{.borrow:..} not working with distinct generics

[mratsim]

The following fails to compile

type Foo[T] = object
  foo: T

type Bar[T] {.borrow:`.`.} = distinct Foo[T]

[Vindaar]

Yep, just noticed that too.

[boyanl]

Sorry for the newbie question, but is there a way to work around this, apart from re-declaring accessors for the distinct type? (it's not too bad, but I'm wondering if there's something shorter)

[mratsim]

Working around type bugs is not a newbie question but an art. I use though mutable parameters requires some tricks with casts to raw addresses:

https://github.com/mratsim/trace-of-radiance/blob/99f7d85dec857f0efa0c9b0eafd339871599c0e1/trace_of_radiance/scenes_animated.nim#L71-L88

# workarounds https://github.com/nim-lang/Nim/issues/14440
# so ugly ...
func `+=`(a: var Distance, b: Distance) {.inline.}=
  cast[var float64](a.addr) += b.float64
func `-=`(a: var Velocity, b: Velocity) {.inline.}=
  cast[var float64](a.addr) -= b.float64

func `+=`(a: var ATime, b: ATime) {.inline.}=
  cast[var float32](a.addr) += b.float32
template `<`(a, b: ATime): bool =
  a.float32 < b.float32

template `*`(accel: Acceleration, dt: ATime): Velocity =
  Velocity(accel.float64 * dt.float64)
template `*`(v: Velocity, dt: ATime): Distance =
  Distance(v.float64 * dt.float64)
template `*`(k: float64, v: Velocity): Velocity =
  Velocity(k * v.float64)

[boyanl]

Thanks, but unless I'm missing a subtler point, it seem like it's a different issue?
I'll just do without the generic type for now, it's easy enough

[mratsim]

Ah right it was #14440, my bad. I created many distinct issues at that time.

[ringabout]

Related: #6039