runCommand fails when using __structuredAttrs

[lunik1]

Describe the bug

The trivial runCommand builder (and friends) fails on a trivial derivation when __structuredAttrs is set.

Steps To Reproduce

Steps to reproduce the behaviour:

1. Build the following derivation:

runCommand "foo" {__structuredAttrs = true;} ''. .attrs.sh; mkdir ''${outputs[out]}''

and get this error

error: builder for '/nix/store/vj7a0vhacspbvfjyngqf12iq8gj9vagz-foo.drv' failed with exit code 1;
       last 1 log lines:
       > /nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25b-default-builder.sh: line 1: /setup: No such file or directory
       For full logs, run 'nix log /nix/store/vj7a0vhacspbvfjyngqf12iq8gj9vagz-foo.drv'.

Expected behavior

Derivation should build, akin to

runCommand "foo" {} ''mkdir $out''

Additional context

There is a partial workaround seen here where builder is set instead of buildCommand, however this leaves the utility functions defined in setup.sh unavailable to the builder.

Notify maintainers

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
output here

[abathur]

Idk why it would be the case, but the error itself sounds like the $stdenv var is empty when trying to run default-builder.sh:

nixpkgs/pkgs/stdenv/generic/default-builder.sh

Lines 1 to 6 in 92247c1

	if [ -f .attrs.sh ]; then
	. .attrs.sh
	fi
	source $stdenv/setup
	genericBuild

Not sure if this might be related to 238a605 or if that's a red herring.

[abathur]

I ended up here because someone reported a slightly different message on matrix (/nix/store/6xg259477c90a229xwmb53pdfkn6ig3g-default-builder.sh: line 6: genericBuild: command not found while rebuilding on NixOS) that sounds like it might also be caused by $stdenv being unset if errexit was enabled in the running script in your case but not in theirs.

That said, someone suggested that they try verifying the store, and they eventually reported that repairing the store solved the problem for then.

I suspect this means their case isn't actually related to the issue here, but I decided to document it just in case it helps connect dots later.

[Artturin]

Works for me

that error you're getting is from before structuredAttrs support was added, structuredAttrs currently only works on master/unstable.