Generic type information for classes within closures not emitted by javac 11.0.15

[Vicente Romero]

Hi Dawid,

Thanks for the additional information, but from your findings it seems 
like the issue has been fixed in recent releases. Fixing it in previous 
releases seems to me like a sustaining / support job,

Thanks,
Vicente

On 6/10/22 08:48, Dawid Weiss wrote:
>
> Just FYI - I did a little bisecting archeology and it's this issue:
> https://bugs.openjdk.org/browse/JDK-8215470
>
> The signatures from the nested class are fine after that commit and 
> erased/ missing before. So the bug is present in anything up to jdk-13-ga.
>
> Dawid
>
> On Wed, Jun 8, 2022 at 10:08 PM Dawid Weiss <dawid.weiss at gmail.com> wrote:
>
>
>     Good evening,
>
>     I've spent an interesting day debugging a very awkward error in
>     Google Guice: a binding would work in JDK17 but would result in an
>     odd (and misleading) error information under JDK11. This turns out
>     to be a problem with generic signatures emitted by the
>     corresponding compilers.
>
>     I narrowed it down to essentially something like this [full source
>     at 1]:
>
>     Callable<Void> r =
>             () -> {
>               class Foo1 {
>                 public Map<String, Integer> field;
>               }
>
>               System.out.println("Foo1.field type: " +
>     Foo1.class.getField("field").getGenericType());
>               return null;
>             };
>         r.call();
>
>     When I compile and run this snippet under java 11.0.15, I get only
>     the following signatures for generic types:
>
>     Foo1.field type: interface java.util.Map
>
>     if you move the inner class declaration outside of the closure,
>     proper generic info is stored and then loaded/ printed:
>
>     Foo2.field type: java.util.Map<java.lang.String, java.lang.Integer>
>
>     In Java 17.0.3, this compiles and works fine and I can't find any
>     issue where this was fixed. Is this a class bytecode constraint
>     somewhere? My reading of the JLS [2] would suggest the signature
>     is mandatory, even if emitted from within that nested class Foo1?
>
>     Any pointers would be appreciated!
>     Dawid
>
>     [1] https://gist.github.com/dweiss/d77452c52daa178e041adce145c2e86a
>     [2]
>     https://docs.oracle.com/javase/specs/jvms/se11/html/jvms-4.html#jvms-4.7.9.1
>
>
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