Provide a real fix for PR6199, reverting the old workaround. Here, we

realize that CXXConstructExpr is always implicit, so we should just
return its argument (if there is only one) rather than directly
invoking the constructor.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@95192 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CGExprCXX.cpp

@@ -309,9 +309,7 @@ CodeGenFunction::EmitCXXConstructExpr(llvm::Value *Dest,
   if (getContext().getLangOptions().ElideConstructors && E->isElidable()) {
     const Expr *Arg = E->getArg(0);
     
-    // FIXME: This 'while' statement should really be an 'if' statement, it's 
-    // added as a workaround for PR6199.
-    while (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) {
+    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) {
       assert((ICE->getCastKind() == CastExpr::CK_NoOp ||
               ICE->getCastKind() == CastExpr::CK_ConstructorConversion ||
               ICE->getCastKind() == CastExpr::CK_UserDefinedConversion) &&

lib/Sema/TreeTransform.h

@@ -4808,6 +4808,12 @@ TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
 template<typename Derived>
 Sema::OwningExprResult
 TreeTransform<Derived>::TransformCXXConstructExpr(CXXConstructExpr *E) {
+  // CXXConstructExprs are always implicit, so when we have a
+  // 1-argument construction we just transform that argument.
+  if (E->getNumArgs() == 1 ||
+      (E->getNumArgs() > 1 && getDerived().DropCallArgument(E->getArg(1))))
+    return getDerived().TransformExpr(E->getArg(0));
+
   TemporaryBase Rebase(*this, /*FIXME*/E->getLocStart(), DeclarationName());
 
   QualType T = getDerived().TransformType(E->getType());