Agus Zubiaga (Mar 24 2023 at 02:18): Agus Zubiaga (Mar 24 2023 at 02:18):If you use dbg in a package's interface file, the compiler throws the following error and hangs:
Thread '<unnamed>' panicked at 'called `Option::unwrap()` on a `None` value', crates/compiler/mono/src/ir.rs:6826:18
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Apparently, env.expectation_subs is None here: https://github.com/roc-lang/roc/blob/24e2c661870d9d7c54a5aa8750c334a837af1966/crates/compiler/mono/src/ir.rs#L6808-L6812
Brendan Hansknecht (Mar 24 2023 at 02:28):I wonder if that is interface specific. I have seen similar errors a lot. That and sometimes debug just not printing. Definitely one of the easier to break features. I think i notice it most in rather nested code, especially if related to tasks.
Agus Zubiaga (Mar 24 2023 at 02:32):Oh. I haven't noticed that. In this case the app's main is directly calling the function from the package's interface with the dbg usage in it.
Brendan Hansknecht (Mar 24 2023 at 02:52):At least in my absolute minimal repro, it is working in an interface:
interface Interface
exposes [someFunc]
imports []
someFunc = \x ->
dbg x
x
So maybe not interface specific. Are you able to share example code where this happens or a repro?
Brendan Hansknecht (Mar 24 2023 at 02:59):Oh, nevermind, I can repro.
Brendan Hansknecht (Mar 24 2023 at 03:00):It takes an interface in a package specifically, not an interface in general.
Brendan Hansknecht (Mar 24 2023 at 03:05):submitted #5185 as a minimal repro.
Agus Zubiaga (Mar 24 2023 at 03:47):Nice
Agus Zubiaga (Mar 24 2023 at 04:00):Found the root cause of the None in env.expectaction_subs: https://github.com/roc-lang/roc/blob/24e2c661870d9d7c54a5aa8750c334a837af1966/crates/compiler/load_internal/src/file.rs#L2748-L2753
let should_include_expects = (!loc_expects.is_empty() || !loc_dbgs.is_empty()) && {
let modules = state.arc_modules.lock();
modules
.package_eq(module_id, state.root_id)
.expect("root or this module is not yet known - that's a bug!")
};
!loc_dbgs.is_empty() is true because the dbg exists
Agus Zubiaga (Mar 24 2023 at 04:02):but .package_eq(module_id, state.root_id) evaluates to false because the module is in a different package
Agus Zubiaga (Mar 24 2023 at 04:04):When building applications, you probably don't want to include expects from packages, so that makes sense
Agus Zubiaga (Mar 24 2023 at 04:05):However, we still need a way to use dbg and expect when building packages. Maybe this can be a CLI option?
Agus Zubiaga (Mar 24 2023 at 04:08):Also, in normal operation, it shouldn't crash because a package contains a dbg or expect
Richard Feldman (Mar 24 2023 at 20:37):this is an interesting design question...I've gone back and forth on this in the past, but what makes sense to me right now is:
dbg no matter where it comes from. This way if you're debugging a local package on your filesystem, it Just Works.dbg (just take them out before you publish, don't annoy people with your own debugging logic!) Richard Feldman (Mar 24 2023 at 20:37):expect is trickier because on the one hand it could be annoying if I get a third-party package that's crashing due to failed expects all the time...but on the other hand, wouldn't it be better if I could report that to them? :thinking:
Richard Feldman (Mar 24 2023 at 20:38):my default thinking is that expect should just always work the same way no matter whether it's a package, and then we can revisit that if it's annoying in practice
Agus Zubiaga (Mar 24 2023 at 21:08):Ah cool. So we just need to get rid of that package_eq check, then.
Agus Zubiaga (Mar 24 2023 at 21:09):I tried it last night and dbg just started working from packages
Agus Zubiaga (Mar 24 2023 at 21:10):Should I make a PR with that change?
Richard Feldman (Mar 24 2023 at 21:19):sounds good to me! @Folkert de Vries any concerns?
Ayaz Hafiz (Mar 24 2023 at 21:21):The one annoyance with this is that this will also mean “roc test” will run all tests under a package and all its dependencies, not just local to the module.
Ayaz Hafiz (Mar 24 2023 at 21:22):That could be made into a separate check though
Richard Feldman (Mar 24 2023 at 21:56):hm, aren't those separate?
Richard Feldman (Mar 24 2023 at 21:56):like roc test doesn't have to run top-level expects in other packages
Richard Feldman (Mar 24 2023 at 21:56):even if it still runs inline expects
Ayaz Hafiz (Mar 24 2023 at 22:19):Right. I just mean that the implementation, I don't think it is enough to only get rid of the package_eq check.
Agus Zubiaga (Mar 24 2023 at 22:20):Yeah, if I get rid of that check, roc test includes expects from packages
Agus Zubiaga (Mar 24 2023 at 22:21):and this weird bug shows up if I have both dbgs and expects in a package, roc test hangs, but it works fine if only have one kind :oh_no:
Richard Feldman (Mar 25 2023 at 00:43):Agus Zubiaga said:
Yeah, if I get rid of that check,
roc testincludesexpects from packages
oh ok, so then the problem is that right after that code we're using should_include_expects to decide whether to include dbgs too
Richard Feldman (Mar 25 2023 at 00:43): Richard Feldman (Mar 25 2023 at 00:43):so that line could be used in the else branch too, just with expectations: being empty
Richard Feldman (Mar 25 2023 at 00:44):could go even further to have that under an else if !loc_dbgs.is_empty() { so we don't bother cloning solved_subs etc if there happen to be no dbgs
Last updated: Jul 26 2025 at 12:14 UTC