[PATCH] D128927: [libc++] Always build c++experimental.a

Thu Jul 21 16:42:17 PDT 2022

ldionne added a comment.

In D128927#3665748 <https://reviews.llvm.org/D128927#3665748>, @hans wrote:

> In D128927#3662659 <https://reviews.llvm.org/D128927#3662659>, @ldionne wrote:
>
>> The weird part here is that you're configuring libc++, but you are building neither the static nor the shared library. I don't understand why you do that, and that may hide some other more fundamental issue in your setup.
>
> Yes, I wish we weren't weird.
> The reason libc++ is part of our build is that we want the headers so that our newly built Clang will be able to build c++ files. https://bugs.chromium.org/p/chromium/issues/detail?id=1067216#c7 has the background for our current situation.
>
> In https://github.com/llvm/llvm-zorg/pull/28 you mentioned that "for a couple of years now, Clang and libc++ are entirely separate projects w.r.t. how they are shipped on Apple platforms, and it doesn't make sense to build libc++ at the same time as Clang anymore".
> Does that mean the libc++ headers have moved to the SDK now, and if so from what version? If it's in the SDK version we use (I'd have to check), perhaps that would allow us to stop building like this.

Yes, the libc++ headers are in the SDK. They have been since Xcode 12 if I'm not mistaken. They are *also* still shipped in the Clang toolchain, but that will change eventually -- there are a few things blocking us from doing that, but they will go away eventually.

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https://reviews.llvm.org/D128927