Issue #8094 has been reported by jacknagel (Jack Nagel).

----------------------------------------
Bug #8094: Docs bug for Proc#arity
https://bugs.ruby-lang.org/issues/8094

Author: jacknagel (Jack Nagel)
Status: Open
Priority: Normal
Assignee: zzak (Zachary Scott)
Category: doc
Target version: 
ruby -v: ruby 2.0.0p0 (2013-02-24 revision 39474) [i386-darwin10.8.0]


The docs for Proc#arity in proc.c claim that
 
  proc { |x=0, y| }.arity # => 0

the result is really "1".



-- 
http://bugs.ruby-lang.org/