[ruby-core:83906] [Ruby trunk Feature#13763] Trigger "unused variable warning" for unused variables in parameter lists

Issue #13763 has been updated by marcandre (Marc-Andre Lafortune).


Hanmac (Hans Mackowiak) wrote:
> i am against this, becauese such functions could be used as hookups too for other functions to overwrite them.

This is particularly true for named parameters, which can not be renamed with a leading underscore.

FWIW, `rubocop` can detect those already, for any version of Ruby, and is customizable by the user.

I feel that it's probably best to handle such cases at a higher level than MRI itself.

----------------------------------------
Feature #13763: Trigger "unused variable warning" for unused variables in parameter lists
https://bugs.ruby-lang.org/issues/13763#change-67956

* Author: rovf (Ronald Fischer)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
Consider the following program nowa.rb:

~~~
def foo(a)
end
%w(x).each {|y|}
foo(1)
z=5
~~~

If I syntax-check it with *ruby -cw nowa.rb* I get the following warning:

~~~
nowa.rb:5: warning: assigned but unused variable - z
~~~

Ruby complains about z, but does not complain about a and y, even though these are also variables which receive a value which never is used. I suggest to issue a warning in these cases too.

Tested with: ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-cygwin]



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