The following code (and yes, this is just an example and not good Ruby code) pattern:
x = 10
for i in 1..10
@z = x
x *= 10 if @z < 10000
Will indicate (by underlining) that x within the statement "x *= 10 if @z < 10000" in no longer used.
If you remove the conditional "if @z < 10000" then it's OK---it understands that x is used within the for loop. But put the conditional on it and you get the warning.
I'm using EAP RM-93.130