new-styled concepts: type mismatch for function implemented for other generic concept

[pacien]

Nim Version

Nim Compiler Version 2.2.2 [Linux: amd64]
Linux 6.6.56, NixOS 24.11

Description

I'm attempting to define a concept using a function implemented for another generic concept.
The following example compiles with old-styled concepts, but fails with new-styled concepts:

test.nim:

type Indexable[T] = concept
  proc `[]`(t: Self, i: int): T
  proc len(t: Self): int

iterator items[T](t: Indexable[T]): T =
  for i in 0 ..< t.len:
    yield t[i]


# With new-styled concepts: type mismatch
type Enumerable[T] = concept
  iterator items(t: Self): T

# With old-styled concepts: works
# type Enumerable[T] = concept c
#   items(c) is T

proc echoAll[T](t: Enumerable[T]) =
  for item in t:
    echo item


type DummyIndexable[T] = distinct seq[T]

proc `[]`[T](t: DummyIndexable[T], i: int): T =
  seq[T](t)[i]

proc len[T](t: DummyIndexable[T]): int =
  seq[T](t).len


let dummyIndexable = DummyIndexable(@[1, 2])
echoAll(dummyIndexable)

Current Output

test.nim(33, 8) Error: type mismatch
Expression: echoAll(dummyIndexable)
  [1] dummyIndexable: DummyIndexable[system.int]

Expected one of (first mismatch at [position]):
[1] proc echoAll[T](t: Enumerable[T])

Expected Output

1
2

Known Workarounds

Using old-styled concepts (as commented in the example snippet) works.

Additional Information

No response