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-rw-r--r--include/clang/AST/ExprCXX.h2
-rw-r--r--lib/AST/ExprCXX.cpp30
2 files changed, 32 insertions, 0 deletions
diff --git a/include/clang/AST/ExprCXX.h b/include/clang/AST/ExprCXX.h
index e926267f5c..9bb1a50be9 100644
--- a/include/clang/AST/ExprCXX.h
+++ b/include/clang/AST/ExprCXX.h
@@ -253,6 +253,8 @@ public:
static CXXDynamicCastExpr *CreateEmpty(ASTContext &Context,
unsigned pathSize);
+ bool isAlwaysNull() const;
+
static bool classof(const Stmt *T) {
return T->getStmtClass() == CXXDynamicCastExprClass;
}
diff --git a/lib/AST/ExprCXX.cpp b/lib/AST/ExprCXX.cpp
index 526c484677..692c2c3760 100644
--- a/lib/AST/ExprCXX.cpp
+++ b/lib/AST/ExprCXX.cpp
@@ -482,6 +482,36 @@ CXXDynamicCastExpr *CXXDynamicCastExpr::CreateEmpty(ASTContext &C,
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,