On 21/04/2020 14:01, Doug Simon wrote:
Hi Gary,
I cannot understand why --add-reads does not work and have reached out
to Alan Bateman for more insight.
I read through the thread [1] and I don't see an obvious solution to this.
The main issue here is that org.grfstuff.compiler wants to provide an
implementation of org.graalvm.compiler.hotspot.HotSpotBackendFactory but
that service type is not in org.grfstuff.compiler and
org.graalvm.compiler.hotspot is not exported to org.grfstuff.compiler by
any of the modules that it reads. The post resolution consistency check
that it trips up on is specified in the Configuration API docs if you
are interested.
I assume `--add-exports
jdk.internal.vm.compiler/org.graalvm.compiler.hotspot=org.grfstuff.compiler`
was added in an attempt to workaround this but that CLI option is the
equivalent of jdk.internal.vm.compiler invoking Module::addExports after
the module graph has been reified. It doesn't impact resolution or any
of the post resolution consistency checks at run-time. Yes, there is an
unfortunate difference between between compile-time and run-time in this
regard but that is something for another discussion.
I don't think there are any obvious workarounds. The Module API defines
addXXX methods to export or open packages at run-time, extend
readability or add a service dependences but it doesn't define
addProvides. I think it came up once during JDK 9 but more in the
context of symmetry rather than a compelling use-case. It's not clear
that the issue under discussion here is compelling enough, needs more
thought as the scenario is a bit weird. If org.grfstuff.compiler was co
developed with jdk.internal.vm.compiler then it could use a qualified
export of course.
Initially I thought you could workaround this by moving
org.grfstuff.compiler to the class path but this it's not going to work
as ServiceLodaer usage in Graal seems to use module layers as congtext,
so it will not find implementations on the class path.
-Alan
[1] https://mail.openjdk.java.net/pipermail/graal-dev/2020-April/005949.html
