This PR achieves 3 main things:
It simplifies the macOS SDK generation by putting the logic inside a
(semi-)portable python3 script gen-sdk
It transitions us to using libc++ headers extracted from the
Xcode.app, which is more correct as those headers better match the .tbd
library stubs we use from the MacOSX.sdk (located under the same
Xcode.app). Previously, we used libc++ headers copied from our
downloaded, pinned clang (see native_cctools.mk).
It bumps the macOS toolchain in a way that fulfills all of the
following constraints:
The new SDK should support compiling with C++17 (our current one
doesn't)
The new toolchain should not change our minimum supported macOS
version (-mmacosx-version-min)
The new toolchain should expect to use a version of cctools that
is supported by https://github.com/tpoechtrager/cctools-port
For the constraints in (3), you can reference this chart to see that the
newest toolchain we can use with our cctools-port is 11.3.1, and the
rest of the constraints were tested with local builds.
But the other Wikipedia chart says that the "min macOS to run" for Xcode
11.3.1 is 10.14.4, doesn't that violate constraint (ii)?
This confused me at first too, but the "min macOS to run" is for the
Xcode.app App itself. The SDK still supports 10.12, as evident in a few
plist files and as proven through local builds.
Why bundle all of this together in a single PR?
We need (1) and (2) together, because if we don't, manually adding the
libc++ headers and writing that out in a README.md is going to result in
a lot of user error, so it's great to have these together to be more
correct and also make it easier on the user at the same time.
We need (3) together with everything else because bumping (or in the
case of (1), renaming) the SDK requires some human coordination and may
break some builds. And since it's not that complicated a change, it
makes sense to do it together with the rest.Backport of core PR19240.
Changes from the original PR:
- Keep using the clang binary for Ubuntu 16.04 instead of 14.04
- Integrate https://github.com/bitcoin-core/apple-sdk-tools into our
mono-repo and update the doc accordingly
- Update the gitian.sh script for our CI.
- Adapted the build for cmake