Re: reference-scanning inputDrvs/inputSrcs

[Vincent Ambo <tazjin@tvl.su>]

On 1/10/23 23:20, Adam Joseph wrote:
> If I don't get it exactly right on the first try, tvix will get the blame
> for any behavioral differences, and that is not cool.

I think we have thick enough skin to deal with this ;) My plan is to go 
ahead anyways and implement this string-scanning based solution. We're 
fairly close to producing arbitrary derivation hashes, and as we're 
serialising derivations into the same format as C++ Nix we'll be able to 
use existing diff tools to figure out discrepancies when computing 
hashes over the whole package set.

I think this will allow us to figure out problems quite quickly! We can 
always resort to implementing string contexts if necessary.

> The implementation is straightforward and obvious except for placeholder > and unsafeDiscardOutputDependency

placeholders should fit into how we're envisioning the rest of the 
machinery pretty well, we'll see.

context discarding builtins are interesting, I have a working theory 
that the use-cases in which they are currently used simply do not apply 
in Tvix (and we can implement them as no-ops that emit warnings), and 
will probably write up another post about that.

> I have been dragged into a really enormous project that I have been wanting
> to do for a long time:
>
>    https://github.com/NixOS/nixpkgs/pull/209870

Cool to see work on bootstrap infrastructure. Hoping we can (in the not 
so far future) also collaborate with the Guix folks on that ...
Good luck with the project!

//V