[cfe-commits] r129263 - in /cfe/trunk: include/clang/AST/ExprCXX.h lib/AST/ExprCXX.cpp

[Anders Carlsson]

Author: andersca
Date: Sun Apr 10 20:43:55 2011
New Revision: 129263

URL: http://llvm.org/viewvc/llvm-project?rev=129263&view=rev
Log:
Add CXXDynamicCastExpr::isAlwaysNull() which will be replacing the cast kind I added.

Modified:
    cfe/trunk/include/clang/AST/ExprCXX.h
    cfe/trunk/lib/AST/ExprCXX.cpp

Modified: cfe/trunk/include/clang/AST/ExprCXX.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/ExprCXX.h?rev=129263&r1=129262&r2=129263&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/ExprCXX.h (original)
+++ cfe/trunk/include/clang/AST/ExprCXX.h Sun Apr 10 20:43:55 2011
@@ -253,6 +253,8 @@
   static CXXDynamicCastExpr *CreateEmpty(ASTContext &Context,
                                          unsigned pathSize);
 
+  bool isAlwaysNull() const;
+
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == CXXDynamicCastExprClass;
   }

Modified: cfe/trunk/lib/AST/ExprCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprCXX.cpp?rev=129263&r1=129262&r2=129263&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprCXX.cpp (original)
+++ cfe/trunk/lib/AST/ExprCXX.cpp Sun Apr 10 20:43:55 2011
@@ -482,6 +482,36 @@
   return new (Buffer) CXXDynamicCastExpr(EmptyShell(), PathSize);
 }
 
+/// isAlwaysNull - Return whether the result of the dynamic_cast is proven
+/// to always be null. For example:
+///
+/// struct A { };
+/// struct B final : A { };
+/// struct C { };
+///
+/// C *f(B* b) { return dynamic_cast<C*>(b); }
+bool CXXDynamicCastExpr::isAlwaysNull() const
+{
+  QualType SrcType = getSubExpr()->getType();
+  QualType DestType = getType();
+
+  if (const PointerType *SrcPTy = SrcType->getAs<PointerType>()) {
+    SrcType = SrcPTy->getPointeeType();
+    DestType = DestType->castAs<PointerType>()->getPointeeType();
+  }
+
+  const CXXRecordDecl *SrcRD = 
+    cast<CXXRecordDecl>(SrcType->castAs<RecordType>()->getDecl());
+
+  if (!SrcRD->hasAttr<FinalAttr>())
+    return false;
+
+  const CXXRecordDecl *DestRD = 
+    cast<CXXRecordDecl>(DestType->castAs<RecordType>()->getDecl());
+
+  return !DestRD->isDerivedFrom(SrcRD);
+}
+
 CXXReinterpretCastExpr *
 CXXReinterpretCastExpr::Create(ASTContext &C, QualType T, ExprValueKind VK,
                                CastKind K, Expr *Op,