[PATCH] D147991: [LLVM][Casting.h] Fix dyn_cast for std::unique_ptr.

Tue Apr 18 07:43:41 PDT 2023

bzcheeseman added a comment.

In D147991#4276650 <https://reviews.llvm.org/D147991#4276650>, @zuban32 wrote:

> @bzcheeseman I've updated the test and it passes, i.e. I wasn't able to reproduce the behavior we discussed. It seems modern c++ compilers are able to elide the calls to move constructor in such a code, I tried with gcc 9.4 and Apple aarch64 clang-14 with no success.

This makes me a bit nervous because it feels like undefined behavior unless there's some part of the standard that allows something like this. Do these tests run under ASan/UBSan? Also, I assume you don't get any warnings about use-after-move?

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  https://reviews.llvm.org/D147991/new/

https://reviews.llvm.org/D147991