Strange sizeof behaviour depending on calling syntax

[mratsim]

This works (on devel, not on 0.17.2)

type ByteArrayBE*[N: static[int]] = array[N, byte]
  ## A byte array that stores bytes in big-endian order

proc toByteArrayBE*[T: SomeInteger](num: T): ByteArrayBE[T.sizeof]=
  ## Convert an integer (in native host endianness) to a big-endian byte array
  const N = T.sizeof
  for i in 0 ..< N:
    result[i] = byte(num shr ((N-1-i) * 8))

let a = 12345.toByteArrayBE

echo a # [0, 0, 0, 0, 0, 0, 48, 57]

Now if I change T.sizeof to sizeof(T) in the result type I get Error: cannot evaluate 'sizeof' because type is not defined completely

type ByteArrayBE*[N: static[int]] = array[N, byte]
  ## A byte array that stores bytes in big-endian order

proc toByteArrayBE*[T: SomeInteger](num: T): ByteArrayBE[sizeof(T)]=
  ## Convert an integer (in native host endianness) to a big-endian byte array
  ## Notice the result type
  const N = T.sizeof
  for i in 0 ..< N:
    result[i] = byte(num shr ((N-1-i) * 8))

let a = 12345.toByteArrayBE

echo a

[LemonBoy]

The failing snippet hits this spot while the working one is not affected due to how the nkDotExp is const-folded.

I think that if computeSize returns szUnknownSize it's safe not to raise an error, what do you think @Araq?

[Araq]

semfold must not kick in for "in flux" dot calls that will be rewritten as f(x).

[LemonBoy]

paramTypesMatchAux tries to fold the ByteArrayBE[sizeof(T)] argument during the sigmatch via semTryConstExpr here (a.kind is tyInt here)

[narimiran]

Both examples work in Nim 0.19.9