[ruby-core:97662] [Ruby master Bug#16748] Different behaviour between a hash and multi-Array when passing 2 arguments to a proc

Issue #16748 has been updated by mame (Yusuke Endoh).

Status changed from Open to Rejected

The behavior of 2.5.5 was wrong.  `Array#map` yields each element, in this case, `['one', 'two']`, an array of two elements.  The lambda requires two arguments, but one array is passed, which should raise "wrong number of arguments".

You may want to use `-> (ary) { ary[0] }` instead of `-> (one, two) { one }`.  Or you can use `proc {|one, two| one }`.

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Bug #16748: Different behaviour between a hash and multi-Array when passing 2 arguments to a proc
https://bugs.ruby-lang.org/issues/16748#change-84869

* Author: Mattruby (Matthew Nash)
* Status: Rejected
* Priority: Normal
* ruby -v: 2.7.0
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
In Ruby 2.5.5 i get what i'm expecting
```ruby
test = -> (one, two) { one }
[['one', 'two']].map(&test)
=> ["one"]
```

In Ruby 2.7.0 this doesn't work
```ruby
test = -> (one, two) { one }
[['one', 'two']].map(&test)
wrong number of arguments (given 1, expected 2) (ArgumentError)
```

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Screen Shot 2020-04-01 at 16.47.37.png (205 KB)


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