r275417 - Diagnose taking address and reference binding of packed members
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Thu Jul 14 16:54:09 PDT 2016
On Thu, Jul 14, 2016 at 3:52 PM, Reid Kleckner via cfe-commits <
cfe-commits at lists.llvm.org> wrote:
> Why did we upgrade the unaligned reference binding from a warning to an
> error? That will make it hard to roll this change out across many codebases.
>
GCC has given an error on this since version 4.7. If there are cases that
GCC accepts and we reject, that sounds like a bug.
> On Thu, Jul 14, 2016 at 7:10 AM, Roger Ferrer Ibanez via cfe-commits <
> cfe-commits at lists.llvm.org> wrote:
>
>> Author: rogfer01
>> Date: Thu Jul 14 09:10:43 2016
>> New Revision: 275417
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=275417&view=rev
>> Log:
>> Diagnose taking address and reference binding of packed members
>>
>> This patch implements PR#22821.
>>
>> Taking the address of a packed member is dangerous since the reduced
>> alignment of the pointee is lost. This can lead to memory alignment
>> faults in some architectures if the pointer value is dereferenced.
>>
>> This change adds a new warning to clang emitted when taking the address
>> of a packed member. A packed member is either a field/data member
>> declared as attribute((packed)) or belonging to a struct/class
>> declared as such. The associated flag is -Waddress-of-packed-member.
>> Conversions (either implicit or via a valid casting) to pointer types
>> with lower or equal alignment requirements (e.g. void* or char*)
>> silence the warning.
>>
>> This change also adds a new error diagnostic when the user attempts to
>> bind a reference to a packed member, regardless of the alignment.
>>
>> Differential Revision: https://reviews.llvm.org/D20561
>>
>>
>>
>> Added:
>> cfe/trunk/test/Sema/address-packed-member-memops.c
>> cfe/trunk/test/Sema/address-packed.c
>> cfe/trunk/test/SemaCXX/address-packed-member-memops.cpp
>> cfe/trunk/test/SemaCXX/address-packed.cpp
>> Modified:
>> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> cfe/trunk/include/clang/Sema/Sema.h
>> cfe/trunk/lib/Sema/SemaCast.cpp
>> cfe/trunk/lib/Sema/SemaChecking.cpp
>> cfe/trunk/lib/Sema/SemaExpr.cpp
>> cfe/trunk/lib/Sema/SemaInit.cpp
>>
>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=275417&r1=275416&r2=275417&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Jul 14
>> 09:10:43 2016
>> @@ -5425,6 +5425,11 @@ def warn_pointer_indirection_from_incomp
>> "dereference of type %1 that was reinterpret_cast from type %0 has
>> undefined "
>> "behavior">,
>> InGroup<UndefinedReinterpretCast>, DefaultIgnore;
>> +def warn_taking_address_of_packed_member : Warning<
>> + "taking address of packed member %0 of class or structure %q1 may
>> result in an unaligned pointer value">,
>> + InGroup<DiagGroup<"address-of-packed-member">>;
>> +def err_binding_reference_to_packed_member : Error<
>> + "binding reference to packed member %0 of class or structure %q1">;
>>
>> def err_objc_object_assignment : Error<
>> "cannot assign to class object (%0 invalid)">;
>>
>> Modified: cfe/trunk/include/clang/Sema/Sema.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=275417&r1=275416&r2=275417&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Sema/Sema.h (original)
>> +++ cfe/trunk/include/clang/Sema/Sema.h Thu Jul 14 09:10:43 2016
>> @@ -9518,6 +9518,10 @@ private:
>> void CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
>> const Expr * const *ExprArgs);
>>
>> + /// \brief Check if we are taking the address of a packed field
>> + /// as this may be a problem if the pointer value is dereferenced.
>> + void CheckAddressOfPackedMember(Expr *rhs);
>> +
>> /// \brief The parser's current scope.
>> ///
>> /// The parser maintains this state here.
>> @@ -9596,6 +9600,51 @@ public:
>> // Emitting members of dllexported classes is delayed until the class
>> // (including field initializers) is fully parsed.
>> SmallVector<CXXRecordDecl*, 4> DelayedDllExportClasses;
>> +
>> +private:
>> + /// \brief Helper class that collects misaligned member designations
>> and
>> + /// their location info for delayed diagnostics.
>> + struct MisalignedMember {
>> + Expr *E;
>> + RecordDecl *RD;
>> + ValueDecl *MD;
>> + CharUnits Alignment;
>> +
>> + MisalignedMember() : E(), RD(), MD(), Alignment() {}
>> + MisalignedMember(Expr *E, RecordDecl *RD, ValueDecl *MD,
>> + CharUnits Alignment)
>> + : E(E), RD(RD), MD(MD), Alignment(Alignment) {}
>> + explicit MisalignedMember(Expr *E)
>> + : MisalignedMember(E, nullptr, nullptr, CharUnits()) {}
>> +
>> + bool operator==(const MisalignedMember &m) { return this->E == m.E; }
>> + };
>> + /// \brief Small set of gathered accesses to potentially misaligned
>> members
>> + /// due to the packed attribute.
>> + SmallVector<MisalignedMember, 4> MisalignedMembers;
>> +
>> + /// \brief Adds an expression to the set of gathered misaligned
>> members.
>> + void AddPotentialMisalignedMembers(Expr *E, RecordDecl *RD, ValueDecl
>> *MD,
>> + CharUnits Alignment);
>> +
>> +public:
>> + /// \brief Diagnoses the current set of gathered accesses. This
>> typically
>> + /// happens at full expression level. The set is cleared after
>> emitting the
>> + /// diagnostics.
>> + void DiagnoseMisalignedMembers();
>> +
>> + /// \brief This function checks if the expression is in the sef of
>> potentially
>> + /// misaligned members and it is converted to some pointer type T with
>> lower
>> + /// or equal alignment requirements. If so it removes it. This is
>> used when
>> + /// we do not want to diagnose such misaligned access (e.g. in
>> conversions to void*).
>> + void DiscardMisalignedMemberAddress(const Type *T, Expr *E);
>> +
>> + /// \brief This function calls Action when it determines that E
>> designates a
>> + /// misaligned member due to the packed attribute. This is used to emit
>> + /// local diagnostics like in reference binding.
>> + void RefersToMemberWithReducedAlignment(
>> + Expr *E,
>> + std::function<void(Expr *, RecordDecl *, ValueDecl *, CharUnits)>
>> Action);
>> };
>>
>> /// \brief RAII object that enters a new expression evaluation context.
>>
>> Modified: cfe/trunk/lib/Sema/SemaCast.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaCast.cpp?rev=275417&r1=275416&r2=275417&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaCast.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaCast.cpp Thu Jul 14 09:10:43 2016
>> @@ -256,6 +256,7 @@ Sema::BuildCXXNamedCast(SourceLocation O
>> Op.CheckConstCast();
>> if (Op.SrcExpr.isInvalid())
>> return ExprError();
>> + DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
>> }
>> return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType,
>> Op.ValueKind, Op.SrcExpr.get(),
>> DestTInfo,
>> @@ -279,6 +280,7 @@ Sema::BuildCXXNamedCast(SourceLocation O
>> Op.CheckReinterpretCast();
>> if (Op.SrcExpr.isInvalid())
>> return ExprError();
>> + DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
>> }
>> return Op.complete(CXXReinterpretCastExpr::Create(Context,
>> Op.ResultType,
>> Op.ValueKind, Op.Kind,
>> Op.SrcExpr.get(),
>> @@ -291,6 +293,7 @@ Sema::BuildCXXNamedCast(SourceLocation O
>> Op.CheckStaticCast();
>> if (Op.SrcExpr.isInvalid())
>> return ExprError();
>> + DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
>> }
>>
>> return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType,
>>
>> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=275417&r1=275416&r2=275417&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Thu Jul 14 09:10:43 2016
>> @@ -8302,6 +8302,8 @@ void CheckImplicitConversion(Sema &S, Ex
>>
>> DiagnoseNullConversion(S, E, T, CC);
>>
>> + S.DiscardMisalignedMemberAddress(Target, E);
>> +
>> if (!Source->isIntegerType() || !Target->isIntegerType())
>> return;
>>
>> @@ -9371,6 +9373,7 @@ void Sema::CheckCompletedExpr(Expr *E, S
>> CheckUnsequencedOperations(E);
>> if (!IsConstexpr && !E->isValueDependent())
>> CheckForIntOverflow(E);
>> + DiagnoseMisalignedMembers();
>> }
>>
>> void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
>> @@ -10916,3 +10919,67 @@ void Sema::CheckArgumentWithTypeTag(cons
>> << ArgumentExpr->getSourceRange()
>> << TypeTagExpr->getSourceRange();
>> }
>> +
>> +void Sema::AddPotentialMisalignedMembers(Expr *E, RecordDecl *RD,
>> ValueDecl *MD,
>> + CharUnits Alignment) {
>> + MisalignedMembers.emplace_back(E, RD, MD, Alignment);
>> +}
>> +
>> +void Sema::DiagnoseMisalignedMembers() {
>> + for (MisalignedMember &m : MisalignedMembers) {
>> + Diag(m.E->getLocStart(), diag::warn_taking_address_of_packed_member)
>> + << m.MD << m.RD << m.E->getSourceRange();
>> + }
>> + MisalignedMembers.clear();
>> +}
>> +
>> +void Sema::DiscardMisalignedMemberAddress(const Type *T, Expr *E) {
>> + if (!T->isPointerType())
>> + return;
>> + if (isa<UnaryOperator>(E) &&
>> + cast<UnaryOperator>(E)->getOpcode() == UO_AddrOf) {
>> + auto *Op = cast<UnaryOperator>(E)->getSubExpr()->IgnoreParens();
>> + if (isa<MemberExpr>(Op)) {
>> + auto MA = std::find(MisalignedMembers.begin(),
>> MisalignedMembers.end(),
>> + MisalignedMember(Op));
>> + if (MA != MisalignedMembers.end() &&
>> + Context.getTypeAlignInChars(T->getPointeeType()) <=
>> MA->Alignment)
>> + MisalignedMembers.erase(MA);
>> + }
>> + }
>> +}
>> +
>> +void Sema::RefersToMemberWithReducedAlignment(
>> + Expr *E,
>> + std::function<void(Expr *, RecordDecl *, ValueDecl *, CharUnits)>
>> Action) {
>> + const auto *ME = dyn_cast<MemberExpr>(E);
>> + while (ME && isa<FieldDecl>(ME->getMemberDecl())) {
>> + QualType BaseType = ME->getBase()->getType();
>> + if (ME->isArrow())
>> + BaseType = BaseType->getPointeeType();
>> + RecordDecl *RD = BaseType->getAs<RecordType>()->getDecl();
>> +
>> + ValueDecl *MD = ME->getMemberDecl();
>> + bool ByteAligned =
>> Context.getTypeAlignInChars(MD->getType()).isOne();
>> + if (ByteAligned) // Attribute packed does not have any effect.
>> + break;
>> +
>> + if (!ByteAligned &&
>> + (RD->hasAttr<PackedAttr>() || (MD->hasAttr<PackedAttr>()))) {
>> + CharUnits Alignment =
>> std::min(Context.getTypeAlignInChars(MD->getType()),
>> +
>> Context.getTypeAlignInChars(BaseType));
>> + // Notify that this expression designates a member with reduced
>> alignment
>> + Action(E, RD, MD, Alignment);
>> + break;
>> + }
>> + ME = dyn_cast<MemberExpr>(ME->getBase());
>> + }
>> +}
>> +
>> +void Sema::CheckAddressOfPackedMember(Expr *rhs) {
>> + using namespace std::placeholders;
>> + RefersToMemberWithReducedAlignment(
>> + rhs, std::bind(&Sema::AddPotentialMisalignedMembers,
>> std::ref(*this), _1,
>> + _2, _3, _4));
>> +}
>> +
>>
>> Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=275417&r1=275416&r2=275417&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaExpr.cpp Thu Jul 14 09:10:43 2016
>> @@ -6001,7 +6001,9 @@ Sema::ActOnCastExpr(Scope *S, SourceLoca
>> CheckTollFreeBridgeCast(castType, CastExpr);
>>
>> CheckObjCBridgeRelatedCast(castType, CastExpr);
>> -
>> +
>> + DiscardMisalignedMemberAddress(castType.getTypePtr(), CastExpr);
>> +
>> return BuildCStyleCastExpr(LParenLoc, castTInfo, RParenLoc, CastExpr);
>> }
>>
>> @@ -10534,6 +10536,8 @@ QualType Sema::CheckAddressOfOperand(Exp
>> if (op->getType()->isObjCObjectType())
>> return Context.getObjCObjectPointerType(op->getType());
>>
>> + CheckAddressOfPackedMember(op);
>> +
>> return Context.getPointerType(op->getType());
>> }
>>
>>
>> Modified: cfe/trunk/lib/Sema/SemaInit.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaInit.cpp?rev=275417&r1=275416&r2=275417&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaInit.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaInit.cpp Thu Jul 14 09:10:43 2016
>> @@ -6457,6 +6457,15 @@ InitializationSequence::Perform(Sema &S,
>> ExtendingEntity->getDecl());
>>
>> CheckForNullPointerDereference(S, CurInit.get());
>> +
>> + S.RefersToMemberWithReducedAlignment(CurInit.get(), [&](Expr *E,
>> + RecordDecl
>> *RD,
>> + ValueDecl
>> *MD,
>> + CharUnits)
>> {
>> + S.Diag(Kind.getLocation(),
>> diag::err_binding_reference_to_packed_member)
>> + << MD << RD << E->getSourceRange();
>> + });
>> +
>> break;
>>
>> case SK_BindReferenceToTemporary: {
>> @@ -6645,12 +6654,16 @@ InitializationSequence::Perform(Sema &S,
>> getAssignmentAction(Entity), CCK);
>> if (CurInitExprRes.isInvalid())
>> return ExprError();
>> +
>> + S.DiscardMisalignedMemberAddress(Step->Type.getTypePtr(),
>> CurInit.get());
>> +
>> CurInit = CurInitExprRes;
>>
>> if (Step->Kind == SK_ConversionSequenceNoNarrowing &&
>> S.getLangOpts().CPlusPlus &&
>> !CurInit.get()->isValueDependent())
>> DiagnoseNarrowingInInitList(S, *Step->ICS, SourceType,
>> Entity.getType(),
>> CurInit.get());
>> +
>> break;
>> }
>>
>>
>> Added: cfe/trunk/test/Sema/address-packed-member-memops.c
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/address-packed-member-memops.c?rev=275417&view=auto
>>
>> ==============================================================================
>> --- cfe/trunk/test/Sema/address-packed-member-memops.c (added)
>> +++ cfe/trunk/test/Sema/address-packed-member-memops.c Thu Jul 14
>> 09:10:43 2016
>> @@ -0,0 +1,26 @@
>> +// RUN: %clang_cc1 -fsyntax-only -verify %s
>> +// expected-no-diagnostics
>> +
>> +struct B {
>> + int x, y, z, w;
>> +} b;
>> +
>> +struct __attribute__((packed)) A {
>> + struct B b;
>> +} a;
>> +
>> +typedef __typeof__(sizeof(int)) size_t;
>> +
>> +void *memcpy(void *dest, const void *src, size_t n);
>> +int memcmp(const void *s1, const void *s2, size_t n);
>> +void *memmove(void *dest, const void *src, size_t n);
>> +void *memset(void *s, int c, size_t n);
>> +
>> +int x;
>> +
>> +void foo(void) {
>> + memcpy(&a.b, &b, sizeof(b));
>> + memmove(&a.b, &b, sizeof(b));
>> + memset(&a.b, 0, sizeof(b));
>> + x = memcmp(&a.b, &b, sizeof(b));
>> +}
>>
>> Added: cfe/trunk/test/Sema/address-packed.c
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/address-packed.c?rev=275417&view=auto
>>
>> ==============================================================================
>> --- cfe/trunk/test/Sema/address-packed.c (added)
>> +++ cfe/trunk/test/Sema/address-packed.c Thu Jul 14 09:10:43 2016
>> @@ -0,0 +1,160 @@
>> +// RUN: %clang_cc1 -fsyntax-only -verify %s
>> +extern void f1(int *);
>> +extern void f2(char *);
>> +
>> +struct Ok {
>> + char c;
>> + int x;
>> +};
>> +
>> +struct __attribute__((packed)) Arguable {
>> + char c0;
>> + int x;
>> + char c1;
>> +};
>> +
>> +union __attribute__((packed)) UnionArguable {
>> + char c;
>> + int x;
>> +};
>> +
>> +typedef struct Arguable ArguableT;
>> +
>> +struct Arguable *get_arguable();
>> +
>> +void to_void(void *);
>> +
>> +void g0(void) {
>> + {
>> + struct Ok ok;
>> + f1(&ok.x); // no-warning
>> + f2(&ok.c); // no-warning
>> + }
>> + {
>> + struct Arguable arguable;
>> + f2(&arguable.c0); // no-warning
>> + f1(&arguable.x); // expected-warning {{packed member 'x' of class
>> or structure 'Arguable'}}
>> + f2(&arguable.c1); // no-warning
>> +
>> + f1((int *)(void *)&arguable.x); // no-warning
>> + to_void(&arguable.x); // no-warning
>> + void *p = &arguable.x; // no-warning;
>> + to_void(p);
>> + }
>> + {
>> + union UnionArguable arguable;
>> + f2(&arguable.c); // no-warning
>> + f1(&arguable.x); // expected-warning {{packed member 'x' of class or
>> structure 'UnionArguable'}}
>> +
>> + f1((int *)(void *)&arguable.x); // no-warning
>> + to_void(&arguable.x); // no-warning
>> + }
>> + {
>> + ArguableT arguable;
>> + f2(&arguable.c0); // no-warning
>> + f1(&arguable.x); // expected-warning {{packed member 'x' of class
>> or structure 'Arguable'}}
>> + f2(&arguable.c1); // no-warning
>> +
>> + f1((int *)(void *)&arguable.x); // no-warning
>> + to_void(&arguable.x); // no-warning
>> + }
>> + {
>> + struct Arguable *arguable = get_arguable();
>> + f2(&arguable->c0); // no-warning
>> + f1(&arguable->x); // expected-warning {{packed member 'x' of class
>> or structure 'Arguable'}}
>> + f2(&arguable->c1); // no-warning
>> +
>> + f1((int *)(void *)&arguable->x); // no-warning
>> + to_void(&arguable->c1); // no-warning
>> + }
>> + {
>> + ArguableT *arguable = get_arguable();
>> + f2(&(arguable->c0)); // no-warning
>> + f1(&(arguable->x)); // expected-warning {{packed member 'x' of
>> class or structure 'Arguable'}}
>> + f2(&(arguable->c1)); // no-warning
>> +
>> + f1((int *)(void *)&(arguable->x)); // no-warning
>> + to_void(&(arguable->c1)); // no-warning
>> + }
>> +}
>> +
>> +struct S1 {
>> + char c;
>> + int i __attribute__((packed));
>> +};
>> +
>> +int *g1(struct S1 *s1) {
>> + return &s1->i; // expected-warning {{packed member 'i' of class or
>> structure 'S1'}}
>> +}
>> +
>> +struct S2_i {
>> + int i;
>> +};
>> +struct __attribute__((packed)) S2 {
>> + char c;
>> + struct S2_i inner;
>> +};
>> +
>> +int *g2(struct S2 *s2) {
>> + return &s2->inner.i; // expected-warning {{packed member 'inner' of
>> class or structure 'S2'}}
>> +}
>> +
>> +struct S2_a {
>> + char c;
>> + struct S2_i inner __attribute__((packed));
>> +};
>> +
>> +int *g2_a(struct S2_a *s2_a) {
>> + return &s2_a->inner.i; // expected-warning {{packed member 'inner' of
>> class or structure 'S2_a'}}
>> +}
>> +
>> +struct __attribute__((packed)) S3 {
>> + char c;
>> + struct {
>> + int i;
>> + } inner;
>> +};
>> +
>> +int *g3(struct S3 *s3) {
>> + return &s3->inner.i; // expected-warning {{packed member 'inner' of
>> class or structure 'S3'}}
>> +}
>> +
>> +struct S4 {
>> + char c;
>> + struct __attribute__((packed)) {
>> + int i;
>> + } inner;
>> +};
>> +
>> +int *g4(struct S4 *s4) {
>> + return &s4->inner.i; // expected-warning {{packed member 'i' of class
>> or structure 'S4::(anonymous)'}}
>> +}
>> +
>> +struct S5 {
>> + char c;
>> + struct {
>> + char c1;
>> + int i __attribute__((packed));
>> + } inner;
>> +};
>> +
>> +int *g5(struct S5 *s5) {
>> + return &s5->inner.i; // expected-warning {{packed member 'i' of class
>> or structure 'S5::(anonymous)'}}
>> +}
>> +
>> +struct __attribute__((packed, aligned(2))) AlignedTo2 {
>> + int x;
>> +};
>> +
>> +char *g6(struct AlignedTo2 *s) {
>> + return (char *)&s->x; // no-warning
>> +}
>> +
>> +struct __attribute__((packed, aligned(2))) AlignedTo2Bis {
>> + int x;
>> +};
>> +
>> +struct AlignedTo2Bis* g7(struct AlignedTo2 *s)
>> +{
>> + return (struct AlignedTo2Bis*)&s->x; // no-warning
>> +}
>>
>> Added: cfe/trunk/test/SemaCXX/address-packed-member-memops.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/address-packed-member-memops.cpp?rev=275417&view=auto
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/address-packed-member-memops.cpp (added)
>> +++ cfe/trunk/test/SemaCXX/address-packed-member-memops.cpp Thu Jul 14
>> 09:10:43 2016
>> @@ -0,0 +1,28 @@
>> +// RUN: %clang_cc1 -fsyntax-only -verify %s
>> +// expected-no-diagnostics
>> +
>> +struct B {
>> + int x, y, z, w;
>> +} b;
>> +
>> +struct __attribute__((packed)) A {
>> + struct B b;
>> +} a;
>> +
>> +typedef __typeof__(sizeof(int)) size_t;
>> +
>> +extern "C" {
>> +void *memcpy(void *dest, const void *src, size_t n);
>> +int memcmp(const void *s1, const void *s2, size_t n);
>> +void *memmove(void *dest, const void *src, size_t n);
>> +void *memset(void *s, int c, size_t n);
>> +}
>> +
>> +int x;
>> +
>> +void foo() {
>> + memcpy(&a.b, &b, sizeof(b));
>> + memmove(&a.b, &b, sizeof(b));
>> + memset(&a.b, 0, sizeof(b));
>> + x = memcmp(&a.b, &b, sizeof(b));
>> +}
>>
>> Added: cfe/trunk/test/SemaCXX/address-packed.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/address-packed.cpp?rev=275417&view=auto
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/address-packed.cpp (added)
>> +++ cfe/trunk/test/SemaCXX/address-packed.cpp Thu Jul 14 09:10:43 2016
>> @@ -0,0 +1,118 @@
>> +// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
>> +extern void f1(int *);
>> +extern void f2(char *);
>> +
>> +struct __attribute__((packed)) Arguable {
>> + int x;
>> + char c;
>> + static void foo();
>> +};
>> +
>> +extern void f3(void());
>> +
>> +namespace Foo {
>> +struct __attribute__((packed)) Arguable {
>> + char c;
>> + int x;
>> + static void foo();
>> +};
>> +}
>> +
>> +struct Arguable *get_arguable();
>> +
>> +void f4(int &);
>> +
>> +void to_void(void *);
>> +
>> +template <typename... T>
>> +void sink(T...);
>> +
>> +void g0() {
>> + {
>> + Foo::Arguable arguable;
>> + f1(&arguable.x); // expected-warning {{packed member 'x' of class
>> or structure 'Foo::Arguable'}}
>> + f2(&arguable.c); // no-warning
>> + f3(&arguable.foo); // no-warning
>> +
>> + int &w = arguable.x; // expected-error {{binding reference to packed
>> member 'x' of class or structure 'Foo::Arguable'}}
>> + sink(w);
>> + f4(arguable.x); // expected-error {{binding reference to packed
>> member 'x' of class or structure 'Foo::Arguable'}}
>> +
>> + to_void(&arguable.x); // no-warning
>> + void *p1 = &arguable.x; // no-warning
>> + void *p2 = static_cast<void *>(&arguable.x); // no-warning
>> + void *p3 = reinterpret_cast<void *>(&arguable.x); // no-warning
>> + void *p4 = (void *)&arguable.x; // no-warning
>> + sink(p1, p2, p3, p4);
>> + }
>> + {
>> + Arguable arguable1;
>> + Arguable &arguable(arguable1);
>> + f1(&arguable.x); // expected-warning {{packed member 'x' of class
>> or structure 'Arguable'}}
>> + f2(&arguable.c); // no-warning
>> + f3(&arguable.foo); // no-warning
>> + }
>> + {
>> + Arguable *arguable1;
>> + Arguable *&arguable(arguable1);
>> + f1(&arguable->x); // expected-warning {{packed member 'x' of class
>> or structure 'Arguable'}}
>> + f2(&arguable->c); // no-warning
>> + f3(&arguable->foo); // no-warning
>> + }
>> +}
>> +
>> +struct __attribute__((packed)) A {
>> + int x;
>> + char c;
>> +
>> + int *f0() {
>> + return &this->x; // expected-warning {{packed member 'x' of class or
>> structure 'A'}}
>> + }
>> +
>> + int *g0() {
>> + return &x; // expected-warning {{packed member 'x' of class or
>> structure 'A'}}
>> + }
>> +
>> + char *h0() {
>> + return &c; // no-warning
>> + }
>> +};
>> +
>> +struct B : A {
>> + int *f1() {
>> + return &this->x; // expected-warning {{packed member 'x' of class or
>> structure 'A'}}
>> + }
>> +
>> + int *g1() {
>> + return &x; // expected-warning {{packed member 'x' of class or
>> structure 'A'}}
>> + }
>> +
>> + char *h1() {
>> + return &c; // no-warning
>> + }
>> +};
>> +
>> +template <typename Ty>
>> +class __attribute__((packed)) S {
>> + Ty X;
>> +
>> +public:
>> + const Ty *get() const {
>> + return &X; // expected-warning {{packed member 'X' of class or
>> structure 'S<int>'}}
>> + // expected-warning at -1 {{packed member 'X' of class or
>> structure 'S<float>'}}
>> + }
>> +};
>> +
>> +template <typename Ty>
>> +void h(Ty *);
>> +
>> +void g1() {
>> + S<int> s1;
>> + s1.get(); // expected-note {{in instantiation of member function
>> 'S<int>::get'}}
>> +
>> + S<char> s2;
>> + s2.get();
>> +
>> + S<float> s3;
>> + s3.get(); // expected-note {{in instantiation of member function
>> 'S<float>::get'}}
>> +}
>>
>>
>> _______________________________________________
>> cfe-commits mailing list
>> cfe-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>>
>
>
> _______________________________________________
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> cfe-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
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