fetchTarball and implicit dependencies on tar and gzip?

[copumpkin]

I haven't tied down a proper reproduction yet, but a friend of mine reported that fetchTarball complained about a missing tar and gzip dependency when he tried using it, which seems like a known issue from here.

cc @edolstra

[copumpkin]

It looks like we'll have similar issues with git and https://github.com/NixOS/nix/blob/master/src/libexpr/primops/fetchgit.cc.

[Shou]

The work done in #2498 might be generally relevant here

[FRidh]

related #2419

[vcunat]

If these properties remain, they should certainly be documented in https://nixos.org/nix/manual/#ssec-builtins

Another possible approach: nix already has a runtime dependency on a minimalistic busybox for the sandbox shell, so we might just build it with a couple more utilities and use those instead of $PATH. Quick test: ATM it has du size 160k, and adding CONFIG_TAR y only bumped it to 176k (including space for one extra symlink).

[edolstra]

The dependency on tar is removed by #2748 (especially 5351f1b).

[3noch]

Can this be closed then?

[edolstra]

Yes, thanks!