build(nix): Fix Nix grammars build due to breaking changes in fetchTree

[mstrangfeld]

Due to NixOS/nix@09d76e5
Fixes issue #9866

This is the easiest fix for now. We maybe should consider prefetching the GitHub repos and calculate the NAR hashes but this would be an extra step that cannot be integrated into the pure build evaluation.

[the-mikedavis]

IIRC we special-cased github grammars because the github fetcher was much much faster than the git fetcher. (I believe it's getting a tarball of the exact revision rather than cloning, or something like that.) So this is an unfortunate breakage from Nix. Hopefully the caching from cachix will make the build fast enough.

I left a comment about refs but otherwise this looks good

[the-mikedavis]

The nix build fails for me on this branch with Nix 2.18.1. A few grammars in languages.toml use commits that aren't from their HEAD, for example tree-sitter-groovy is from the gh-pages branch:

error:
       … while calling the 'derivationStrict' builtin

         at /builtin/derivation.nix:9:12: (source not available)

       … while evaluating derivation 'helix-term-23.10.0'
         whose name attribute is located at /nix/store/bjvqq8c79dbi59g7xzcc6lhl0f19m3d7-source/pkgs/stdenv/generic/make-derivation.nix:353:7

       … while evaluating attribute 'buildCommand' of derivation 'helix-term-23.10.0'

         at /nix/store/bjvqq8c79dbi59g7xzcc6lhl0f19m3d7-source/pkgs/build-support/trivial-builders/default.nix:98:16:

           97|         enableParallelBuilding = true;
           98|         inherit buildCommand name;
             |                ^
           99|         passAsFile = [ "buildCommand" ]

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: Cannot find Git revision '7e023227f46fee428b16a0288eeb0f65ee2523ec' in ref 'HEAD' of repository 'https://github.com/Decodetalkers/tree-sitter-groovy'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.

I believe this needs to be

Suggested change

	ref = grammar.source.ref or "HEAD";
	allRefs = true;

instead, or we need to add ref to all grammars that don't use their main branch for committing tree-sitter outputs. (We should use allRefs instead because not all language-support contributors use Nix so they won't know to update the ref.)

[archseer]

Could we add the NAR hashes in a separate lock file? Seems like a big regression if we switch over to fetchGit