Implement features required by Xcode

[scoopr]

These commits allow me to use sccache with Xcode.

Firstly, I just mark -index-store-path as Hard, as it is easy to configure Xcode not to use that. Not sure how impossible that would be to implement otherwise, didn't look in to it.

And secondly, I'm artifacting the dep (.d) files and the -serialize-diagnostics (.dia) files, as Xcode seems to always request them, and the build will fail without them.

When using it, I need to run the sccache server outside of Xcode, as otherwise it seems that Xcode will keep waiting for the daemon to timeout.

Then I have configured in Xcode build settings the CC/CXX variables, currently to a launcher script that sets the env variables and calls sccache with the right arguments (I am using it through cmake though). The setup might be improved now that I got it to work.

[sylvestre]

thanks
it would be nice to add some docs + add a test if possible
thanks

[scoopr]

Updated the tests and added some docs.

If there are additional concerns, it might be few weeks until I can get back to this.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 51.61290% with 15 lines in your changes missing coverage. Please review.

Project coverage is 40.68%. Comparing base (0cc0c62) to head (0c8a7e2).
Report is 78 commits behind head on main.

Files with missing lines	Patch %	Lines
src/compiler/gcc.rs	53.33%	8 Missing and 6 partials ⚠️
src/compiler/msvc.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2257      +/-   ##
==========================================
+ Coverage   30.91%   40.68%   +9.77%     
==========================================
  Files          53       54       +1     
  Lines       20112    20732     +620     
  Branches     9755     9636     -119     
==========================================
+ Hits         6217     8435    +2218     
- Misses       7922     8150     +228     
+ Partials     5973     4147    -1826     

☔ View full report in Codecov by Sentry.
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[sylvestre]

About test, I was thinking about something like in https://github.com/mozilla/sccache/blob/main/.github/workflows/integration-tests.yml

[scoopr]

Sorry about the churn for getting that integration test running, I don't think I have a good way to test it locally, so I'm developing it a bit blind.

[sylvestre]

no worries. Could you please write a tiny PR that I could merge quickly so that you get the CI without approval?

[sylvestre]

for example, typo fix like:
src/lru_disk_cache/mod.rs:142: maintence ==> maintenance

[sylvestre]

well, looks like it worked :)

[scoopr]

Yep, the output now looks like what I expected. I don't think I have anything to add it, so on my side its ready, if no other concerns arise.

[sylvestre]

could you please add a comment explaining why a wrapper script is needed

[scoopr]

Its actually explained in the docs (dfe8c5b#diff-8f7ae669918b1de5a217f0f28f8becd7d0f92625c4b8334b733315b8199dd102R47), but I guess I could add a comment here.

The issue is that I can't just set CC="sccache clang++", because it interprets the whole CC variable as a command, so its searching for a file called sccache clang++ (so space is part of the command name). If you have other ideas for a workaround, I'm all ears.

[sylvestre]

yeah but i would prefer to have it next to the code :)

[scoopr]

It seems the continuous job failed, is it due to something I did, or is it something else?

[sylvestre]

nope, we have some intermittent sometimes (when the cache is full i guess)