RFR: 8313374: --enable-ccache's CCACHE_BASEDIR breaks builds [v4]

[Erik Joelsson]

On Mon, 31 Jul 2023 07:00:00 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

>> https://bugs.openjdk.org/browse/JDK-8313374
>> --enable-ccache's CCACHE_BASEDIR breaks builds
>
> Jan Kratochvil has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Adjust compatibility with FILE_MACRO_CFLAGS.

I understand why you need `fix-deps-file` when using `ccache`, but do you also need `MakeCommandRelative`?

I'm not surprised that ccache support has bit rotted over the years as we aren't seeing much benefit from it in practice, so it's probably not used much. In the ideal case, it certainly speeds up the build a lot, but that case is very rare, at least in our build scenarios. I wouldn't mind removing it at this point, but if we can fix it with a simple patch like this, then that works too. Note that trying to setup ccache correctly without support in the build is quite tricky to get right. That's why I thought it necessary to handle it explicitly in the makefiles.

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PR Comment: https://git.openjdk.org/jdk/pull/15080#issuecomment-1669613841