RFR: 8313374: --enable-ccache's CCACHE_BASEDIR breaks builds

[Julian Waters]

On Sat, 29 Jul 2023 13:58:37 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

> https://bugs.openjdk.org/browse/JDK-8313374
> --enable-ccache's CCACHE_BASEDIR breaks builds

@jankratochvil The change here will force ccache to write absolute paths for all compilations, which may cause cached object file comparisons to fail sometimes, and I'm not sure we'd want that? Have you tried running make clean before recompilations? (Note that there are 2 different targets for this, make clean for cleaning build artifacts and make dist-clean which removes almost everything in the build directory).

Weird bugs can happen sometimes if clean is not run, as stated in the warning message each time configure is run. I also read the issue in the tracker, and I don't think removing --enable-ccache entirely is correct, as we need that option to check for certain things (like if ccache can handle precompiled headers) and also disable aliasing ccache as the compiler during the build for that exact reason. I'm also not too sure how removing CCACHE_BASEDIR helps fix the issue, since all it does it change the command passed to the real compiler, could you elaborate on that slightly more?

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PR Comment: https://git.openjdk.org/jdk/pull/15080#issuecomment-1657529196