[foreign-abi] RFR: 8248560: Specify the behaviour of the ForeignLinker returned by CSupport::getSystemLinker [v4]

[Athijegannathan Sundararajan]

On Wed, 16 Sep 2020 11:27:05 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Hi,
>> 
>> This patch creates a new class called CLinker, which extends ForeignLinker. The new class documents how linking works
>> in the class's javadoc. This is done in a separate class since the specification is only relevant to linkers that
>> support the C ABI.  With the new class there was no more need to have CSupport, so the contents of CSupport has all
>> been move to CLinker.
>> After some offline discussion with Maurizio, we realized that it doesn't make much sense to expose platform specific
>> layout constants, since it is not possible to combine them with a platform specific linker any way, so for a particular
>> platform, there is only one set of layouts that can be used, namely the ones that are dynamically picked based on the
>> current platform. For that reason, all platform specific layouts have instead been moved to an internal PlatformLayouts
>> class. In order for downstream APIs (like jextract) to be able to filter out the ABI attributes from layouts, I've
>> added a String constant to CLinker that is used as a name prefix for all the ABI attribute names, so clients can for
>> instance filter attribute names using `.startsWith(ABI_ATTR_NAME)`.  The ForeignLinker::name method has been dropped in
>> favor of an internal enum.  The rest of the patch is just mechanical CSupport -> CLinker renames.  Thanks, Jorn
>
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove public attribute name prefix

Tests add @module clauses. Perhaps not needed - earlier code too used those classes and imports. We had global config
for those modules? Perhaps that could be removed now that we've specific tests having @module. Not super critical
though.

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Marked as reviewed by sundar (Committer).

PR: https://git.openjdk.java.net/panama-foreign/pull/327