Issue #10028 has been reported by Nobuyoshi Nakada.

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Bug #10028: nested rest keyword argument
https://bugs.ruby-lang.org/issues/10028

* Author: Nobuyoshi Nakada
* Status: Open
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* Category: syntax
* Target version: 
* ruby -v: trunk
* Backport: 2.0.0: REQUIRED, 2.1: REQUIRED
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ネストしたrest argumentは通りますが

~~~ruby
def f((*a)) end
~~~

ネストしたrest keyword argumentはsyntax errorになります。

~~~ruby
def f((*a)) end #=> syntax error, unexpected **arg
~~~



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