Warn about attempts to reinterpret_cast between two types that are
hierarchy-related at a possibly nonzero offset.
Patch by Alexander Zinenko!
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177698 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index 3f46cd4..1dbc9aa 100644
--- a/lib/Sema/SemaCast.cpp
+++ b/lib/Sema/SemaCast.cpp
@@ -19,6 +19,7 @@
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
+#include "clang/AST/RecordLayout.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Sema/Initialization.h"
#include "llvm/ADT/SmallVector.h"
@@ -682,6 +683,88 @@
<< SrcExpr.get()->getType() << DestType << OpRange;
}
+/// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
+/// or downcast between respective pointers or references.
+static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
+ QualType DestType,
+ SourceRange OpRange) {
+ QualType SrcType = SrcExpr->getType();
+ // When casting from pointer or reference, get pointee type; use original
+ // type otherwise.
+ const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
+ const CXXRecordDecl *SrcRD =
+ SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
+
+ // Examining subobjects for records is only possible if the complete
+ // definition is available. Also, template instantiation is not allowed here.
+ if(!SrcRD || !SrcRD->isCompleteDefinition())
+ return;
+
+ const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
+
+ if(!DestRD || !DestRD->isCompleteDefinition())
+ return;
+
+ enum {
+ ReinterpretUpcast,
+ ReinterpretDowncast
+ } ReinterpretKind;
+
+ CXXBasePaths BasePaths;
+
+ if (SrcRD->isDerivedFrom(DestRD, BasePaths))
+ ReinterpretKind = ReinterpretUpcast;
+ else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
+ ReinterpretKind = ReinterpretDowncast;
+ else
+ return;
+
+ bool VirtualBase = true;
+ bool NonZeroOffset = false;
+ for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
+ E = BasePaths.end();
+ I != E; ++I) {
+ const CXXBasePath &Path = *I;
+ CharUnits Offset = CharUnits::Zero();
+ bool IsVirtual = false;
+ for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
+ IElem != EElem; ++IElem) {
+ IsVirtual = IElem->Base->isVirtual();
+ if (IsVirtual)
+ break;
+ const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
+ assert(BaseRD && "Base type should be a valid unqualified class type");
+ const ASTRecordLayout &DerivedLayout =
+ Self.Context.getASTRecordLayout(IElem->Class);
+ Offset += DerivedLayout.getBaseClassOffset(BaseRD);
+ }
+ if (!IsVirtual) {
+ // Don't warn if any path is a non-virtually derived base at offset zero.
+ if (Offset.isZero())
+ return;
+ // Offset makes sense only for non-virtual bases.
+ else
+ NonZeroOffset = true;
+ }
+ VirtualBase = VirtualBase && IsVirtual;
+ }
+
+ assert((VirtualBase || NonZeroOffset) &&
+ "Should have returned if has non-virtual base with zero offset");
+
+ QualType BaseType =
+ ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
+ QualType DerivedType =
+ ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
+
+ Self.Diag(OpRange.getBegin(), diag::warn_reinterpret_different_from_static)
+ << DerivedType << BaseType << !VirtualBase << ReinterpretKind;
+ Self.Diag(OpRange.getBegin(), diag::note_reinterpret_updowncast_use_static)
+ << ReinterpretKind;
+
+ // TODO: emit fixits. This requires passing operator SourceRange from Parser.
+}
+
/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
/// valid.
/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
@@ -714,8 +797,10 @@
diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
DestType, /*listInitialization=*/false);
}
- } else if (tcr == TC_Success && Self.getLangOpts().ObjCAutoRefCount) {
- checkObjCARCConversion(Sema::CCK_OtherCast);
+ } else if (tcr == TC_Success) {
+ if (Self.getLangOpts().ObjCAutoRefCount)
+ checkObjCARCConversion(Sema::CCK_OtherCast);
+ DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
}
}