Can't nest loops even when only one of them is unrolled

[schneiderfelipe]

This affects these examples, for instance

unrolled/tests/tests.nim

Lines 48 to 79 in a18ab5a

	# BUG: !!!
	# suite "Nested for-loops over slices":
	# test "unroll works in inner nested loops":
	# expandMacros:
	# var total: int
	# for i in 1..3:
	# unroll for j in 1..3:
	# total += i + j
	# check total == (1 + 1) + (1 + 2) + (1 + 3) +
	# (2 + 1) + (2 + 2) + (2 + 3) +
	# (3 + 1) + (3 + 2) + (3 + 3)
	# test "unroll works in outer nested loops":
	# expandMacros:
	# var total: int
	# unroll for i in 1..3:
	# for j in 1..3:
	# total += i + j
	# check total == (1 + 1) + (1 + 2) + (1 + 3) +
	# (2 + 1) + (2 + 2) + (2 + 3) +
	# (3 + 1) + (3 + 2) + (3 + 3)
	# test "unroll works with multiple nested loops":
	# expandMacros:
	# var total: int
	# unroll:
	# for i in 1..3:
	# for j in 1..3:
	# total += i + j
	# check total == (1 + 1) + (1 + 2) + (1 + 3) +
	# (2 + 1) + (2 + 2) + (2 + 3) +
	# (3 + 1) + (3 + 2) + (3 + 3)

Again (see #1), all three tests pass if we accept an untyped parameter in

unrolled/src/unrolled.nim

Lines 117 to 118 in a18ab5a

	macro unroll*(x: typed): auto =
	## Unroll for-loops.

Below the expanded code for the first example:

var total: int
block:
  for j in 1 .. 3:
    total += 1 + j
block:
  for j in 1 .. 3:
    total += 2 + j
block:
  for j in 1 .. 3:
    total += 3 + j