Properly implement the scope restriction on the NRVO for

throw-expressions, such that we don't consider the NRVO when the
non-volatile automatic object comes from outside the innermost try
scope (C++0x [class.copymove]p13). In C++98/03, our ASTs were
incorrect but it didn't matter because IR generation doesn't actually
apply the NRVO here. In C++0x, however, we were moving from an object
when in fact we should have copied from it. Fixes PR10142 /
<rdar://problem/9714312>.





git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134548 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 164c0ce038..65f431d460 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -1543,7 +1543,8 @@ ExprResult
 Sema::PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
                                       const VarDecl *NRVOCandidate,
                                       QualType ResultType,
-                                      Expr *Value) {
+                                      Expr *Value,
+                                      bool AllowNRVO) {
   // C++0x [class.copy]p33:
   //   When the criteria for elision of a copy operation are met or would
   //   be met save for the fact that the source object is a function
@@ -1551,7 +1552,8 @@ Sema::PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
   //   overload resolution to select the constructor for the copy is first
   //   performed as if the object were designated by an rvalue.
   ExprResult Res = ExprError();
-  if (NRVOCandidate || getCopyElisionCandidate(ResultType, Value, true)) {
+  if (AllowNRVO &&
+      (NRVOCandidate || getCopyElisionCandidate(ResultType, Value, true))) {
     ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack,
                               Value->getType(), CK_LValueToRValue,
                               Value, VK_XValue);