2 files changed, 17 insertions, 6 deletions
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 19d67bb7f8a..13d2a1be3f9 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -603,18 +603,26 @@ static bool DeclCanBeLvalue(const NamedDecl *Decl, ASTContext &Ctx) {
 ///  - reference type [C++ [expr]]
 ///
 Expr::isLvalueResult Expr::isLvalue(ASTContext &Ctx) const {
+  assert(!TR->isReferenceType() && "Expressions can't have reference type.");
+
+  isLvalueResult Res = isLvalueInternal(Ctx);
+  if (Res != LV_Valid || Ctx.getLangOptions().CPlusPlus)
+    return Res;
+
   // first, check the type (C99 6.3.2.1). Expressions with function
   // type in C are not lvalues, but they can be lvalues in C++.
-  if (!Ctx.getLangOptions().CPlusPlus && TR->isFunctionType())
+  if (TR->isFunctionType())
     return LV_NotObjectType;
 
   // Allow qualified void which is an incomplete type other than void (yuck).
   if (TR->isVoidType() && !Ctx.getCanonicalType(TR).getCVRQualifiers())
     return LV_IncompleteVoidType;
 
-  assert(!TR->isReferenceType() && "Expressions can't have reference type.");
+  return LV_Valid;
+}
 
-  // the type looks fine, now check the expression
+// Check whether the expression can be sanely treated like an l-value
+Expr::isLvalueResult Expr::isLvalueInternal(ASTContext &Ctx) const {
   switch (getStmtClass()) {
   case StringLiteralClass:  // C99 6.5.1p4
   case ObjCEncodeExprClass: // @encode behaves like its string in every way.
@@ -754,8 +762,6 @@ Expr::isLvalueResult Expr::isLvalue(ASTContext &Ctx) const {
     return LV_Valid;
   case PredefinedExprClass:
     return LV_Valid;
-  case VAArgExprClass:
-    return LV_NotObjectType;
   case CXXDefaultArgExprClass:
     return cast<CXXDefaultArgExpr>(this)->getExpr()->isLvalue(Ctx);
   case CXXConditionDeclExprClass:
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 6ce98cd28f7..36ec9c65c13 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -4245,7 +4245,12 @@ QualType Sema::CheckAddressOfOperand(Expr *op, SourceLocation OpLoc) {
 
   if (lval != Expr::LV_Valid) { // C99 6.5.3.2p1
     // The operand must be either an l-value or a function designator
-    if (!op->getType()->isFunctionType()) {
+    if (op->getType()->isFunctionType()) {
+      // Function designator is valid
+    } else if (lval == Expr::LV_IncompleteVoidType) {
+      Diag(OpLoc, diag::ext_typecheck_addrof_void)
+        << op->getSourceRange();
+    } else {
       // FIXME: emit more specific diag...
       Diag(OpLoc, diag::err_typecheck_invalid_lvalue_addrof)
         << op->getSourceRange();