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

[Paul Sandoz]

On Tue, 15 Sep 2020 14:36:08 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

src/jdk.incubator.foreign/share/classes/jdk/incubator/foreign/CLinker.java line 42:

> 40:
> 41: /**
> 42:  * This interface is a used as a super class for all ForeinLinker implementations that

Suggest as the first paragraph: "A foreign linker specializing for C Application Binary Interface (ABI) calling
conventions. Instances ... platform C ABI."

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