[ruby-core:119102] [Ruby master Bug#20716] Different instance_method behavior in Ruby 2.7 and Ruby 3.x

9 Sep 2024

      Issue #20716 has been updated by jeremyevans0 (Jeremy Evans).

natton (Tien Truong) wrote in #note-4:
...
I am new here so is there anything I can do to escalate this or how can I help to resolve this issue?
There isn't an escalation process in place in Ruby, as it is an open source project managed by volunteers.  In terms of helping to resolve the issue, first, we need to determine the cause of the bug.  Bisecting changes between 2.7 and 3.0 would help here to confirm the actual commit that caused the issue (the commit I listed in  an early comment is just a guess). I tried bisecting myself, but I think the current version of bison doesn't work with the parse.y of 2.7, so bisecting is more challenging than usual.

After the problem has been determined, then an appropriate fix needs to be determined. This is likely more challenging, and requires knowledge and/or study of how method caching works in Ruby.

If this isn't work you are comfortable doing yourself, and it's important enough that you are willing to pay to have it fixed, you could pay a developer to do so on your behalf, or you could offer a bounty for a developer to fix it for you.  There are no guarantees of success, of course, but it likely increases the odds.

Considering this bug has been around for about 4 years, and this is the first time it has been reported, this doesn't seem like a major issue, and it should be fairly easy to work around by overriding the method before calling `super`.  That said, I would still like to see it fixed, and likely will work on it more myself at some point.  However, I don't have extensive knowledge of Ruby's method caching, and there are other bugs I'm working on fixing.

----------------------------------------
Bug #20716: Different instance_method behavior in Ruby 2.7 and Ruby 3.x
https://bugs.ruby-lang.org/issues/20716#change-109690

* Author: natton (Tien Truong)
* Status: Open
* ruby -v: 3.3.1
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
Hi, I am working on upgrading our project from 2.7 to 3.x and found a breaking change in `instance_method` behavior.
Here is the code snippet
```
module A
  def test(*args)
    super
  end
end

module B
  def test(a)
    puts a
  end
end

B.prepend(A)

a = lambda do
  puts 'lambda'
end

class C
  include B
end

B.instance_method(:test).bind(C.new).call(1)
# Ruby 2.7: 1
# Ruby 3.0: 1
# Ruby 3.1: 1

B.module_exec do
  define_method(:test, a)
end

B.instance_method(:test).bind(C.new).call
# Ruby 2.7: lambda
# Ruby 3.0: wrong number of arguments (given 0, expected 1) (ArgumentError)
# Ruby 3.1: wrong number of arguments (given 0, expected 1) (ArgumentError)
```
I don't know if this is a bug or a correct intention.

My specs:
- Ruby manager: rbenv
- Tested on 
    - ruby 2.7.4p191 (2021-07-07 revision a21a3b7d23) [x86_64-linux]
    - ruby 3.0.7p220 (2024-04-23 revision 724a071175) [x86_64-linux]
    - ruby 3.1.4p223 (2023-03-30 revision 957bb7cb81) [x86_64-linux]
    - ruby 3.2.3 (2024-01-18 revision 52bb2ac0a6) [x86_64-linux]
    - ruby 3.3.1 (2024-04-23 revision c56cd86388) [x86_64-linux]

-- 
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