Issue #11670 has been reported by Koichi Sasada.

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Feature #11670: Show warning to make nested def obsolete 
https://bugs.ruby-lang.org/issues/11670

* Author: Koichi Sasada
* Status: Open
* Priority: Normal
* Assignee: Nobuyoshi Nakada
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Warn without '-w' at compile time.

See https://bugs.ruby-lang.org/issues/11665




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