Bug #19349: Kernel.Integer silently discards base argument that does not have a #to_int

• Status: Open
• Priority: Normal
• Assignee: -
• Target version: -
• ruby -v: ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux-gnu]
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

[herwin (Herwin W)]

The method Kernel.Integer has an optional argument base, which is the base to convert the input to:

irb(main):001:0> Kernel.Integer('10', 8)
=> 8

If the base argument is not an integer, it is converted using #to_int

irb(main):002:0> Kernel.Integer('10', 8.2)
=> 8
irb(main):003:0> Kernel.Integer('10', Object.new.tap { |x| x.define_singleton_method(:to_int) { 8 } })
=> 8

But if the base argument is not an Integer, and does not have a #to_int method, it gets discarded

irb(main):004:0> Kernel.Integer('10', '8')
=> 10

I would expect this to raise a TypeError, similar to String#to_i:

irb(main):005:0> '10'.to_i('8')
(irb):5:in `to_i': no implicit conversion of String into Integer (TypeError)

This has briefly been discussed on the ruby-spec github repo, and they suggested to report this as a bug. (see https://github.com/ruby/spec/pull/997#issuecomment-1382825900)

[herwin (Herwin W)]

And likely related: in case the output of the call to to_int returns something that is not an integer, it gets discarded as well

Kernel.Integer('10', Object.new.tap { |x| x.define_singleton_method(:to_int) { '8' } })
=> 10

[nobu (Nobuyoshi Nakada)]

https://github.com/ruby/ruby/pull/7144