From a9190764345ca150e04ac05e38994edf18aee3f4 Mon Sep 17 00:00:00 2001 From: Roman Divacky Date: Fri, 21 Nov 2014 21:03:10 +0000 Subject: [PATCH] Implement -Wcast-qual, fixing #13772. Many thanks to dblaikie for his advices and suggestions! git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@222568 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/clang/Basic/DiagnosticGroups.td | 2 +- include/clang/Basic/DiagnosticSemaKinds.td | 5 +++ lib/Sema/SemaCast.cpp | 44 ++++++++++++++++++++-- test/Sema/warn-cast-qual.c | 29 ++++++++++++++ 4 files changed, 75 insertions(+), 5 deletions(-) create mode 100644 test/Sema/warn-cast-qual.c diff --git a/include/clang/Basic/DiagnosticGroups.td b/include/clang/Basic/DiagnosticGroups.td index cc4508a894..76d7a669cb 100644 --- a/include/clang/Basic/DiagnosticGroups.td +++ b/include/clang/Basic/DiagnosticGroups.td @@ -60,7 +60,7 @@ def ExternCCompat : DiagGroup<"extern-c-compat">; def KeywordCompat : DiagGroup<"keyword-compat">; def GNUCaseRange : DiagGroup<"gnu-case-range">; def CastAlign : DiagGroup<"cast-align">; -def : DiagGroup<"cast-qual">; +def CastQual : DiagGroup<"cast-qual">; def : DiagGroup<"char-align">; def Comment : DiagGroup<"comment">; def GNUComplexInteger : DiagGroup<"gnu-complex-integer">; diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td index bd95c50358..310a9b2a2f 100644 --- a/include/clang/Basic/DiagnosticSemaKinds.td +++ b/include/clang/Basic/DiagnosticSemaKinds.td @@ -6115,6 +6115,11 @@ def warn_zero_size_struct_union_compat : Warning<"%select{|empty }0" def warn_zero_size_struct_union_in_extern_c : Warning<"%select{|empty }0" "%select{struct|union}1 has size 0 in C, %select{size 1|non-zero size}2 in C++">, InGroup; +def warn_cast_qual : Warning<"cast from %0 to %1 drops %select{const and " + "volatile qualifiers|const qualifier|volatile qualifier}2">, + InGroup, DefaultIgnore; +def warn_cast_qual2 : Warning<"cast from %0 to %1 must have all intermediate " + "pointers const qualified to be safe">, InGroup, DefaultIgnore; } // End of general sema category. // inline asm. diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp index ae5436cf41..00d0775be4 100644 --- a/lib/Sema/SemaCast.cpp +++ b/lib/Sema/SemaCast.cpp @@ -142,9 +142,6 @@ namespace { }; } -static bool CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, - bool CheckCVR, bool CheckObjCLifetime); - // The Try functions attempt a specific way of casting. If they succeed, they // return TC_Success. If their way of casting is not appropriate for the given // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic @@ -462,7 +459,10 @@ static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) { /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. static bool CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, - bool CheckCVR, bool CheckObjCLifetime) { + bool CheckCVR, bool CheckObjCLifetime, + QualType *TheOffendingSrcType = nullptr, + QualType *TheOffendingDestType = nullptr, + Qualifiers *CastAwayQualifiers = nullptr) { // If the only checking we care about is for Objective-C lifetime qualifiers, // and we're not in ARC mode, there's nothing to check. if (!CheckCVR && CheckObjCLifetime && @@ -487,6 +487,8 @@ CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, // Find the qualifiers. We only care about cvr-qualifiers for the // purpose of this check, because other qualifiers (address spaces, // Objective-C GC, etc.) are part of the type's identity. + QualType PrevUnwrappedSrcType = UnwrappedSrcType; + QualType PrevUnwrappedDestType = UnwrappedDestType; while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { // Determine the relevant qualifiers at this level. Qualifiers SrcQuals, DestQuals; @@ -497,6 +499,13 @@ CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, if (CheckCVR) { RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers()); RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers()); + + if (RetainedSrcQuals != RetainedDestQuals && TheOffendingSrcType && + TheOffendingDestType && CastAwayQualifiers) { + *TheOffendingSrcType = PrevUnwrappedSrcType; + *TheOffendingDestType = PrevUnwrappedDestType; + *CastAwayQualifiers = RetainedSrcQuals - RetainedDestQuals; + } } if (CheckObjCLifetime && @@ -505,6 +514,9 @@ CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, cv1.push_back(RetainedSrcQuals); cv2.push_back(RetainedDestQuals); + + PrevUnwrappedSrcType = UnwrappedSrcType; + PrevUnwrappedDestType = UnwrappedDestType; } if (cv1.empty()) return false; @@ -2371,6 +2383,30 @@ void CastOperation::CheckCStyleCast() { if (Kind == CK_BitCast) checkCastAlign(); + + // -Wcast-qual + QualType TheOffendingSrcType, TheOffendingDestType; + Qualifiers CastAwayQualifiers; + if (SrcType->isAnyPointerType() && DestType->isAnyPointerType() && + CastsAwayConstness(Self, SrcType, DestType, true, false, + &TheOffendingSrcType, &TheOffendingDestType, + &CastAwayQualifiers)) { + int qualifiers = -1; + if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) { + qualifiers = 0; + } else if (CastAwayQualifiers.hasConst()) { + qualifiers = 1; + } else if (CastAwayQualifiers.hasVolatile()) { + qualifiers = 2; + } + // This is a variant of int **x; const int **y = (const int **)x; + if (qualifiers == -1) + Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual2) << + SrcType << DestType; + else + Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual) << + TheOffendingSrcType << TheOffendingDestType << qualifiers; + } } ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, diff --git a/test/Sema/warn-cast-qual.c b/test/Sema/warn-cast-qual.c new file mode 100644 index 0000000000..dc11f5717e --- /dev/null +++ b/test/Sema/warn-cast-qual.c @@ -0,0 +1,29 @@ +// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsyntax-only -Wcast-qual -verify %s + +#include + +void foo() { + const char * const ptr = 0; + const char * const *ptrptr = 0; + char *y = (char *)ptr; // expected-warning {{cast from 'const char *' to 'char *' drops const qualifier}} + char **y1 = (char **)ptrptr; // expected-warning {{cast from 'const char *const' to 'char *' drops const qualifier}} + const char **y2 = (const char **)ptrptr; // expected-warning {{cast from 'const char *const *' to 'const char **' drops const qualifier}} + + char *z = (char *)(uintptr_t)(const void *)ptr; // no warning + char *z1 = (char *)(const void *)ptr; // expected-warning {{cast from 'const void *' to 'char *' drops const qualifier}} + + volatile char *vol = 0; + char *vol2 = (char *)vol; // expected-warning {{cast from 'volatile char *' to 'char *' drops volatile qualifier}} + const volatile char *volc = 0; + char *volc2 = (char *)volc; // expected-warning {{cast from 'const volatile char *' to 'char *' drops const and volatile qualifiers}} + + int **intptrptr; + const int **intptrptrc = (const int **)intptrptr; // expected-warning {{cast from 'int **' to 'const int **' must have all intermediate pointers const qualified}} + volatile int **intptrptrv = (volatile int **)intptrptr; // expected-warning {{cast from 'int **' to 'volatile int **' must have all intermediate pointers const qualified}} + + int *intptr; + const int *intptrc = (const int *)intptr; // no warning + + const char **charptrptrc; + char **charptrptr = (char **)charptrptrc; // expected-warning {{cast from 'const char *' to 'char *' drops const qualifier}} +} -- 2.40.0