Proposal: Allow illegal reflective access by default in JDK 9

Alan Bateman Alan.Bateman at
Fri May 19 11:05:35 UTC 2017

On 19/05/2017 10:48, Volker Simonis wrote:

> :
>  From my understanding, at run-time, "open" implicates "exports" (i.e.
> if a module M1 opens a package P for some other module M2 it also,
> implicitly exports P to M2). The  "big kill switch" in both, its old
> and in the newly proposed form, usually only refers to "enabling
> reflective access" but doesn't explicitly mentions that it will also,
> implicitly export the respective packages. Also, the usage of the
> "kill switch" only produces warnings for reflective accesses which are
> enabled by the option itself (and not at the same time, explicitly
> allowed by --add-opens directives). But it doesn't warn about the
> simple, non-reflective accesses to packages which are implicitly
> exported by the kill switch as well.
You are correct. If the package is opened at run-time:

1. All public members of public types in the package are accessible. 
This includes both static and reflective access.

2. All members of all types in the package can be reflected on when 
using setAccessible or privateLookupIn.

The reason you don't get warnings with the static references is because 
access checking in the VM is very low level and we deliberately decided 
to avoid the invasive changes needs to report warnings here. The latest 
proposal does not change this, it's just too late in JDK 9 to take on 
this surgery.


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