From: "matz (Yukihiro Matsumoto)" <noreply@...>
Date: 2022-06-16T06:44:32+00:00
Subject: [ruby-core:108949] [Ruby master Feature#18461] closures are capturing unused variables

Issue #18461 has been updated by matz (Yukihiro Matsumoto).

Status changed from Open to Rejected

Rejected. Ruby and JavaScript are different languages.
Upon existence of `eval`, the impact of removing unused variables from closures are far bigger in Ruby. The optimization should not be mandatory.
If there's no side effect (e.g. `eval` is never called with the closure), the unused variables might be removed from closures. But it seems nearly impossible to ensure no side effect.

Matz.



----------------------------------------
Feature #18461: closures are capturing unused variables
https://bugs.ruby-lang.org/issues/18461#change-98044

* Author: bughit (bug hit)
* Status: Rejected
* Priority: Normal
----------------------------------------
```rb
def foo
  a = 1
  ->{}
end
p foo.binding.local_variables # [:a]

```

Shouldn't `a` be optimized away? Like v8 does (https://bugs.chromium.org/p/v8/issues/detail?id=3491)



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