[libc++] Remove workarounds for the lack of clock_gettime on older macOS platforms
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Authored by ldionne on Feb 12 2020, 8:44 AM.

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EricWF
mclow.lists

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rGbabd3aefc919: [libc++] Remove workarounds for the lack of clock_gettime on older macOS…

Summary

This increases the Mac OS requirement for building libc++ to 10.12.
Note that it doesn't change whether the *headers* still support older
platforms -- it's only that macOS >= 10.12 is required to build the
dylib from sources.

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Repository: rG LLVM Github Monorepo

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ldionne created this revision.Feb 12 2020, 8:44 AM

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Harbormaster completed remote builds in B46334: Diff 244198.Feb 12 2020, 8:51 AM

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Note: this was suggested in https://reviews.llvm.org/D74341

Feedback on this change was requested in http://lists.llvm.org/pipermail/libcxx-dev/2020-February/000688.html and nobody objected, so I think we're good to move forward.

@EricWF @mclow.lists Good?

EricWF accepted this revision.Feb 26 2020, 2:00 PM

This revision is now accepted and ready to land.Feb 26 2020, 2:00 PM

Rebase onto master and update documentation

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This revision now requires review to proceed.Jun 5 2020, 12:21 PM

ldionne accepted this revision as: Restricted Project.Jun 5 2020, 12:22 PM

This revision is now accepted and ready to land.Jun 5 2020, 12:22 PM

Harbormaster failed remote builds in B59309: Diff 268910!Jun 5 2020, 1:28 PM

Closed by commit rGbabd3aefc919: [libc++] Remove workarounds for the lack of clock_gettime on older macOS… (authored by ldionne). · Explain WhyJun 9 2020, 10:25 AM

This revision was automatically updated to reflect the committed changes.

We're looking into bumping libc++ in chromium, and this is a problem for us. We statically link libc++, and we still support 10.11. (We _just_ dropped support for 10.10 in our last release iirc.) What do you recommend as path forward?

In D74489#2497044, @thakis wrote:

We're looking into bumping libc++ in chromium, and this is a problem for us. We statically link libc++, and we still support 10.11. (We _just_ dropped support for 10.10 in our last release iirc.) What do you recommend as path forward?

Ugh, that's unfortunate. I see two options:

We revert the patch here, or
You carry a local patch until you don't support 10.11 anymore

The underlying question I'm really curious to hear the answer to is why don't you use the system libc++.dylib? How do you make sure that you don't have ODR issues when linking against macOS system frameworks that might be linking against libc++.dylib?