--keep-going does not keep going on various build failures

[colemickens]

Describe the bug

$ nix build --keep-going /some/derivation.drv^*

building '/nix/store/gqamai5zimfxj8pn32cnzx3bs1mm9bqb-libXft-riscv64-unknown-linux-gnu-2.3.6.drv'...
building '/nix/store/jqs5k02g5iy4gwxlndlvicn67zr6wrf4-libXi-riscv64-unknown-linux-gnu-1.8.drv'...
building '/nix/store/xj3h7rnfrkif27qszzr7c8bgvvikiaqd-libluv-riscv64-unknown-linux-gnu-1.44.2-1.drv'...
building '/nix/store/v8pm72cc8289bndl4l1bc5zfk855i0iv-libusb-riscv64-unknown-linux-gnu-1.0.26.drv'...
building '/nix/store/q4p13sfydrjsrslsdgvkff62n5xkgrf6-aspell-riscv64-unknown-linux-gnu-0.60.8.drv'...
error: a 'riscv64-linux' with features {} is required to build '/nix/store/03w7yyb2cqw3blz9biawkypig49lx2fc-bootstrap-tools.drv', but I am a 'x86_64-linux' with features {benchmark, big-parallel, kvm, nixos-test, recursive-nix}
Nothing to push.

I know there are more riscv64 paths that can cross-compile, or were in progress compiling, but they just get killed.

Steps To Reproduce

1. Try to build a bunch of derivations, one of which requires a "different" system, other than a supported one, to trigger this error

Expected behavior

The builds keep going until it gets to the terminal tree of derivations that can't build.

(and/or it tells me what it thinks it needs bootstrap-tools for... since most of the generation is cross-compiling fine)

nix-env --version output

╭ zeph  ~/code/nixcfg 248.81s ✘1
╰─▶ nix-env --version
nix-env (Nix) 2.15.0

Additional context

Add any other context about the problem here.

Priorities

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[thufschmitt]

That doesn't feel right, indeed. I assume this throw here should instead be a call to done with the right BuildResult and the exception message (like here).

[fricklerhandwerk]

Triaged in Nix team meeting:

• @edolstra: missing system features should not be a build error, but the overall build should still keep going
• @thufschmitt: the problem is just that it's thrown in a place where it's not caught, just a small logic error
• idea approved, please go ahead with a fix!

[nixos-discourse]

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

https://discourse.nixos.org/t/2023-05-12-nix-team-meeting-minutes-54/28197/1

[RossComputerGuy]

I tried taking a stab in #12168, #8775 provided a good unit test and I managed to get no flaky results from my testing.