[Python-projects] pylint false positive: Unused argument/variable on "-="

[Maarten ter Huurne]

Hi,

Another false positive. Again, I think it is new, but not 100% sure.

===
def exclude(setA, setB):
	setA -= setB
===
W0613:  1:exclude: Unused argument 'setA'

Or a variant with a local variable instead of an argument:
===
def exclude(func, setB):
	setA = func()
	setA -= setB
===
W0612:  2:exclude: Unused variable 'setA'

It seems that the left side of "-=" is not considered a use of the 
argument/variable.

The same message is issued for integers as for sets, but for sets a function 
like that can actually be useful while for integers it is not. So one could 
argue the message make sense for integers and other immutable types where 
the value is replaced rather than modified (such as "+=" for strings).
===
def subtract(numB):
	numA = 33
	numA -= numB
===
W0612:  2:subtract: Unused variable 'numA'

Bye,
		Maarten