Profile list improvements

[iFreilicht]

Motivation

PR #6481 has been ready to merge for over a year now, but became outdated and can't be merged due to conflicts. This PR is basically a rebase of that old PR on the current master so that it can be merged.

Context

See PR #6481 for details.

Checklist for maintainers

Maintainers: tick if completed or explain if not relevant

• agreed on idea
• agreed on implementation strategy
• tests, as appropriate
  • functional tests - tests/**.sh
  • unit tests - src/*/tests
  • integration tests - tests/nixos/*
• documentation in the manual
• documentation in the internal API docs
• code and comments are self-explanatory
• commit message explains why the change was made
• new feature or incompatible change: updated release notes

Priorities

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[edolstra]

Looks good.

I wonder if we should change "index" to something like "position" or "number".

[iFreilicht]

@edolstra I think index is fine right now, but I see what you mean. I would be more in favor of actually replacing them with proper names, though, see #7967.

[edolstra]

This appears to have broken the coverage job: https://hydra.nixos.org/build/226443887

    libgcov profiling error:/build/source/src/build-remote/build-remote.gcda:Merge mismatch for function 1619
...
    nix-profile.sh: test failed at:
      main in nix-profile.sh:145

[iFreilicht]

Huh, I wanted to fix that, but I can't even reproduce this. The job you linked says that the build of /nix/store/b27f2q6f4qf4ff306fh8m69ij59qrmf6-nix-coverage-2.17.0pre20230705_6db66eb failed, but I produced that exact store path locally without an issue:

$ git show HEAD --oneline
6db66ebfc (HEAD -> nix-fix-broken-coverage, fix-broken-coverage) Merge pull request #8631 from iFreilicht/profile-list
$ nix build .#hydraJobs.coverage
$ readlink result
/nix/store/b27f2q6f4qf4ff306fh8m69ij59qrmf6-nix-coverage-2.17.0pre20230705_6db66eb
$ nix-store -l /nix/store/b27f2q6f4qf4ff306fh8m69ij59qrmf6-nix-coverage-2.17.0pre20230705_6db66eb | grep -B 1 -A 3 nix-profile.sh
  CXX    tests/test-libstoreconsumer/main.o
  GEN    scripts/nix-profile.sh
  GEN    doc/manual/nix-env.1
  GEN    doc/manual/nix-store.1
  GEN    doc/manual/nix-shell.1
--
ran test tests/build-delete.sh... [PASS]
ran test tests/nix-profile.sh... [PASS]
installCheckPhase completed in 2 minutes 5 seconds
@nix { "action": "setPhase", "phase": "finalPhase" }
finalPhase

How could this possibly happen?