Compiler hang

[Janiczek]

I got this compiler hang when working on my solution for an Advent of Code puzzle.

roc --version
roc nightly pre-release, built from commit e65f14fa496 on Sat Dec  2 09:15:51 UTC 2023

Shrunk it down to this SSCCE.

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

main = 
    Stdout.line "Hello, world!"

a : Str -> Set (Nat,Nat,Str)
a = \_ -> Set.empty {}

expect a "" == Set.fromList []

b : Set (Nat,Nat,Str) -> Set (Nat,Nat)
b = \_ -> Set.empty {}

expect b (Set.fromList []) == Set.fromList [(0,0,"")]

Try roc run or roc test or some other command, and the compiler gets stuck in some infinite loop.

[skyqrose]

I think this was probably fixed by #6792

[JRI98]

Still reproduces on Apple silicon:

app [main] { pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.15.0/SlwdbJ-3GR7uBWQo6zlmYWNYOxnvo8r6YABXD-45UOw.tar.br" }

main =
    crash ""

a : Str -> Set (U64, U64, Str)
a = \_ -> Set.empty {}

expect a "" == Set.fromList []

b : Set (U64, U64, Str) -> Set (U64, U64)
b = \_ -> Set.empty {}

expect b (Set.fromList []) == Set.fromList [(0, 0, "")]