A For-Next bug in 1.2.8-s682

[boriel]

No need to enforce a removal but I do not see much sense in keeping a
dynamic structure unless you want to shave off a one extra internal variable
and the code to manage it meaning certain limitations. If you want to be
really smart then the compiler could decide which loops would benefit
from a dynamic structure vs a static one, and instead of having two sets
of For-Next code in the compiler just do a branch based on a flag but that
could eat up the savings made so...

Hey, that's a much nicer idea instead:!: But could be difficult. At the moment, only constant expressions are detected as invariant code.
There's still much work to do in this area. Please, be patient.