Apply new attribute position semantics (name, not value)

[roberth]

Is your feature request related to a problem?

Some primops do not return attribute positions.
#13725 proposed to improve this for mapAttrs, implying that the attribute position is tied to the name; not the value.
Other primops and inherit don't make use of this rule yet.

Proposed solution

• zipAttrsWith
  • Fix getAttrPos after mapAttrs #13725 (comment)
• inherit?
  • Fix getAttrPos after mapAttrs #13725 (comment)

Alternative solutions

Tie it to the value, change #13725 to return the function body position, and do the same for zipAttrsWith.

Additional context

• flake: split into multiple files nixpkgs#433695 (comment)

Checklist

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

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[hsjobeki]

Regarding:

Tie it to the value, change #13725 to return the function body position, and do the same for zipAttrsWith.

Not sure how this affects current downstream users:

Currently a lot of things depend on getAttrPos pointing to the name.

• NixOS module system uses it for declaration positions (mergeModules')
• callPackageWith: uses for error reporting
• lib docs: use them for finding the function location

The proposed alternative would probably introduce a lot of regressions / behavior change