[lworld] RFR: 8373825: [lworld] ForwardingFileManager always closes its delegate leading to ClosedFileSystemException in TestOriginatingElements [v2]

[David Beaumont]

On Wed, 17 Dec 2025 09:50:04 GMT, David Beaumont <duke at openjdk.org> wrote:

>> Allow users of ForwardingFileManager to specify if the delegate file manager should also be closed.
>> 
>> This fixes a use-after-close bug in TestOriginatingElements, where the system file manager and wrapping memory file manager have different, nested, lifetimes resulting in an early call to close the system file manager when the wrapper is closed, causing subsequent legitimate use of the system file manager to fail.
>> 
>> This wasn't noticed before now since the system file manager was using the singleton JRT file-system in which "close" does nothing. Now it's using a properly scoped instance of the JRT file-system which can be closed.
>> 
>> This fix could also probable go straight into mainline as a clone since it won't break anything there.
>
> David Beaumont has updated the pull request incrementally with one additional commit since the last revision:
> 
>   tidy and restore eagerly removed not-actually-dead code

test/langtools/tools/javac/classfiles/InnerClasses/T8068517.java line 110:

> 108:         try (JavaFileManager fm = ToolProvider.getSystemJavaCompiler().getStandardFileManager(null, null, null)) {
> 109:             ToolBox tb = new ToolBox();
> 110:             try (var memoryFM1 = new ToolBox.MemoryFileManager(fm, false);

I could leave this alone, but it seemed nicer to actually acknowledge that the file managers are closeable.

test/langtools/tools/lib/toolbox/ToolBox.java line 858:

> 856:          * and delegates to a default file manager for input files.
> 857:          */
> 858:         public MemoryFileManager() {

This is the vast majority of users, they don't care about the delegated instance and want it closed.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1810#discussion_r2626408506
PR Review Comment: https://git.openjdk.org/valhalla/pull/1810#discussion_r2626419184