RFR: JDK-8267936: PreserveAllAnnotations option doesn't expose the annotation to Java code

[David Holmes]

On 31/05/2021 4:11 pm, Jaroslav Tulach wrote:
> On Sun, 30 May 2021 23:03:55 GMT, David Holmes <david.holmes at oracle.com> wrote:
> 
>> But we should add in some tests.
> 
> Right, I was surprised by missing tests as well. I've just created a _"standalone"_ commit 0f689ea  that adds such test and also shows the way I am currently using the `-XX:+PreserveAllAnnotations` flag. It [requires some tricks](https://github.com/openjdk/jdk/pull/4245/files#r642231785) with `ClassLoader` and bytecode manipulation to change the retention to `RUNTIME` and then (in combination with `-XX:+PreserveAllAnnotations`) the annotation is accessible.

I was thinking (not for this PR of course) of something a bit more 
comprehensive that simply defined a class with methods/fields with both 
class-retention and runtime-retention attributes (there are 8 cases of 
"invisible" annotations IIRC) that verified their presence/absence both 
with and without PreserveAllAnnotation.

> The test in 0f689ea is _"standalone"_ - e.g. it can be merged without my other changes. However I continue to hope the change in `Class.getAnnotation` could get in: the `-XX:+PreserveAllAnnotation` option hasn't caused any issues since Java 5 - this is the first improvement ever requested. Possibly also the last one - tests are written & the functionality works - what else could one want?

I'll have to defer to core-libs folk here. As I said I would have 
expected the Java code to just ask the VM for the annotations applied to 
a given element, and that the VM would return the CLASS retention ones 
if PreserveAllAnnotation was set. I don't understand how the 
AnnotationParser is used in general and as it is not part of the VM the 
  part of the JVMS that talks about exposing invisible annotations is 
not really applicable. Perhaps an oversight when this API was created, 
but I don't know.

Cheers,
David

> -------------
> 
> PR: https://git.openjdk.java.net/jdk/pull/4245
>