RFR: JDK-8255544: Create a checked cast [v2]

[Coleen Phillimore]

On Sat, 31 Oct 2020 14:02:07 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> In many places we've added C-style casts to silence compiler warnings, for example when truncating a size_t to an int when we know the size_t is a small struct. Such casts are inherently risky, because they effectively disable useful compiler warnings. We should add a form of cast that checks at runtime that a truncation does not overflow.
>
> Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:
> 
>   JDK-8255544: Create a checked cast

Looks good to me.

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Marked as reviewed by coleenp (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/904