Compiler expectation broken while playing with tutorial

[yasuiniko]

Error message

 % roc dev
An internal compiler expectation was broken.
This is definitely a compiler bug.
Please file an issue here: https://github.com/roc-lang/roc/issues/new/choose
thread 'main' panicked at 'region @17-49 not in list of dbgs', /Users/m1ci/actions-runner2/_work/roc/roc/crates/repl_expect/src/run.rs:521:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Device info

• M1 pro chip running macOS 14.0
• roc nightly pre-release, built from commit 849296a on Wed Nov 1 09:19:44 UTC 2023

Reproduction

The problem is caused by the dbg call on line 23 of the following code snippet, which I modified from the tutorial. I ran the code using roc dev.

## This is a comment for documentation, and includes a code block.
##
##     x = 2
##     expect x == 2
app "hello"
    packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.5.0/Cufzl36_SnJ4QbOoEmiJ5dIpUxBvdB3NEySvuH82Wio.tar.br" }
    imports [pf.Stdout]
    provides [main] to pf

birds = 3

iguanas = -2

total = birds + iguanas

isAre = pluralize "is" "are" total

animalS = pluralize "animal" "animals" total

totalCount = stringify total

pluralize = \singular, plural, count ->
    dbg Pluralize "'count' is: \(Num.toStr count)"

    if count == 1 then
        singular
    else
        plural

stringify = \num ->
    if num == 0 then
        "no"
    else if num < 0 then
        "negative"
    else
        Num.toStr num

main =
    Stdout.line "There \(isAre) \(totalCount) \(animalS).\n\(Num.toStr birds) birds and \(Num.toStr iguanas) iguanas."

[lukewilliamboswell]

Thank you for logging this issue @yasuiniko. I assume you figured out that if you remove the tag then it works correctly?

dbg can only accept 1 argument. Roc should provide a helpful error message. I suspect that #5775 will resolve this issue as this will be a function call and provide a helpful error message.

Below is a smaller repro.

 roc dev broken.roc
An internal compiler expectation was broken.
This is definitely a compiler bug.
Please file an issue here: https://github.com/roc-lang/roc/issues/new/choose
thread 'main' panicked at 'region @17-9 not in list of dbgs', /Users/luke/Documents/GitHub/roc/crates/repl_expect/src/run.rs:521:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

app "hello"
    packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.5.0/Cufzl36_SnJ4QbOoEmiJ5dIpUxBvdB3NEySvuH82Wio.tar.br" }
    imports [pf.Stdout]
    provides [main] to pf

foo : {} -> Str
foo = \_ ->
    dbg Tag ""
    
    "foo"

main = Stdout.line (foo {})

[yasuiniko]

Thanks for the quick response and advice!