RFR: 8255449: Improve the exception message of MethodHandles::permuteArguments

[Jorn Vernee]

On Wed, 28 Oct 2020 09:20:54 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> 
> 
> This looks okay to me. Someone from core-libs should take a look as well.
> 
> As the follow-up, maybe reconcile that method returns normally only with `true`, and throws exceptions otherwise. There are some uses like `assert(permuteArgumentChecks(...))` that apparently depend on this, how necessary are those?

It checks that the normalized reorder array is correct as well.

I'm a little reluctant to remove it right now though, since I just discovered a bug in that area: https://bugs.openjdk.java.net/browse/JDK-8255531 and it would be nice to have some extra safety nets when fixing that I think.

I agree it looks a little ugly, but let's leave it for now.

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PR: https://git.openjdk.java.net/jdk/pull/878