Rename "input path"

[edolstra]

Describe the bug

The "input path" terminology is confusing because they're not paths (i.e. SourcePaths or file system paths), they're sequences of attribute names (like dwarffs.nixpkgs) denoting a traversal through the flake input graph.

Suggestions:

• Input chain
• Input attribute path
• ...

Steps To Reproduce

Expected behavior

Metadata

Additional context

Checklist

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

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[abathur]

It isn't a top-level definition of its own, but the doc entry for the attribute selection operator does already define an attribute path or attrpath as a dot-separated list of attribute names.

https://nix.dev/manual/nix/2.23/language/operators#attribute-selection

If attrpath were promoted to a readily linkable term somewhere, it might suffice to change from "input path" to "input attrpath"?