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Merge bitcoin/bitcoin#27676: macOS: Bump minimum required runtime version and prepare for building with upstream LLVM
3df6070 contrib: remove macOS lazy_bind check (fanquake)
9bc357e build: explicitly opt-in to new fixup_chains functionality for darwin (Cory Fields)
fb61bc0 depends: Bump MacOS minimum runtime requirement to 11.0 (Cory Fields)
c2cd472 depends: bump darwin clang to 11.1 (Cory Fields)
Pull request description:
This (I believe) resolves the last of the blockers for [switching us away from cctools and instead using out-of-the-box llvm and lld](bitcoin/bitcoin#21778) for building Darwin binaries.
For now, we continue building with a pre-packaged llvm and cctools, but after this PR the clang+lld combo should just work for anyone trying it. Additionally after this PR, the new runtime `fixup_chains` behavior will be in-use, as ld64 uses it as well.
The commits may seem unrelated, so in detail:
lld (llvm's linker) has been a work-in-progress for Darwin for years. Recently though, it has gained nearly all of the features we require. The last missing feature from ld64, `-Wl,-bind_at_load`, is not implemented in lld; as far as I can tell [lazy loading has conceptually been replaced by fixup chains](https://www.emergetools.com/blog/posts/iOS15LaunchTime).
So that means we don't need ld64's `bind_at_load` as long as lld can handle `-Wl,-fixup_chains` (which it can). I've added it to our configure as a linker option mostly so that we can see it in the logs; it's default-on as long as the minimum version is >11.0.
About that: the runtime functionality required for `-Wl,-fixup_chains` [requires macOS >=11.0](https://github.com/llvm/llvm-project/blob/release/16.x/lld/MachO/Driver.cpp#L1021). Hence the commit that bumps the minimum version. Our current min runtime of `10.15` has been unsupported since September 2022, so I don't expect this bump to be controversial.
Lastly, with the minimum runtime version bumped to 11.0, our current version of pre-compiled clang we use for macOS is too old to understand `-mmacosx-version-min=11.0` because it expects `=10.x`. So I've made the smallest possible bump (from 10.0.1 to 11.1.0) to a version that understands. This bump is arbitrary and unfortunate, but likely to be short-lived as we may end up replacing it with llvm+lld for v26 anyway. I've held off on bumping the SDK as I think that makes sense to do as part of the lld switch instead.
ACKs for top commit:
hebasto:
ACK 3df6070
gruve-p:
ACK bitcoin/bitcoin@3df6070
fanquake:
ACK 3df6070
TheCharlatan:
ACK 3df6070
Tree-SHA512: 0200ec4a3b88df33877ae82c15b5c04d745852550923f491a354b391cac65f88e4df116a40055c23a8cbcfcdfb9a376c6ae8fdd0e898e7b966bc213dcb5857cf
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