BUG: can't refer to generic type in return type

[timotheecour]

reduced a bit from PR #8531 where I'm forced to using auto return instead of explicit type

seems related but not same as #8545

# BUG: can't refer to generic type in return type
import macros

macro distinctBase2*(T: typedesc): untyped =
  let typeNode = getTypeImpl(T)
  expectKind(typeNode, nnkBracketExpr)
  if typeNode[0].typeKind != ntyTypeDesc:
    error "expected typeDesc, got " & $typeNode[0]
  var typeSym = typeNode[1]

  typeSym = getTypeImpl(typeSym)

  echo typeSym.treeRepr # Sym "T"

  if typeSym.typeKind != ntyDistinct:
    error "type is not distinct: " & $typeSym.typeKind

  typeSym = typeSym[0]
  typeSym

when defined(case1):
  # ok
  func distinctBase*[T](a: T): auto = distinctBase2(T)(a)
when defined(case2):
  # Error: type is not distinct: ntyGenericParam
  func distinctBase*[T](a: T): distinctBase2(T) = distinctBase2(T)(a)

when isMainModule:
  type T=distinct int
  discard distinctBase(T(0))

[mratsim]

Link to RFC nim-lang/RFCs#44

[metagn]

Early generic evaluation bug again, delegating to type works because it's a macro call which is delayed

import typetraits

type DistinctBase[T] = distinctBase(T)
func distinctBase*[T](a: T): DistinctBase[T] = distinctBase(T)(a)

type T = distinct int
discard distinctBase(T(0))

Tons of issues are related but I can only link #22607 right now