Ensure SmallVector::insert doesn't overwrite the last element in the range with the already-moved-from value

This would cause the last element in a range to be in a moved-from state
after an insert at a non-end position, losing that value entirely in the
process.

Side note: move_backward is subtle. It copies [A, B) to C-1 and down.
(the fact that it decrements both the second and third iterators before
the first movement is the subtle part... kind of surprising, anyway)

llvm-svn: 210426

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/include/llvm/ADT/SmallVector.h b/llvm/include/llvm/ADT/SmallVector.h
index dcf0354860f..29ad250010e 100644
--- a/llvm/include/llvm/ADT/SmallVector.h
+++ b/llvm/include/llvm/ADT/SmallVector.h
@@ -488,9 +488,9 @@ public:
     }
 
     ::new ((void*) this->end()) T(::std::move(this->back()));
-    this->setEnd(this->end()+1);
     // Push everything else over.
     this->move_backward(I, this->end()-1, this->end());
+    this->setEnd(this->end()+1);
 
     // If we just moved the element we're inserting, be sure to update
     // the reference.