[ruby-core:117994] [Ruby master Bug#20505] Reassigning the block argument in method body keeps old block when calling super with implicit arguments

24 May 2024

      Issue #20505 has been updated by Earlopain (A S).

nobu (Nobuyoshi Nakada) wrote in #note-1:
...
I think that's what it is.
`Proc` is an instantiated block representation, but not a block itself.
Ok, I see what you mean. This makes sense, somewhat. You could also just assign a string literal which makes even less sense, didn't think about that beforehand

You do have two values hiding behind the same name which is pretty confusing. I would expect super to take the modified argument and raise when it is not blocklike, or perhaps raise earlier on assign when not blocklike.

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Bug #20505: Reassigning the block argument in method body keeps old block when calling super with implicit arguments
https://bugs.ruby-lang.org/issues/20505#change-108416

* Author: Earlopain (A S)
* Status: Open
* ruby -v: 3.3.1
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
You can call super without arguments and parenthesis to pass along all the enclosing method arguments to the parent method.

You can modify positional and keyword arguments before the call to super, and the parent method will recieve these modified values. With the block arg however that isn't the case:

```rb
class A
  def positional_arg(a)
    puts a
  end

  def block_arg(&block)
    yield
  end
end

class B < A
  def positional_arg(a = nil)
    a = 'b'
    super
  end

  def block_arg(&block)
    block = proc { puts 'b' }
    super
  end
end

B.new.positional_arg('a')
B.new.positional_arg
B.new.block_arg { puts 'a' }
B.new.block_arg
```

I would expect this snippet to print `b` four times. The actual output is `b` `b` `a` and `LocalJumpError`. To get the desired output I must pass the block along explicitly with `super(&block)`.

I hope my example explains the issue good enough. I have looked through issues here and searched for documentation and haven't found any mention of this behaviour. Sorry if I missed something somewhere.

-- 
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