Stream: beginners

Topic: Compiler crash and hang

JRI98 (Dec 05 2023 at 17:07):

The following is a reduced case of a compiler crash and hang I encountered

app "a"
    packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.7.0/bkGby8jb0tmZYsy2hg1E_B2QrCgcSTxdUlHtETwm5m4.tar.br" }
    imports [pf.Stderr, pf.Task.{ Task }]
    provides [main] to pf

main =
    Task.ok {}
    |> Task.onErr \e ->
        dbg e
        Stderr.line ""

Error:

thread '<unnamed>' panicked at 'called `Option::unwrap()` on a `None` value', crates/compiler/mono/src/ir.rs:6152:56

Brendan Hansknecht (Dec 05 2023 at 17:18):

which command? does it hang with roc build and roc check?

JRI98 (Dec 05 2023 at 17:22):

Sorry, forgot to mention, it fails with roc build but passes roc check

Brendan Hansknecht (Dec 05 2023 at 17:28):

thread '<unnamed>' panicked at 'unspecialized lambda sets left over during resolution: LambdaSet([] + (<2171>FlexAble(*, [`Inspect.Inspect`]):`Inspect.toInspector`:2), ^<2174>), UlsOfVar(VecMap { keys: [2171], values: [VecSet { elements: [2170, 2173] }] })', crates/compiler/mono/src/layout.rs:2074:17

cc @Ayaz Hafiz in case he has any immediate ideas or comments around the issue in general. The error type here should be I32 due to the type of main in the platform.

JRI98 (Dec 05 2023 at 17:45):

We seem to be getting different errors :thinking:
(updated the initial message with the error)

Ayaz Hafiz (Dec 05 2023 at 18:20):

John I'm assuming you're running Roc via a release of the compiler? Brendan hit an earlier assertion in a debug version of the compiler, but the issue is the same

Ayaz Hafiz (Dec 05 2023 at 18:24):

I'm not 100% why this is happening. My guess is it's because the type wanted by the platform might not be visible at the time the app is specialized. If you explicitly annotate main here it should resolve that. I think we've discussed making that mandatory anyway.

Last updated: Jul 26 2025 at 12:14 UTC