panic on recursive functions · beginners

app [main] {
    pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.10.0/vNe6s9hWzoTZtFmNkvEICPErI9ptji_ySjicO6CkucY.tar.br",
}

import pf.Stdout
import pf.Task

displayBlock = \{ widget ? None } ->
    when widget is
        None -> "{}"
        w -> "{ $(displayWidget w) }"

displayGroup = \group ->
    "[$(group.widgets |> List.map displayWidget |> Str.joinWith ", ")]"

displayWidget = \widget ->
    when widget is
        Block block -> "block $(displayBlock block)"
        Group group -> "group $(displayGroup group)"
        None -> ""

main =
    # works
    Stdout.line! (displayWidget (Block {}))
    Stdout.line! (displayWidget (Group { widgets: [] }))
    Stdout.line! (displayWidget (Block { widget: Group { widgets: [] } }))
    # fails with panic
    Stdout.line! (displayWidget (Block { widget: Block {} }))

thread 'main' panicked at crates/compiler/gen_llvm/src/llvm/build.rs:5764:19:
Error in alias analysis: error in module ModName("UserApp"), function definition FuncName("\x11\x00\x00\x00\x11\x00\x00\x00\xb4e[-\xa6\x8d\x12P"), definition of value binding ValueId(4): expected type '("UserApp"::"\xbf\xb4\xe0\xb0\xed\x84F\x9d",)', found type '((),)'
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Brendan Hansknecht (Jun 18 2024 at 20:48):

I think the compiler is confused trying to figure out the types and you have a bug with type definitions

Brendan Hansknecht (Jun 18 2024 at 20:49):

Brendan Hansknecht (Jun 18 2024 at 20:50):

Cause a block takes a record that contains a widget, but the inner block is taking an empty record

Brendan Hansknecht (Jun 18 2024 at 20:51):

That said, the types in this program are extra strange. I think that the compiler is generating two different versions of Block, but they can't be used together.

Brendan Hansknecht (Jun 18 2024 at 20:54):

I would try to explictly write out the types, I think that will reveal the issues.

Widget : [
  Block {widget: Widget},
  Group (List Widget),
  None
]

Brendan Hansknecht (Jun 18 2024 at 20:56):

    Stdout.line! (displayWidget (Block {}))
    Stdout.line! (displayWidget (Block { widget: Group { widgets: [] } }))

Brendan Hansknecht (Jun 18 2024 at 20:58):

Looking at the ir, this compiles cause roc is generating two distinct versions of displayWidget that accept different types.

Brendan Hansknecht (Jun 18 2024 at 20:59):

Ghislain (Jun 18 2024 at 21:05):

Thank you for your reply, I tried with your type (a bit modified to have a record) and I get compiler issue this time:

app [main] {
    pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.10.0/vNe6s9hWzoTZtFmNkvEICPErI9ptji_ySjicO6CkucY.tar.br",
}

import pf.Stdout
import pf.Task

Widget : [
    Block { widget : Widget },
    Group { widgets : List Widget },
    None,
]

displayBlock = \{ widget } ->
    when widget is
        None -> "{}"
        w -> "{ $(displayWidget w) }"

displayGroup = \group ->
    "[$(group.widgets |> List.map displayWidget |> Str.joinWith ", ")]"

displayWidget : Widget -> Str
displayWidget = \widget ->
    when widget is
        Block block -> "block $(displayBlock block)"
        Group group -> "group $(displayGroup group)"
        None -> "unknown"

main =
    Stdout.line! (displayWidget (Block { widget: None }))

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 '<unnamed>' panicked at crates/compiler/mono/src/layout.rs:1589:17:
no lambda set found for (`17.IdentId(4)`, []): LambdaSet {
    set: [],
    args: [
        InLayout(
            91,
        ),
    ],
    ret: InLayout(STR),
    representation: InLayout(VOID),
    full_layout: InLayout(
        103,
    ),
}
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Stream: beginners

Topic: panic on recursive functions

Ghislain (Jun 18 2024 at 20:16):