Bad exhaustive test using Record Pattern as delivered in OpenJDK 19 preview

[Michel Turpin]

Hello,

First, please excuse me for the way I send this bug report. I cannot find a
way to report it in other ways.

Looking at the description of JEP 405, it made me think of Rust enums and
pattern matching.
I tried then to play on how to write a copy of the Rust "Option" enum :
https://gist.github.com/grimly/55d414f0cc3395e87a7c813176c50ac9

But then I encountered this issue when narrowing the types I use and in
this particular instance (
https://gist.github.com/grimly/55d414f0cc3395e87a7c813176c50ac9#file-testfailing-java-L9-L12
), the compiler throws an error and reports the switch is not exhaustive.

Given in my code "Option" is sealed and may only be "Some" or "None", I
would expect listing both options to make my cases exhaustive.
Adding a default case, I also fail to produce an instance that would
trigger it.

Best regards,
Michel

-- 

Michel TURPIN
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