darwin stdenv can't bootstrap on macOS 11.0 Big Sur

[LnL7]

Initial support for builds on Big Sur was added in #98541 but the initial bootstrapping stages in the stdenv still link against the libSystem library that's part of bootstrap tools. This means builds depend on having a cached stdenv built by 11.15 or earlier available.

checking whether to build debug libraries... no
checking whether to build release libraries... yes
checking whether the C compiler works... no
configure: error: in `/private/tmp/nix-build-ICU-osx-10.10.5.drv-7/ICU-531.48/build':
configure: error: C compiler cannot create executables
See `config.log' for more details
./runConfigureICU: ./configure failed
make: *** [makefile:964: /private/tmp/nix-build-ICU-osx-10.10.5.drv-7/ICU-531.48/build/Makefile] Error 1

configure:2913: checking whether the C compiler works
configure:2935: cc -DU_SHOW_CPLUSPLUS_API=1 -DU_SHOW_INTERNAL_API=1 -DU_TIMEZONE=timezone -DICU_DATA_DIR="\"/usr/share/icu/\""   -g -Os -Wglobal-constructors -fno-exceptions -fvisibility=hidden   -O2  -DSTD_INSPIRED -DMAC_OS_X_VERSION_MIN_REQUIRED=1070    conftest.c  >&5
ld: warning: passed two min versions (10.12.0, 10.12) for platform macOS. Using 10.12.
ld: file not found: /usr/lib/system/libcache.dylib for architecture x86_64
clang-7: error: linker command failed with exit code 1 (use -v to see invocation)

To Reproduce

On macOS 11.0 run

nix-build -A stdenv.__bootPackages.stdenv.__bootPackages.stdenv.__bootPackages.darwin.ICU
nix-build -A stdenv.__bootPackages.stdenv.__bootPackages.stdenv.__bootPackages.darwin.ICU --check

[LnL7]

These changes are enough to work around this and link against a tbd libSystem in the first bootstrap stages, however using fetchurl for github archives is not stable so we'll need a separate release archive for this.

https://gist.github.com/LnL7/a17a042dd21258b957279637bb6be627

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/is-there-a-plan-that-nix-can-bootstrap-itself-on-macos-big-sur/10043/2

[LnL7]

There's another issue in stage2 with Security/boot.nix which gets referenced by configd.

https://github.com/NixOS/nixpkgs/blob/master/pkgs/os-specific/darwin/apple-source-releases/Security/boot.nix#L18-L19

[thefloweringash]

There's another issue in stage2 with Security/boot.nix which gets referenced by configd.

https://github.com/NixOS/nixpkgs/blob/master/pkgs/os-specific/darwin/apple-source-releases/Security/boot.nix#L18-L19

For what it's worth, those referenced files do exist on Big Sur. Still not good for purity though.

[LnL7]

As I misread what it was symlinking.

[edude03]

@LnL7 on a clean install of Big Sur 11.0.1 on x86_64 I installed nix, cloned nixpkgs master, applied your patch and used it to try and build ICU using -I nixpkgs=/path/to/patched/nixpkgs but I'm still running into this issue. Is that expected?

[thefloweringash]

These changes are enough to work around this and link against a tbd libSystem in the first bootstrap stages, however using fetchurl for github archives is not stable so we'll need a separate release archive for this.

We've added an archive for tagged releases via github actions (NixOS/darwin-stubs#4). We should add any missing libraries and tag a release to make the tarball available.

[zkbpkp]

can anyone please elaborate on how to workaround this?
i tried the same thing @edude03 described and it didn't work for me too
i also tried switching to staging/unstable channels and that didn't work either
is there a workaround except downgrading to catalina for now?