[BUG]: ECJ appears to flush custom JavaFileManager objects repeatedly

[ascopes]

Follow up of #958 (comment), as requested by @stephan-herrmann.

It appears that when using a custom JavaFileManager implementation, the call to .flush at the end of the compilation run is repeated numerous times. It seems to vary depending on what the project is doing but for less than a dozen source files, I have observed it being called more than 20 times in a row.

[jukzi]

Please add info how to reproduce, what is the bad consequence and what you expect.

[ascopes]

If you view the linked comment and thread, I have a library at github.com/ascopes/java-compiler-testing that has a feature/v5-ecj branch where I am integrating with ECJ.

If you enable compiler.fileManagerLoggingMode(LoggingMode.ENABLED) on any of the compiler integration tests such as https://github.com/ascopes/java-compiler-testing/blob/feature/v5-ecj/java-compiler-testing/src/test/java/io/github/ascopes/jct/integration/compilation/BasicLegacyCompilationIntegrationTest.java#L46, this will result in the library logging every since API call that ECJ makes to the JavaFileManager. For some test cases, I have seen a large number of consecutive flush calls at the end of the compilation process.

[jukzi]

I have seen a large number of consecutive flush calls at the end of the compilation process.

Why is that a problem? Will you work on a fix? Without selfcontainig reproducer of a problem it is unlikely anybody else will work on it.

[ascopes]

It is not a "problem" but ECJ calling flush 25 times rather than 1 does not feel like it is valid behaviour. Happy to close if it does not constitute an issue.

[jukzi]

Closing as won't fix. Still anyone is invited to propose a PR to improve the code.

[szarnekow]

@jukzi Stephan was working tirelessly with @ascopes in the past weeks to fix a bunch of things in this area and asked for small tickets explicitely. Please don't close tickets without exploring the context.

[szarnekow]

Sadly I cannot reopen it.

[brychcy]

I'll reopen it for now as requested.