[lworld] RFR: 8372515: [lworld] Plumb in javac flags for compiling with preview mode [v4]

[David Beaumont]

On Wed, 10 Dec 2025 10:41:34 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Also, nulling out "sharedResources" during close() for better GC cleanup is doable, but not completely trivial, since it adds "post-closure" failure modes that didn't exist before.
>> I do think that *somewhere* we should be detaching the index for garbage collection, but maybe all its users are sufficiently well scoped that it's unlikely to matter.
>
> In general, I prefer to err on the side of correctness (as you did here). Given all allocation of JRTIndex go through the factory (and the shared file system resources), if we detect something suspicious it likely means there's an issue somewhere. Now, we could argue if this should be a crash or not -- but if it's not then we'll likely never know about it.
> 
> Note -- javac has a class to do some assertion checks -- see com.sun.tools.javac.util.Assert.
> 
> So this could also be rewritten as:
> 
> 
> Assert.check(sharedResources.release(this), "Already closed");

I don't see this as an assertion because I could easily write a test which causes it to happen.
To me, assertions are for code invariants that "should never happen" due to the immediate surrounding code and logic. This can be triggered by a badly behaved caller, which (due to the public nature of this class) could be anyone.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1761#discussion_r2622742076