T(a) not an L-value when a is an L-value and typeEqualsOrDistinct(T, typeof(a)) holds

[tersec]

Description

from std/typetraits import distinctBase

type
  V[p: static int] = distinct int
  D[p: static int] = distinct int
  T = V[1]

proc f(y: var T) = discard

var a: D[0]

static:
  doAssert distinctBase(T) is distinctBase(D[0])
  doAssert distinctBase(T) is int
  doAssert distinctBase(D[0]) is int
  doAssert T(a) is T

f(cast[ptr T](addr a)[])
f(T(a))

fails to build not for

f(cast[ptr T](addr a)[])

but rather for

f(T(a))

https://nim-lang.org/docs/manual.html#type-relations-convertible-relation states that

The type conversion T(a) is an L-value if a is an L-value and typeEqualsOrDistinct(T, typeof(a)) holds.
which is the case here.

Because a is an L-value here, and they're all ints per that static block, T(a) should therefore also be an L-value, but it appears not to be.

Nim Version

Nim Compiler Version 1.6.14 [Linux: amd64]
Compiled at 2023-06-29
Copyright (c) 2006-2023 by Andreas Rumpf

active boot switches: -d:release

Nim Compiler Version 2.0.1 [Linux: amd64]
Compiled at 2023-08-20
Copyright (c) 2006-2023 by Andreas Rumpf

git hash: 037f536e7ee25c4baf23dff8a4525825c506442c
active boot switches: -d:release

Nim Compiler Version 2.1.1 [Linux: amd64]
Compiled at 2023-08-20
Copyright (c) 2006-2023 by Andreas Rumpf

git hash: a4781dc4bcdf6e76076af80d0b21cb09865b3d44
active boot switches: -d:release

Current Output

r.nim(19, 2) Error: type mismatch
Expression: f(T(a))
  [1] T(a): T

Expected one of (first mismatch at [position]):
[1] proc f(y: var T)

Expected Output

No response

Possible Solution

No response

Additional Information

No response

[Araq]

+1 for quoting the spec.