RFR: 8276789: Support C++ lambda in ResourceHashtable::iterate [v4]

[Kim Barrett]

On Thu, 2 Jun 2022 05:08:18 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Interesting. I got problems when I converted BitMap to support both closures and lambdas. The problem might have been that the iterate function took an specific closure class, and didn't use a template.
>
> [Not a review, just a drive-by comment]
> SFINAE operates on arguments and signatures; it doesn't reach into the bodies
> of (potential) callees like that. The disambiguation is happening because one
> argument (the Closure object) is passed as a pointer, while the other is a
> lambda object (not a pointer). In the pointer to closure object case the ITER*
> overload is a better match, so is selected. In the lambda case, it's not a
> pointer so only the non-pointer overload is applicable.

(And SFINAE _can't_ reach into the body like that, since the body might not be available.)

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PR: https://git.openjdk.java.net/jdk/pull/8761