Embedded templates with iterators fails to compile

[petermora]

The following code fails to compile. I'm wrapping templates with templates, and if the passed value is an iterator, then I get Error: illformed AST message.

# this compiles:
template t1(i: int): int=
  i+1
template t2(i: int): int=
  i+1

echo t1(10).t2()


# this doesn't:
template it1(i: int): iterator(): int =
  iterator result(): int {.closure, gensym.} =
    yield i+1
  result

template it2(iter: iterator(): int): iterator(): int =
  iterator result(): int {.closure, gensym.} =
    yield iter()+1
  result

let x = it1(10).it2()

If I save the intermediate result to a variable, then it compiles and runs fine:

let x = it1(10)
let y = x.it2()

[reactormonk]

The error is:

test.nim(12, 3) Error: illformed AST: iterator result(:envP): int {.closure, gensym.} = 
  goto :envP.:state
  state 0
  :envP.:state = 1
  return result = 11
  state 1
  :envP.:state = -1

:foo is a compiler-generated symbol.

The line with

  return result = 11

Most likely causes the issue - that's not valid nim.

[stale]

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[ringabout]

It compiles since Nim v 1.4.0.