Warn about attempts to reinterpret_cast between two types that are
hierarchy-related at a possibly nonzero offset. Patch by Alexander Zinenko! llvm-svn: 177698
This commit is contained in:
John McCall
parent
824e5a2caa
commit
cda8083309
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@ -266,6 +266,7 @@ def Trigraphs : DiagGroup<"trigraphs">;
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def : DiagGroup<"type-limits">;
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def UndefinedReinterpretCast : DiagGroup<"undefined-reinterpret-cast">;
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def ReinterpretBaseClass : DiagGroup<"reinterpret-base-class">;
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def Unicode : DiagGroup<"unicode">;
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def UninitializedMaybe : DiagGroup<"conditional-uninitialized">;
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def UninitializedSometimes : DiagGroup<"sometimes-uninitialized">;
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@ -4491,6 +4491,14 @@ def note_parameter_here : Note<
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def err_bad_reinterpret_cast_overload : Error<
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"reinterpret_cast cannot resolve overloaded function %0 to type %1">;
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def warn_reinterpret_different_from_static : Warning<
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"'reinterpret_cast' %select{from|to}3 class %0 %select{to|from}3 its "
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"%select{virtual base|base at non-zero offset}2 %1 behaves differently from "
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"'static_cast'">, InGroup<ReinterpretBaseClass>;
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def note_reinterpret_updowncast_use_static: Note<
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"use 'static_cast' to adjust the pointer correctly while "
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"%select{upcasting|downcasting}0">;
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def err_bad_static_cast_overload : Error<
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"address of overloaded function %0 cannot be static_cast to type %1">;
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@ -19,6 +19,7 @@
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#include "clang/AST/CXXInheritance.h"
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#include "clang/AST/ExprCXX.h"
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#include "clang/AST/ExprObjC.h"
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#include "clang/AST/RecordLayout.h"
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#include "clang/Basic/PartialDiagnostic.h"
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#include "clang/Sema/Initialization.h"
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#include "llvm/ADT/SmallVector.h"
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@ -682,6 +683,88 @@ void CastOperation::CheckConstCast() {
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<< SrcExpr.get()->getType() << DestType << OpRange;
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}
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/// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
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/// or downcast between respective pointers or references.
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static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
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QualType DestType,
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SourceRange OpRange) {
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QualType SrcType = SrcExpr->getType();
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// When casting from pointer or reference, get pointee type; use original
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// type otherwise.
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const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
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const CXXRecordDecl *SrcRD =
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SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
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// Examining subobjects for records is only possible if the complete
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// definition is available. Also, template instantiation is not allowed here.
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if(!SrcRD || !SrcRD->isCompleteDefinition())
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return;
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const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
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if(!DestRD || !DestRD->isCompleteDefinition())
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return;
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enum {
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ReinterpretUpcast,
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ReinterpretDowncast
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} ReinterpretKind;
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CXXBasePaths BasePaths;
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if (SrcRD->isDerivedFrom(DestRD, BasePaths))
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ReinterpretKind = ReinterpretUpcast;
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else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
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ReinterpretKind = ReinterpretDowncast;
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else
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return;
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bool VirtualBase = true;
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bool NonZeroOffset = false;
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for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
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E = BasePaths.end();
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I != E; ++I) {
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const CXXBasePath &Path = *I;
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CharUnits Offset = CharUnits::Zero();
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bool IsVirtual = false;
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for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
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IElem != EElem; ++IElem) {
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IsVirtual = IElem->Base->isVirtual();
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if (IsVirtual)
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break;
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const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
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assert(BaseRD && "Base type should be a valid unqualified class type");
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const ASTRecordLayout &DerivedLayout =
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Self.Context.getASTRecordLayout(IElem->Class);
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Offset += DerivedLayout.getBaseClassOffset(BaseRD);
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}
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if (!IsVirtual) {
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// Don't warn if any path is a non-virtually derived base at offset zero.
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if (Offset.isZero())
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return;
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// Offset makes sense only for non-virtual bases.
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else
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NonZeroOffset = true;
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}
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VirtualBase = VirtualBase && IsVirtual;
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}
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assert((VirtualBase || NonZeroOffset) &&
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"Should have returned if has non-virtual base with zero offset");
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QualType BaseType =
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ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
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QualType DerivedType =
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ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
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Self.Diag(OpRange.getBegin(), diag::warn_reinterpret_different_from_static)
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<< DerivedType << BaseType << !VirtualBase << ReinterpretKind;
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Self.Diag(OpRange.getBegin(), diag::note_reinterpret_updowncast_use_static)
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<< ReinterpretKind;
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// TODO: emit fixits. This requires passing operator SourceRange from Parser.
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}
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/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
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/// valid.
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/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
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@ -714,8 +797,10 @@ void CastOperation::CheckReinterpretCast() {
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diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
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DestType, /*listInitialization=*/false);
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}
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} else if (tcr == TC_Success && Self.getLangOpts().ObjCAutoRefCount) {
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checkObjCARCConversion(Sema::CCK_OtherCast);
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} else if (tcr == TC_Success) {
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if (Self.getLangOpts().ObjCAutoRefCount)
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checkObjCARCConversion(Sema::CCK_OtherCast);
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DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
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}
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}
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@ -0,0 +1,234 @@
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// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Wreinterpret-base-class -Wno-unused-volatile-lvalue %s
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// PR 13824
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class A {
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};
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class DA : public A {
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};
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class DDA : public DA {
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};
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class DAo : protected A {
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};
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class DAi : private A {
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};
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class DVA : public virtual A {
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};
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class DDVA : public virtual DA {
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};
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class DMA : public virtual A, public virtual DA {
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};
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class B;
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struct C {
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// Do not fail on incompletely-defined classes.
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decltype(reinterpret_cast<C *>(0)) foo;
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decltype(reinterpret_cast<A *>((C *) 0)) bar;
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decltype(reinterpret_cast<C *>((A *) 0)) baz;
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};
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void reinterpret_not_defined_class(B *b, C *c) {
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// Should not fail if class has no definition.
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(void)*reinterpret_cast<C *>(b);
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(void)*reinterpret_cast<B *>(c);
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(void)reinterpret_cast<C &>(*b);
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(void)reinterpret_cast<B &>(*c);
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}
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void reinterpret_not_updowncast(A *pa, const A *pca, A &a, const A &ca) {
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(void)*reinterpret_cast<C *>(pa);
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(void)*reinterpret_cast<const C *>(pa);
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(void)*reinterpret_cast<volatile C *>(pa);
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(void)*reinterpret_cast<const volatile C *>(pa);
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(void)*reinterpret_cast<const C *>(pca);
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(void)*reinterpret_cast<const volatile C *>(pca);
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(void)reinterpret_cast<C &>(a);
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(void)reinterpret_cast<const C &>(a);
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(void)reinterpret_cast<volatile C &>(a);
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(void)reinterpret_cast<const volatile C &>(a);
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(void)reinterpret_cast<const C &>(ca);
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(void)reinterpret_cast<const volatile C &>(ca);
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}
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void reinterpret_pointer_downcast(A *a, const A *ca) {
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(void)*reinterpret_cast<DA *>(a);
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(void)*reinterpret_cast<const DA *>(a);
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(void)*reinterpret_cast<volatile DA *>(a);
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(void)*reinterpret_cast<const volatile DA *>(a);
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(void)*reinterpret_cast<const DA *>(ca);
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(void)*reinterpret_cast<const volatile DA *>(ca);
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(void)*reinterpret_cast<DDA *>(a);
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(void)*reinterpret_cast<DAo *>(a);
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(void)*reinterpret_cast<DAi *>(a);
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// expected-warning@+2 {{'reinterpret_cast' to class 'DVA *' from its virtual base 'A *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)*reinterpret_cast<DVA *>(a);
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// expected-warning@+2 {{'reinterpret_cast' to class 'DDVA *' from its virtual base 'A *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)*reinterpret_cast<DDVA *>(a);
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// expected-warning@+2 {{'reinterpret_cast' to class 'DMA *' from its virtual base 'A *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)*reinterpret_cast<DMA *>(a);
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}
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void reinterpret_reference_downcast(A a, A &ra, const A &cra) {
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(void)reinterpret_cast<DA &>(a);
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(void)reinterpret_cast<const DA &>(a);
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(void)reinterpret_cast<volatile DA &>(a);
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(void)reinterpret_cast<const volatile DA &>(a);
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(void)reinterpret_cast<DA &>(ra);
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(void)reinterpret_cast<const DA &>(ra);
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(void)reinterpret_cast<volatile DA &>(ra);
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(void)reinterpret_cast<const volatile DA &>(ra);
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(void)reinterpret_cast<const DA &>(cra);
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(void)reinterpret_cast<const volatile DA &>(cra);
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(void)reinterpret_cast<DDA &>(a);
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(void)reinterpret_cast<DAo &>(a);
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(void)reinterpret_cast<DAi &>(a);
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// expected-warning@+2 {{'reinterpret_cast' to class 'DVA &' from its virtual base 'A' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<DVA &>(a);
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// expected-warning@+2 {{'reinterpret_cast' to class 'DDVA &' from its virtual base 'A' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<DDVA &>(a);
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// expected-warning@+2 {{'reinterpret_cast' to class 'DMA &' from its virtual base 'A' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<DMA &>(a);
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}
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void reinterpret_pointer_upcast(DA *da, const DA *cda, DDA *dda, DAo *dao,
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DAi *dai, DVA *dva, DDVA *ddva, DMA *dma) {
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(void)*reinterpret_cast<A *>(da);
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(void)*reinterpret_cast<const A *>(da);
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(void)*reinterpret_cast<volatile A *>(da);
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(void)*reinterpret_cast<const volatile A *>(da);
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(void)*reinterpret_cast<const A *>(cda);
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(void)*reinterpret_cast<const volatile A *>(cda);
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(void)*reinterpret_cast<A *>(dda);
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(void)*reinterpret_cast<DA *>(dda);
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(void)*reinterpret_cast<A *>(dao);
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(void)*reinterpret_cast<A *>(dai);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DVA *' to its virtual base 'A *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)*reinterpret_cast<A *>(dva);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DDVA *' to its virtual base 'A *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)*reinterpret_cast<A *>(ddva);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DDVA *' to its virtual base 'DA *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)*reinterpret_cast<DA *>(ddva);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DMA *' to its virtual base 'A *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)*reinterpret_cast<A *>(dma);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DMA *' to its virtual base 'DA *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)*reinterpret_cast<DA *>(dma);
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}
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void reinterpret_reference_upcast(DA &da, const DA &cda, DDA &dda, DAo &dao,
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DAi &dai, DVA &dva, DDVA &ddva, DMA &dma) {
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(void)reinterpret_cast<A &>(da);
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(void)reinterpret_cast<const A &>(da);
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(void)reinterpret_cast<volatile A &>(da);
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(void)reinterpret_cast<const volatile A &>(da);
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(void)reinterpret_cast<const A &>(cda);
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(void)reinterpret_cast<const volatile A &>(cda);
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(void)reinterpret_cast<A &>(dda);
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(void)reinterpret_cast<DA &>(dda);
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(void)reinterpret_cast<A &>(dao);
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(void)reinterpret_cast<A &>(dai);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DVA' to its virtual base 'A &' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<A &>(dva);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DDVA' to its virtual base 'A &' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<A &>(ddva);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DDVA' to its virtual base 'DA &' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<DA &>(ddva);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DMA' to its virtual base 'A &' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<A &>(dma);
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// expected-warning@+2 {{'reinterpret_cast' from class 'DMA' to its virtual base 'DA &' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<DA &>(dma);
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}
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struct E {
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int x;
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};
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class F : public E {
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virtual int foo() { return x; }
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};
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class G : public F {
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};
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class H : public E, public A {
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};
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class I : virtual public F {
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};
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typedef const F * K;
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typedef volatile K L;
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void different_subobject_downcast(E *e, F *f, A *a) {
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// expected-warning@+2 {{'reinterpret_cast' to class 'F *' from its base at non-zero offset 'E *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<F *>(e);
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// expected-warning@+2 {{'reinterpret_cast' to class 'G *' from its base at non-zero offset 'E *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<G *>(e);
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(void)reinterpret_cast<H *>(e);
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// expected-warning@+2 {{'reinterpret_cast' to class 'I *' from its virtual base 'E *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<I *>(e);
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(void)reinterpret_cast<G *>(f);
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// expected-warning@+2 {{'reinterpret_cast' to class 'I *' from its virtual base 'F *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<I *>(f);
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(void)reinterpret_cast<H *>(a);
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// expected-warning@+2 {{'reinterpret_cast' to class 'L' (aka 'const F *volatile') from its base at non-zero offset 'E *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while downcasting}}
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(void)reinterpret_cast<L>(e);
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}
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void different_subobject_upcast(F *f, G *g, H *h, I *i) {
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// expected-warning@+2 {{'reinterpret_cast' from class 'F *' to its base at non-zero offset 'E *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<E *>(f);
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(void)reinterpret_cast<F *>(g);
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// expected-warning@+2 {{'reinterpret_cast' from class 'G *' to its base at non-zero offset 'E *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<E *>(g);
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(void)reinterpret_cast<E *>(h);
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(void)reinterpret_cast<A *>(h);
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// expected-warning@+2 {{'reinterpret_cast' from class 'I *' to its virtual base 'F *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<F *>(i);
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// expected-warning@+2 {{'reinterpret_cast' from class 'I *' to its virtual base 'E *' behaves differently from 'static_cast'}}
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// expected-note@+1 {{use 'static_cast' to adjust the pointer correctly while upcasting}}
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(void)reinterpret_cast<E *>(i);
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}
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