Bug #7837: IO.open with three arguments where third argument is bogus reports an arity problem instead of type problem

• Status: Rejected
• Assignee: -
• Target version: 2.6
• ruby -v: ruby 2.0.0dev (2013-02-08 trunk 39161) [x86_64-darwin11.4.2]

[enebo (Thomas Enebo)]

I am reporting this against 2.0.rc2 but it also applies to mri 1.9.3. If I run the following one-liner:

mri20 -e 'f = File.open("tmp"); IO.open(f.fileno, "r", :heh)'

I get the error:

-e:1:in `initialize': wrong number of arguments (3 for 1..2) (ArgumentError)

This seems wrong because if I change the third argument to an options hash it works fine. So having an arity of 3 is not a problem for open. It is that :heh is not a hash. I think this should generate a TypeError.

[drbrain (Eric Hodel)]

• Category set to core
• Target version set to 2.6

=begin
Since Ruby 1.9.3p374 has the same behavior I have marked this for next minor:

$ ruby19 -ve 'f = File.open("tmp"); IO.open(f.fileno, "r", :heh)'
ruby 1.9.3p374 (2013-01-15 revision 38858) [x86_64-darwin12.2.1]
-e:1:in initialize': wrong number of arguments (3 for 1..2) (ArgumentError) from -e:1:in open'
from -e:1:in `'

=end

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Rejected

=begin
It's common behavior to keyword arguments,

$ ruby -e 'def foo(a, b, c:1);end' -e 'foo(2,3,42)'
-e:1:in foo': wrong number of arguments (3 for 2) (ArgumentError) from -e:2:in '

The optional argument hash is stripped before arity check, so it's "invisible" as arity.
=end