Attribute paths with --arg and --argstr

[Ericson2314]

Nix CLIs should support --arg and --argstr flags with paths containing more than one attribute.

The semantics of --arg and --argstr are a bit complicated (perhaps over-complicated, but that's another issue, CC @cleverca22), so I will specify via desugaring:

1. --argstr <single-attr> 'foo' becomes --arg <single-attr> '"foo"' just like today.
2. --arg some-attr.remaining0 expr0 ...--arg some-attr.remainingN experN becomes --arg some-attr '{ remaining0 = expr0; ...remainingN = exprN; }'
3. (Multiple-attribute remainingN in the attribute set are similarly decomposed and grouped just like today.)

This fills in what's IMO an awkward gap in the CLI, but also is important for making cross compilation more ergonomic.

CC @dtzWill

[lheckemann]

I think you meant @cleverca22 ?

[Ericson2314]

Ah yeah. Thanks.

[stale]

I marked this as stale due to inactivity. → More info