From: "jeremyevans0 (Jeremy Evans) via ruby-core" <ruby-core@...>
Date: 2024-09-07T00:00:44+00:00
Subject: [ruby-core:119094] [Ruby master Bug#20716] Different instance_method behavior in Ruby 2.7 and Ruby 3.x

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


This behavior isn't related to `instance_method`.  It occurs in the following code:

```ruby
module A
  def test(*args)
    super
  end
end

module B
  def test(a)
    puts a
  end
end

class C; end

B.prepend(A)
C.include(B)

C.new.test 1

module B
  def test
    puts 'lambda'
  end
end

C.new.test
```

It also happens when you replace `C.include(B)` with `C.prepend(B)`.

It does not happen when you replace `B.prepend(A); C.include(B)` with `A.include(B); C.include(A)`.  It also does not happen if a class directly prepends a module, such as in this example:

```ruby
module A
  def test(*args)
    super
  end
end

class B
  def test(a)
    puts a
  end
end

B.prepend(A)

B.new.test 1

class B
  def test
    puts 'lambda'
  end
end

B.new.test
```

It seems like the conditions are:

* Class includes or prepends module X that prepends module Y
* Both X and Y define method M
* Y's definition of M calls `super`
* X's definition of M is overridden after `super` method call is cached

----------------------------------------
Bug #20716: Different instance_method behavior in Ruby 2.7 and Ruby 3.x
https://bugs.ruby-lang.org/issues/20716#change-109681

* 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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