buildEnv: allow custom environment variables to be set

[adnelson]

Motivation for this change

buildEnv allows for a postBuild step, but doesn't provide a mechanism for setting environment variables during that step besides inlining them into the bash string (which could have problems e.g. with special characters). This adds an environment parameter which allows environment variables to be set.

Things done

Not really anything to test here; none of the existing libraries use this. I've build envs of my own using this parameter, and it works.

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

---

[mention-bot]

@adnelson, thanks for your PR! By analyzing the history of the files in this pull request, we identified @vcunat, @aszlig and @edolstra to be potential reviewers.

[danbst]

The commit is authored by 'Test'. Is that intentional? :)

[adnelson]

@danbst Whoops, not sure how that happened...

[adnelson]

@edolstra This has been sitting here for a while, any chance it could get merged?

[matthewbauer]

/cc @Mic92 bump?

[matthewbauer]

One thing to note is that you can do away with passthru, meta, and buildInputs once you have this (for the arguments to buildEnv).

[mmahut]

@adnelson @Mic92 Any update on this pull request?

[Mic92]

@GrahamcOfBorg eval

[mmahut]

@Mic92 do you wish to keep this open?

[stale]

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[L-as]

I don't think this is useful, since you can do what you want by just doing overrideAttrs on the buildEnv derivation then adding your postBuild and all necessary environment variables there.

I'm in favor of closing this.

[roberth]

In addition to @L-as, for consistency we'd have to allow this everywhere, which is not feasible and not necessary.