From: keystonelemur@...
Date: 2021-01-30T06:10:37+00:00
Subject: [ruby-core:102315] [Ruby master Bug#17595] [Pattern Matching] deconstruct_keys with zero patterns supplies nil for keys argument

Issue #17595 has been reported by baweaver (Brandon Weaver).

----------------------------------------
Bug #17595: [Pattern Matching] deconstruct_keys with zero patterns supplies nil for keys argument
https://bugs.ruby-lang.org/issues/17595

* Author: baweaver (Brandon Weaver)
* Status: Open
* Priority: Normal
* ruby -v: 3.0.0
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
Example:

```ruby
Test = Struct.new(:a, :b) do
  def deconstruct_keys(ks)
    p ks: ks
    to_h.slice(*ks)
  end
end
# => Test

Test.new(1,2) in {}
# {:ks=>nil}
# => true
```

As users may call `Array` methods against the `keys` argument I consider this a potential bug that it returns `nil` for no supplied arguments.

**Proposed Patch**: Pass an empty array instead to maintain interface consistency.



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