Do note that there is at least one false-negative (see FIXME in tests). Fixes PR4802. Testing: ``` ninja check-clang-sema check-clang-semacxx ``` Reviewers: dblaikie, majnemer, rnk Reviewed By: dblaikie, rnk Subscribers: cfe-commits, alexfh, rnk Differential Revision: https://reviews.llvm.org/D33102 llvm-svn: 305147
This commit is contained in:
Roman Lebedev
parent
3cca1da20c
commit
b0120740c4
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@ -52,6 +52,9 @@ Major New Features
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Improvements to Clang's diagnostics
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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- -Wcast-qual was implemented for C++. C-style casts are now properly
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diagnosed.
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- -Wunused-lambda-capture warns when a variable explicitly captured
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by a lambda is not used in the body of the lambda.
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@ -143,6 +143,9 @@ namespace {
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};
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}
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static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
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QualType DestType);
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// The Try functions attempt a specific way of casting. If they succeed, they
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// return TC_Success. If their way of casting is not appropriate for the given
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// arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
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@ -427,6 +430,10 @@ static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
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/// the same kind of pointer (plain or to-member). Unlike the Sema function,
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/// this one doesn't care if the two pointers-to-member don't point into the
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/// same class. This is because CastsAwayConstness doesn't care.
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/// And additionally, it handles C++ references. If both the types are
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/// references, then their pointee types are returned,
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/// else if only one of them is reference, it's pointee type is returned,
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/// and the other type is returned as-is.
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static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) {
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const PointerType *T1PtrType = T1->getAs<PointerType>(),
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*T2PtrType = T2->getAs<PointerType>();
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@ -475,6 +482,26 @@ static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) {
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return true;
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}
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const LValueReferenceType *T1RefType = T1->getAs<LValueReferenceType>(),
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*T2RefType = T2->getAs<LValueReferenceType>();
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if (T1RefType && T2RefType) {
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T1 = T1RefType->getPointeeType();
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T2 = T2RefType->getPointeeType();
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return true;
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}
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if (T1RefType) {
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T1 = T1RefType->getPointeeType();
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// T2 = T2;
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return true;
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}
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if (T2RefType) {
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// T1 = T1;
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T2 = T2RefType->getPointeeType();
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return true;
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}
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return false;
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}
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@ -503,11 +530,13 @@ CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
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// the rules are non-trivial. So first we construct Tcv *...cv* as described
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// in C++ 5.2.11p8.
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assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
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SrcType->isBlockPointerType()) &&
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SrcType->isBlockPointerType() ||
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DestType->isLValueReferenceType()) &&
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"Source type is not pointer or pointer to member.");
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assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
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DestType->isBlockPointerType()) &&
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"Destination type is not pointer or pointer to member.");
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DestType->isBlockPointerType() ||
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DestType->isLValueReferenceType()) &&
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"Destination type is not pointer or pointer to member, or reference.");
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QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
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UnwrappedDestType = Self.Context.getCanonicalType(DestType);
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@ -2177,6 +2206,8 @@ static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
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void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle,
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bool ListInitialization) {
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assert(Self.getLangOpts().CPlusPlus);
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// Handle placeholders.
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if (isPlaceholder()) {
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// C-style casts can resolve __unknown_any types.
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@ -2580,14 +2611,27 @@ void CastOperation::CheckCStyleCast() {
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if (Kind == CK_BitCast)
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checkCastAlign();
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}
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/// DiagnoseCastQual - Warn whenever casts discards a qualifiers, be it either
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/// const, volatile or both.
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static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
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QualType DestType) {
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if (SrcExpr.isInvalid())
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return;
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QualType SrcType = SrcExpr.get()->getType();
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if (!((SrcType->isAnyPointerType() && DestType->isAnyPointerType()) ||
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DestType->isLValueReferenceType()))
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return;
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// -Wcast-qual
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QualType TheOffendingSrcType, TheOffendingDestType;
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Qualifiers CastAwayQualifiers;
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if (SrcType->isAnyPointerType() && DestType->isAnyPointerType() &&
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CastsAwayConstness(Self, SrcType, DestType, true, false,
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if (!CastsAwayConstness(Self, SrcType, DestType, true, false,
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&TheOffendingSrcType, &TheOffendingDestType,
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&CastAwayQualifiers)) {
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&CastAwayQualifiers))
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return;
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int qualifiers = -1;
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if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) {
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qualifiers = 0;
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@ -2598,12 +2642,11 @@ void CastOperation::CheckCStyleCast() {
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}
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// This is a variant of int **x; const int **y = (const int **)x;
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if (qualifiers == -1)
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Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual2) <<
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SrcType << DestType;
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Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual2)
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<< SrcType << DestType;
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else
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Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual) <<
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TheOffendingSrcType << TheOffendingDestType << qualifiers;
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}
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Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual)
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<< TheOffendingSrcType << TheOffendingDestType << qualifiers;
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}
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ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc,
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@ -2624,6 +2667,9 @@ ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc,
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if (Op.SrcExpr.isInvalid())
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return ExprError();
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// -Wcast-qual
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DiagnoseCastQual(Op.Self, Op.SrcExpr, Op.DestType);
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return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType,
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Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
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&Op.BasePath, CastTypeInfo, LPLoc, RPLoc));
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@ -1,4 +1,5 @@
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// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsyntax-only -Wcast-qual -verify %s
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// RUN: %clang_cc1 -triple x86_64-unknown-unknown -x c++ -fsyntax-only -Wcast-qual -verify %s
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#include <stdint.h>
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@ -26,4 +27,34 @@ void foo() {
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const char **charptrptrc;
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char **charptrptr = (char **)charptrptrc; // expected-warning {{cast from 'const char *' to 'char *' drops const qualifier}}
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const char *constcharptr;
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char *charptr = (char *)constcharptr; // expected-warning {{cast from 'const char *' to 'char *' drops const qualifier}}
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const char *constcharptr2 = (char *)constcharptr; // expected-warning {{cast from 'const char *' to 'char *' drops const qualifier}}
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const char *charptr2 = (char *)charptr; // no warning
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}
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void bar_0() {
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struct C {
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const int a;
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int b;
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};
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const struct C S = {0, 0};
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*(int *)(&S.a) = 0; // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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*(int *)(&S.b) = 0; // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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}
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void bar_1() {
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struct C {
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const int a;
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int b;
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};
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struct C S = {0, 0};
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S.b = 0; // no warning
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*(int *)(&S.a) = 0; // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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*(int *)(&S.b) = 0; // no warning
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}
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@ -0,0 +1,140 @@
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// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsyntax-only -Wcast-qual -verify %s
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#include <stdint.h>
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// do *NOT* warn on const_cast<>()
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// use clang-tidy's cppcoreguidelines-pro-type-const-cast for that.
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void foo_ptr() {
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const char *const ptr = 0;
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char *t0 = const_cast<char *>(ptr); // no warning
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volatile char *ptr2 = 0;
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char *t1 = const_cast<char *>(ptr2); // no warning
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const volatile char *ptr3 = 0;
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char *t2 = const_cast<char *>(ptr3); // no warning
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}
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void cstr() {
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void* p0 = (void*)(const void*)"txt"; // expected-warning {{cast from 'const void *' to 'void *' drops const qualifier}}
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void* p1 = (void*)"txt"; // FIXME
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char* p2 = (char*)"txt"; // expected-warning {{cast from 'const char *' to 'char *' drops const qualifier}}
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}
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void foo_0() {
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const int a = 0;
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const int &a0 = a; // no warning
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const int &a1 = (const int &)a; // no warning
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int &a2 = (int &)a; // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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const int &a3 = (int &)a; // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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int &a4 = (int &)((const int &)a); // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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int &a5 = (int &)((int &)a); // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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const int &a6 = (int &)((int &)a); // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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const int &a7 = (int &)((const int &)a); // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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const int &a8 = (const int &)((int &)a); // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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}
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void foo_1() {
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volatile int a = 0;
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volatile int &a0 = a; // no warning
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volatile int &a1 = (volatile int &)a; // no warning
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int &a2 = (int &)a; // expected-warning {{cast from 'volatile int' to 'int &' drops volatile qualifier}}
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volatile int &a3 = (int &)a; // expected-warning {{cast from 'volatile int' to 'int &' drops volatile qualifier}}
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int &a4 = (int &)((volatile int &)a); // expected-warning {{cast from 'volatile int' to 'int &' drops volatile qualifier}}
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int &a5 = (int &)((int &)a); // expected-warning {{cast from 'volatile int' to 'int &' drops volatile qualifier}}
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volatile int &a6 = (int &)((int &)a); // expected-warning {{cast from 'volatile int' to 'int &' drops volatile qualifier}}
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volatile int &a7 = (int &)((volatile int &)a); // expected-warning {{cast from 'volatile int' to 'int &' drops volatile qualifier}}
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volatile int &a8 = (volatile int &)((int &)a); // expected-warning {{cast from 'volatile int' to 'int &' drops volatile qualifier}}
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}
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void foo_2() {
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const volatile int a = 0;
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const volatile int &a0 = a; // no warning
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const volatile int &a1 = (const volatile int &)a; // no warning
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int &a2 = (int &)a; // expected-warning {{cast from 'const volatile int' to 'int &' drops const and volatile qualifiers}}
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const volatile int &a3 = (int &)a; // expected-warning {{cast from 'const volatile int' to 'int &' drops const and volatile qualifiers}}
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int &a4 = (int &)((const volatile int &)a); // expected-warning {{cast from 'const volatile int' to 'int &' drops const and volatile qualifiers}}
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int &a5 = (int &)((int &)a); // expected-warning {{cast from 'const volatile int' to 'int &' drops const and volatile qualifiers}}
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const volatile int &a6 = (int &)((int &)a); // expected-warning {{cast from 'const volatile int' to 'int &' drops const and volatile qualifiers}}
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const volatile int &a7 = (int &)((const volatile int &)a); // expected-warning {{cast from 'const volatile int' to 'int &' drops const and volatile qualifiers}}
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const volatile int &a8 = (const volatile int &)((int &)a); // expected-warning {{cast from 'const volatile int' to 'int &' drops const and volatile qualifiers}}
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}
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void bar_0() {
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const int *_a = 0;
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const int **a = &_a;
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int **a0 = (int **)((const int **)a); // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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int **a1 = (int **)((int **)a); // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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// const int **a2 = (int **)((int **)a);
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// const int **a3 = (int **)((const int **)a);
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const int **a4 = (const int **)((int **)a); // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}} expected-warning {{cast from 'int **' to 'const int **' must have all intermediate pointers const qualified to be safe}}
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const int **a5 = (const int **)((const int **)a); // no warning
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}
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void bar_1() {
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const int *_a = 0;
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const int *&a = _a;
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int *&a0 = (int *&)((const int *&)a); // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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int *&a1 = (int *&)((int *&)a); // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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// const int *&a2 = (int *&)((int *&)a);
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// const int *&a3 = (int *&)((const int *&)a);
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const int *&a4 = (const int *&)((int *&)a); // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}} expected-warning {{cast from 'int *' to 'const int *&' must have all intermediate pointers const qualified to be safe}}
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const int *&a5 = (const int *&)((const int *&)a); // no warning
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}
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void baz_0() {
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struct C {
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void A() {}
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void B() const {}
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};
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const C S;
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S.B();
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((C &)S).B(); // expected-warning {{cast from 'const C' to 'C &' drops const qualifier}}
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((C &)S).A(); // expected-warning {{cast from 'const C' to 'C &' drops const qualifier}}
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((C *)&S)->B(); // expected-warning {{cast from 'const C *' to 'C *' drops const qualifier}}
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((C *)&S)->A(); // expected-warning {{cast from 'const C *' to 'C *' drops const qualifier}}
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}
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void baz_1() {
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struct C {
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const int a;
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int b;
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C() : a(0) {}
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};
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{
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C S;
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S.b = 0;
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(int &)(S.a) = 0; // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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(int &)(S.b) = 0; // no warning
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*(int *)(&S.a) = 0; // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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*(int *)(&S.b) = 0; // no warning
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}
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{
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const C S;
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(int &)(S.a) = 0; // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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(int &)(S.b) = 0; // expected-warning {{cast from 'const int' to 'int &' drops const qualifier}}
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*(int *)(&S.a) = 0; // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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*(int *)(&S.b) = 0; // expected-warning {{cast from 'const int *' to 'int *' drops const qualifier}}
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}
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}
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