[foreign-memaccess+abi] RFR: 8308293: A linker should expose the layouts it supports

[Per Minborg]

On Thu, 15 Jun 2023 13:18:29 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> src/java.base/share/classes/jdk/internal/foreign/abi/AbstractLinker.java line 280:
>> 
>>> 278:                 .orElseGet(() -> FunctionDescriptor.ofVoid(stripNames(function.argumentLayouts())));
>>> 279:     }
>>> 280: 
>> 
>> Would it make sense to add a "hook" that exotic platforms can use to modify the initialization of the Map?
>
> If you mean a public hook, no. Because the set of canonical layout is fixed by the linker impl. If you mean an internal hook, yeah, that might make sense (but can also be added later, if needed). One such example would be adding "long double" on Windows (in which this type just decays to `double`).

Yes, I meant an internal hook only for "porters".

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PR Review Comment: https://git.openjdk.org/panama-foreign/pull/839#discussion_r1231044565