Command line attribute rev is ignored

[nlewo]

The rev attribute is ignored when provided on CLI.

Considering niv add NixOS/nixpkgs -a rev=plop, the sources.json should contains rev=plop while rev have been updated according to the --branch attribute.

Specifying a rev attribute is useful when switching a project to Niv because it allows to introduce Niv without changing what is actually built.

[nmattia]

Indeed, this should be whenNotSet :

niv/Main.hs

Line 239 in c2698b0

setPackageSpecAttr "rev" (Aeson.String rev)

Nice catch! Will patch soon.

[michaelpj]

It's a little more awkward than that. This is the bit that actually makes niv update do an update! I think that:

• completePackageSpec should not update the rev (i.e. should use whenNotSet
• We should have some other updatePackageSpec function that we use instead of completePackageSpec in cmdUpdate

[michaelpj]

It would also be nice if niv update -a rev=<blob> would update to that revision, whereas currently it just updates to the latest regardless.

[nmattia]

This issue actually led me down a terribly deep rabbit hole: https://github.com/nmattia/niv/compare/nm-refactor (which is also aimed at making #35 nicer and hence blocking it). Hoping to find some time to finish things up soon... Worst case, Zurihac.