The explanation for the conditional introduced by
61d9f201baeef4c4bb91ad8a8f5f89b747e0dfe4 is longer than a reasonable
inline comment should be. It directed the reader to use `git blame`,
but that tends to bitrot. Let's point the user to a specific nixpkgs
git hash.
This commit cannot be squashed into the previous commit, because a
commit cannot mention its own commit-hash (without performaing an
expensive double-sha1 preimage attack, of course).
boost-context changed its name for mips from "mips1" to "mips" in this
commit:
6edc8184a7
however the native-build code to detect the local architecture still
reports "mips1":
67c074b249/boostcpp.jam (L637)
Therefore native builds of boost-context on mips must specify
architecture= explicitly; without this you will get link failures
"undefined reference to `jump_fcontext`" in code that uses
boost-context.
Currently the "cross compile" codepath, which provides explicit
architecture/abi/address-model/binary-format/os parameters, is
prefixed by this comment:
```
# TODO: make this unconditional
```
This commit does so, at least if `isMips`.
This commit is needed in order for native builds of nix to succeed on
mips.
This commit makes two changes:
1. Boost changed its taxonomy for architecture names between the 1.77 and
1.78 releases, in this commit:
6edc8184a7
2. During the review of #161162 I [was asked about][1] the source of
the [mips64-context.patch][2] that I had included in the original
version of the PR. I searched through the boost-context revision
history and found [a nearly identical patch][3], which I
substituted in the final, merged version of the PR.
As it turns out, my [mips64-context.patch][2] was an earlier
revision of what was eventually accepted to boost-context. The
only difference between the two patches is the name they use:
mips64 vs mips1.
When switching to the accepted version of the boost patch, I should
have also updated libraries/boost/generic.nix to change mips64 to
mips1. This commit does that.
[1]: https://github.com/NixOS/nixpkgs/pull/161162#discussion_r847903087
[2]: https://raw.githubusercontent.com/a-m-joseph/nixpkgs/1ca5025945470ce96408552b9117674b12efaf04/pkgs/development/libraries/boost/mips64-context.patch
[3]: e3f744a186.patch
Prior needsUserConfig setting is unconditionally applied for darwin.
This is not valid for static builds and should only be set for dynamically linked darwin builds.
To quote the release-notes[1]:
> When _DYNAMIC_STACK_SIZE_SOURCE or _GNU_SOURCE are defined,
> PTHREAD_STACK_MIN is no longer constant and is redefined to
> sysconf(_SC_THREAD_STACK_MIN). This supports dynamic sized register
> sets for modern architectural features like Arm SVE.
This basically means that if the above applies, `#if PTHREAD_STACK_MIN > 0`
won't compile anymore because `PTHREAD_STACK_MIN` isn't a hard-coded
number, but `__sysconf (__SC_THREAD_STACK_MIN_VALUE)`[2].
The issue (for 1.69, 1.70, 1.72 - the other versions seem OK) was
reported upstream, but only for Solaris[3], however the corresponding
patches[4] seem to work as well for us.
Failing Hydra build: https://hydra.nixos.org/build/150926294
[1] https://sourceware.org/pipermail/libc-alpha/2021-August/129718.html
[2] See `${pkgs.glibc.dev}/include/bits/pthread_stack_min-dynamic.h`
[3] https://github.com/boostorg/thread/issues/283
[4] https://github.com/conan-io/conan-center-index/pull/361