Fix for infinite Ranges

.release-notes/4127.md

@@ -0,0 +1,13 @@
+## Fix for infinite Ranges
+
+Even though all Range objects that contain NaN parameters are considered infinite, some did not iterate at all or produced an error after the first iteration. For example, the code from the Range documentation: 
+
+```pony
+ // this Range will produce 0 at first, then infinitely NaN
+ let nan: F64 = F64(0) / F64(0)
+ for what_am_i in Range[F64](0, 1000, nan) do
+ wild_guess(what_am_i)
+ end 
+```
+
+did not run as expected, but rather produced an error on the first iteration. This is now fixed, and .next() calls on the above `Range[F64](0, 1000, nan)` now first yields 0 and subsequently indefinetely NaN values.

packages/collections/_test.pony

@@ -652,8 +652,6 @@ class \nodoc\ iso _TestRange is UnitTest
  _assert_infinite[F64](h, 0, 10, p_inf)
  _assert_infinite[F64](h, 100, 10, n_inf)
 
-
-
  fun _assert_infinite[N: (Real[N] val & Number)](
  h: TestHelper,
  min: N,
@@ -663,7 +661,18 @@ class \nodoc\ iso _TestRange is UnitTest
  let range: Range[N] = Range[N](min, max, step)
  let range_str = "Range(" + min.string() + ", " + max.string() + ", " + step.string() + ")"
 
- h.assert_true(range.is_infinite(), range_str + " should be infinite")
+ h.assert_true(range.is_infinite(), range_str + " should be infinite") 
+ try
+ let nextval = range.next()?
+ h.assert_eq[N](nextval, min)
+ else
+ h.fail(range_str + ".next(): first call should not fail but should produce " + min.string())
+ end
+ try
+ range.next()?
+ else
+ h.fail(range_str + ".next(): subsequent call should not fail")
+ end
 
  fun _assert_range[N: (Real[N] val & Number)](
  h: TestHelper,

packages/collections/range.pony

@@ -93,6 +93,9 @@ class Range[A: (Real[A] val & Number) = USize] is Iterator[A]
  or ((_min > _max) and (_inc > 0))
 
  fun has_next(): Bool =>
+ if _infinite then
+ return true
+ end
  if _forward then
  _idx < _max
  else