RFR: 8351842: Test issues on Windows with combination of --enable-linkable-runtime and --with-external-symbols-in-bundles=public [v2]

[Erik Joelsson]

On Thu, 13 Mar 2025 07:39:20 GMT, Christoph Langer <clanger at openjdk.org> wrote:

>> This PR addresses an issue that can be observed when building on Windows with configure options `--enable-linkable-runtime` and `--with-external-symbols-in-bundles=public`.
>> 
>> The problem is that with this special build configuration, we build two sets of .pdb files for the binaries. The first set is the standard debug symbols files named <binary-name>.pdb. The second set consists of stripped debug symbols file called <binary-name>.stripped.pdb which have less information but enough to present line numbers in hs-err files.
>> 
>> During build we use the *.stripped.pdb files for compiling the jmods and also the bundle files. However, in the images folder, both sets of .pdb files exist. The tests for runtime linking will now, in the absence of jmod files, pick up the .pdb files (without *stripped*) from images, but in the runtime the hashes of the *stripped* files are stored.
>> 
>> With this change, the standard .pdb files in the `--with-external-symbols-in-bundles=public` configuration are now the stripped files and we create a set of full pdb files named *.full.pdb. Jmods and Bundles still contain the stripped pdb files and we also fix the issue that the debug symbols bundle also contained stripped pdb files so far. With this fix, it will contain the full pdb files and extracting these over a JDK runtime will replace stripped pdbs with full pdbs.
>
> Christoph Langer has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix tests

> I'll add here that the implementation of JEP 493, does nothing special. It takes what's in the JMODs _at build time_ when `jlink` is being run and uses that as the "source of truth" when it comes to hash sums. It sounds to me that when `jlink` runs during the build it only sees `*.stripped.pdb` files (renamed as `*.pdb`). If something is being done **after** the `jdk` image has been created (by `jlink`) and changes files (like copying full `*.pdb` files over the stripped ones that are actually in the JMODs) then this is the root cause of this bug. Rightfully so, since the `*.pdb` files in the JDK image no longer match the ones in the JMOD files. Is that the case?

Yes, that is the root cause of this issue that I tried to allude to in my last comment. The "jdk image" that we produce in the build and run tests from isn't exactly what jlink produced, or what ends up inside the zip/tar.gz bundles. Historically we always put the debug symbols in that image, for developer convenience. When introducing the stripped/public pdb support, we managed to preserve this property of the jdk image. This is basically why in this case, the image isn't representative of the shipped product and the tests fail.

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PR Comment: https://git.openjdk.org/jdk/pull/24012#issuecomment-2721258333