this is in preparation for the next commit which exposes the release
information and monorepo source as overridable args (which makes it
easier for users to use their own LLVM in nixpkgs)
this commit only adds a check in the `llvm` package's postConfigure that
makes sure the LLVM source provided matches the version we were given;
the actual machinery (functionally just a cosmetic change; causes no
rebuilds) is in the next commit
The two scenarios described within where splicing doesn't handle
selecting the right package for us are observable in the following
(nix repl session):
```
> np = import <nixpkgs> { system = "x86_64-linux"; crossSystem = { config = "aarch64-linux"; }; }
> np.__splicedPackages.hello ? __spliced
true
> np.__splicedPackages.python3Packages.psutil ? __spliced
true
> np.__splicedPackages.python3.pkgs.psutil ? __spliced
false
> (np.__splicedPackages.python3.withPackages (ps: with ps; [psutil])) ? __spliced
false
```
See: #211340
Details within but ultimately there isn't a satisfying resolution for
any of the three test failures we were seeing and all three deserve
further exploration.
For the `sw_vers` macOS version issue in particular, it's possible to
observe the nixpkgs provided `CoreFoundation` vs system `CoreFoundation`
for `x86_64` and `aarch64` like so (on a host running macOS `13.0.1`):
```console
$ nix-shell -p darwin.DarwinTools --system aarch64-darwin --command "sw_vers"
ProductName: macOS
ProductVersion: 13.0.1
BuildVersion: 22A400
$ nix-shell -p darwin.DarwinTools --system x86_64-darwin --command "sw_vers"
ProductName: Mac OS X
ProductVersion: 10.16
BuildVersion: 22A400
```
Where `/System/Library/CoreServices/SystemVersion.plist` has:
```console
$ cat /System/Library/CoreServices/SystemVersion.plist | grep ProductVersion
-A 1
<key>ProductVersion</key>
<string>13.0.1</string>
```
Further:
```console
$ nix-shell -p darwin.DarwinTools --system aarch64-darwin --command 'otool -L $(which sw_vers)'
/nix/store/nb2q33ak2zif49ndcpc6m823z0vhmy8y-DarwinTools-1/bin/sw_vers:
/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1770.255.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1292.60.1)
$ nix-shell -p darwin.DarwinTools --system x86_64-darwin --command 'otool -L $(which sw_vers)'
/nix/store/88v4kjvgwl71byfpvd0baviiq7l5appc-DarwinTools-1/bin/sw_vers:
@rpath/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1454.90.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1238.60.2)
```
For the `x86_64` `sw_vers` binary we can see rpath:
```console
$ nix-shell -p darwin.DarwinTools --system x86_64-darwin --command 'otool -l $(which sw_vers)' | grep LC_RPATH -A 2 -B 1
Load command 13
cmd LC_RPATH
cmdsize 120
path /nix/store/zvr4wypbgskhhw9cawfn7mmxfa75nh8f-swift-corefoundation-unstable-2018-09-14/Library/Frameworks (offset 12)
```
And we can confirm that the nixpkgs provided `CoreFoundation` is what
ultimately gets loaded:
```console
$ nix-shell -p darwin.DarwinTools --system x86_64-darwin --command 'DYLD_PRINT_LIBRARIES=1 sw_vers'
dyld[16215]: <no uuid> /nix/store/88v4kjvgwl71byfpvd0baviiq7l5appc-DarwinTools-1/bin/sw_vers
dyld[16215]: <no uuid> /nix/store/zvr4wypbgskhhw9cawfn7mmxfa75nh8f-swift-corefoundation-unstable-2018-09-14/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
dyld[16215]: <no uuid> /nix/store/xd2a4xh8kdwq0j67hzgw720npdw5hzkk-ICU-66108/lib/libicucore.A.dylib
<snipped>
```
```bash
nix-diff \
$(nix path-info nixpkgs#legacyPackages.aarch64-darwin.darwin.DarwinTools --derivation) \
$(nix path-info nixpkgs#legacyPackages.x86_64-darwin.darwin.DarwinTools --derivation)
```
doesn't show any _obvious_ discrepancies
there are a few parts to this:
- adding darwin specific check deps
- working around referencing LLVM dylibs during the checkPhase in a
way that supports darwin
+ previously we just set `$LD_LIBRARY_PATH` and/or made some
strategic symlinks
+ now we have LLVM's `lit` config set the appropriate env vars as
needed (as is done for other LLVM subprojects)
+ in retrospect switching to `installCheckPhase` might have been the
better move..
- patching `lit` to deal with `$DYLD_LIBRARY_PATH` being purged for
new "protected" processes
more details within.
as detailed within, adding `asm/ptrace.h` leads to `asm/ptrace-abi.h`
being included which defines preprocessor symbols that clash with
identifiers used in the LLVM headers (`FS` and `CS` only defined on
i686)
This restores this check to what it originally was in #196909 (see:
https://github.com/NixOS/nixpkgs/pull/196909#discussion_r1000536298) and
lets `compiler-rt` eval successfully when trying to compile the
`llvmPackages_15` set for mingw targets (i.e. a platform that *is* GNU
but does *not* use glibc).
---
It's not clear to me what the `haveLibc` check is doing here (platforms
that seem to use glibc like `x86_64-linux` and have
`plat.libc == "glibc"` have `haveLibc = false` because `stdenv.cc.libc`
is `null`).
libc++ has switched to using `__attribute__((using_if_exists))` to handle
incomplete libc implementations; see: a9c9183ca4
These essentially require a modern C++ compiler (clang gained support in
LLVM 13: 369c648399,
gcc appears to not have support yet: https://gcc.gnu.org/bugzilla//show_bug.cgi?id=105584).
Previously this was not an issue for us (despite the transition happening
around LLVM 13) but something about the changes to the libc++/libc++-abi
build has made it so that on platforms with incomplete libc impls (i.e.
Darwin is missing `quick_exit`/`at_quick_exit`) we error during the `libcxx-abi`
build when the stdenv's (older, not supporting `using_if_exists`) compiler
tries to import libc symbols that aren't present.
The libc++ docs suggest we use a modern compiler to build libc++ anyways
(https://releases.llvm.org/15.0.0/projects/libcxx/docs/index.html#platform-and-compiler-support)
so this commit uses stdenv's containing the package set's clang to build
libcxx/libcxx-abi.
This is similar to how libc++ bootstrapping builds (https://releases.llvm.org/15.0.0/projects/libcxx/docs/BuildingLibcxx.html#bootstrapping-build)
work.
None of the patches required any touch-up; the only change of note is:
- due to changes in the libc++/libc++abi build
(https://reviews.llvm.org/D120719 and https://reviews.llvm.org/D131037)
we have to add an extra build option to the libc++ header only
build that sidesteps bits of the libc++ build config that assume
libc++-abi is present in the build:
4f827318e3/libcxx/src/CMakeLists.txt (L255-L256)
Rather than maintaining a precise set of build options that let us dodge
referencing libc++-abi variables in the libc++ header only build, we set
`LIBCXX_CXX_ABI` to `none`, as suggested by @lovesegfault.
More discussion about this here: https://github.com/NixOS/nixpkgs/pull/194634#discussion_r990267037
Co-authored-by: Bernardo Meurer <bernardo@meurer.org>
