1 files changed, 110 insertions, 5 deletions

diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index 3f46cd457a..eb11a577cb 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"
@@ -332,7 +333,7 @@ static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
     : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range,
                                                              listInitialization)
     : InitializationKind::CreateCast(/*type range?*/ range);
-  InitializationSequence sequence(S, entity, initKind, &src, 1);
+  InitializationSequence sequence(S, entity, initKind, src);
 
   assert(sequence.Failed() && "initialization succeeded on second try?");
   switch (sequence.getFailureKind()) {
@@ -682,6 +683,98 @@ void CastOperation::CheckConstCast() {
       << 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 and
+  // valid definition is available.  Also, template instantiation is not
+  // allowed here.
+  if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl())
+    return;
+
+  const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
+
+  if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl())
+    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");
+      // Don't check if any base has invalid declaration or has no definition
+      // since it has no layout info.
+      const CXXRecordDecl *Class = IElem->Class,
+                          *ClassDefinition = Class->getDefinition();
+      if (Class->isInvalidDecl() || !ClassDefinition ||
+          !ClassDefinition->isCompleteDefinition())
+        return;
+
+      const ASTRecordLayout &DerivedLayout =
+          Self.Context.getASTRecordLayout(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;
+
+  SourceLocation BeginLoc = OpRange.getBegin();
+  Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static)
+    << DerivedType << BaseType << !VirtualBase << ReinterpretKind
+    << OpRange;
+  Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static)
+    << ReinterpretKind
+    << FixItHint::CreateReplacement(BeginLoc, "static_cast");
+}
+
 /// 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 +807,10 @@ void CastOperation::CheckReinterpretCast() {
       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);
   }
 }
 
@@ -1323,7 +1418,7 @@ TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
         ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization)
     : InitializationKind::CreateCast(OpRange);
   Expr *SrcExprRaw = SrcExpr.get();
-  InitializationSequence InitSeq(Self, Entity, InitKind, &SrcExprRaw, 1);
+  InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw);
 
   // At this point of CheckStaticCast, if the destination is a reference,
   // or the expression is an overload expression this has to work. 
@@ -1357,7 +1452,7 @@ static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType,
   DestType = Self.Context.getCanonicalType(DestType);
   QualType SrcType = SrcExpr->getType();
   if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
-    if (DestTypeTmp->isLValueReferenceType() && !SrcExpr->isLValue()) {
+    if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr->isLValue()) {
       // Cannot const_cast non-lvalue to lvalue reference type. But if this
       // is C-style, static_cast might find a way, so we simply suggest a
       // message and tell the parent to keep searching.
@@ -1365,6 +1460,16 @@ static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType,
       return TC_NotApplicable;
     }
 
+    // It's not completely clear under the standard whether we can
+    // const_cast bit-field gl-values.  Doing so would not be
+    // intrinsically complicated, but for now, we say no for
+    // consistency with other compilers and await the word of the
+    // committee.
+    if (SrcExpr->refersToBitField()) {
+      msg = diag::err_bad_cxx_cast_bitfield;
+      return TC_NotApplicable;
+    }
+
     // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2
     //   [...] if a pointer to T1 can be [cast] to the type pointer to T2.
     DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());