Self-granted permissions do not improve correctness

[Alan Bateman]

On 08/01/2025 22:09, David Lloyd wrote:
> The Java module system features several ways to restrict or grant 
> access to various capabilities. Two of these access permissions can be 
> shown to be of questionable benefit but clear detriment in practice. 
> They are `reads` and `uses`.
>
> Both of these permissions, if not granted, cause a run time exception 
> at various points. Both can be trivially self-granted without any 
> restriction to speak of. I have been hard-pressed to identify any 
> incorrect operation, error condition, or security condition which is 
> averted due to the presence of these permissions. However it is not 
> hard to identify problems that they introduce, especially in 
> reflection-heavy frameworks.

Core reflection assumes readability [1] so reflection based frameworks 
don't need to add read edge at runtime. One of the motivations for 
adding read edges at runtime (with Module::addReads) is code generated 
at runtime with references to classes/methods/fields in modules that the 
current module didn't read at compile-time.

Is your mail about reflection with method handles? Asking because the 
access checks done when creating a method handle is the same as bytecode.

I assume your issue with `uses` is the check in ServiceLoader. I found 
Mark's reply to you on this from 2016 [2].

-Alan

[1] 
https://openjdk.org/projects/jigsaw/spec/issues/#ReflectionWithoutReadability
[2] 
https://mail.openjdk.org/pipermail/jpms-spec-experts/2016-December/000524.html
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