`build-remote-trustless-should-pass-2` test fails

[xokdvium]

Describe the bug

Functional test failed with:

nix-daemon-compat-tests> copying path '/nix/store/kx7ynipj2vbncrl11gimy0b2hdr0g2xy-builder-build-remote-input-2.sh' to 'ssh-ng://localhost'...
nix-daemon-compat-tests> copying 1 paths...
nix-daemon-compat-tests> copying path '/nix/store/i599wwmv3difl3iiw8jyx5n3s574k1ia-build-remote-input-2.drv' to 'ssh-ng://localhost'...
nix-daemon-compat-tests> building '/nix/store/i599wwmv3difl3iiw8jyx5n3s574k1ia-build-remote-input-2.drv'...
nix-daemon-compat-tests> hi
nix-daemon-compat-tests> copying 1 paths...
nix-daemon-compat-tests> copying path '/nix/store/37camrpxxmwbv0m7dc3qs252wjxjk90l-build-remote-input-2' from 'ssh-ng://localhost'...
nix-daemon-compat-tests> checking path '/nix/store/37camrpxxmwbv0m7dc3qs252wjxjk90l-build-remote-input-2'...
nix-daemon-compat-tests> path '/nix/store/37camrpxxmwbv0m7dc3qs252wjxjk90l-build-remote-input-2' is corrupted or missing!
nix-daemon-compat-tests> error: some outputs are unexpectedly invalid
nix-daemon-compat-tests> +++(build-remote-trustless.sh:17) onError
nix-daemon-compat-tests> +++(/build/source/tests/functional/common/functions.sh:241) set +x
nix-daemon-compat-tests> build-remote-trustless-should-pass-2.sh: test failed at:
nix-daemon-compat-tests>   source in build-remote-trustless.sh:17
nix-daemon-compat-tests>   main in build-remote-trustless-should-pass-2.sh:16
nix-daemon-compat-tests> 
nix-daemon-compat-tests> 

Steps To Reproduce

Occurred in PR CI: https://github.com/NixOS/nix/actions/runs/18186761924/job/51772644177?pr=14139

Expected behavior

Test does not fail

Metadata

No applicable

Additional context

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

---

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[xokdvium]

Also happens on hydra: https://hydra.nixos.org/build/308707690/nixlog/1

[xokdvium]

Managed to reproduce this locally after a lot of attempts. Building with musl seems to make the issue more likely to manifest. I've already run into similar issues in the past when we had use-after-free issues.

nix build "github:NixOS/nix/7ba3ef21a67c7d4e98ef1a91d448635d439e0f57?narHash=sha256-7X7PrGNr4v2ObVCAnicpQR52J%2B0dSHdTFXHW6/%2Bl9V4%3D#hydraJobs.buildStatic.nix-functional-tests.x86_64-linux" -L --rebuild

It might be worth it to enable address sanitizer for static builds and see what it digs up. Repro isn't reliable enough to bisect.

[Ericson2314]

@xokdvium thank you again for looking into this. I have a random suspicion that it might have to do with setting the initial coroutine as a function application with arguments (i.e. closure) in derivation goal (iirc). (Sorry that's not more precise, on phone ATM.)

[xokdvium]

coroutine as a function application with arguments (i.e. closure) in derivation goal (iirc).

Sounds about right. Coroutines must never be used with lambdas with captures. https://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines/avoid-capturing-lambda-coroutines.html#cppcoreguidelines-avoid-capturing-lambda-coroutines
Is that what you are thinking of?

[xokdvium]

More of the same failures: https://github.com/NixOS/nix/actions/runs/18262564105/job/51992516048, https://hydra.nixos.org/build/308794614/nixlog/7 might be related as well.

[Ericson2314]

Hopefully this version, #14214, doesn't case the issue.