[libcxx-commits] [PATCH] D136765: [ASan][libcxx] Annotating std::vector with all allocators

Mon Mar 20 05:31:12 PDT 2023

hans added a comment.

In D136765#4203247 <https://reviews.llvm.org/D136765#4203247>, @ldionne wrote:

> I do agree however that if someone (in this case Chrome) is using a not-yet-released snapshot of `trunk` that happens to have `_LIBCPP_CLANG_VER >= 1600` yet isn't something we've released as LLVM 16, then it's probably not reasonable for us to try to support that. Imagine coming up with that policy, I think it would mean that we can't ever rely on `_LIBCPP_CLANG_VER >= 1600` during the libc++ 16 release, which would be pretty unfortunate.

(FWIW it's ChromeOS, not Chrome, that's using an older Clang version. And if necessary they can probably patch in the needed compiler-rt changes. Also, https://libcxx.llvm.org/ technically says that clang "16-git" is supported, which is what they are using ;)

I'll stop harping on about this, but I think gating functionality on _LIBCPP_CLANG_VER isn't great for the reason we've seen here. (And Eric predicted it in his "It smells weird, and it looks weird, and I think it'll lead to bugs." comment). I'm pleased to see that it's currently only used in two places in libc++, one of which is for a deprecation warning. As mentioned above, the best would be if compiler-rt exposed some kind of feature check for this, but if we can't have that, I think `>= 17` is the way to go.

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https://reviews.llvm.org/D136765