feat(tvix/eval): implement tvix's user-agent, err, nixVersion

nixpkgs has hardcoded references to Nix versions, we need to provide
it with something that looks like a Nix version while actually being a
Tvix version.

For now, we do this by stealing a trick out of the browser book and
constructing a version that looks like a Nix version to Nix, but like
a Tvix version to people who know what they are looking for.

Nevermind that we don't actually have any kind of versioning for
Tvix (yet?), other than depot revisions.

Change-Id: I7ce8079dd8164a2079891d38e707f09a45f0bbc1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6858
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2022-10-04 18:40:57 +03:00 committed by tazjin
parent 8f2c67d5dd
commit 7fe1331570
3 changed files with 12 additions and 0 deletions

View file

@ -374,6 +374,12 @@ fn pure_builtins() -> Vec<Builtin> {
fn builtins_set() -> NixAttrs {
let mut map: BTreeMap<NixString, Value> = BTreeMap::new();
// Pure-value builtins
map.insert(
"nixVersion".into(),
Value::String("2.3-compat-tvix-0.1".into()),
);
let mut add_builtins = |builtins: Vec<Builtin>| {
for builtin in builtins {
map.insert(builtin.name().into(), Value::Builtin(builtin));

View file

@ -0,0 +1 @@
-1

View file

@ -0,0 +1,5 @@
# nixpkgs checks against the `builtins.nixVersion` and fails if it
# doesn't like what it sees. To work around this we have a "user-agent
# style" version (see cl/6858) that ensures compatibility.
builtins.compareVersions "2.3" builtins.nixVersion