Description of the problem / feature request:
Clang 9 introduces the -ftime-trace option which dumps a .json file containing the tracing information from the compilation run. It would be great to retrieve this from sandbox for the relevant C++ compilation rules.
Feature requests: what underlying problem are you trying to solve with this feature?
Let people use Clang 9's compilation tracing with Bazel native CC rules.
Have you found anything relevant by searching the web?
No
m3rcuriel
All 4 comments
This is great, I have been trying to get this to work but unfortunately the .json file always gets deleted. I understand it is running in the sandbox but can anyone explain why the unexpected file gets deleted and the expected files are preserved?
Does anyone have a workaround? We would like to enable this for our codebase.
jpan127
on 16 Jan 2020
When I saw my JSON trace files had been deleted, I tried re-running my build command with --spawn_strategy=standalone and it kept the files around. It's not building in the sandbox, but for me it was useful enough as a one-off build to be able to debug what was taking long to compile.
e.g.
bazel build //foo --copt=-ftime-trace --spawn_strategy=standalone
jez
on 2 May 2020
Thanks so much for the helpful tip @jez !
ArekSredzki
on 2 May 2020
Someone at our company was able to add support for this using an aspect. I've asked them to chime in here if they have time.
ArekSredzki
on 9 Oct 2020
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Most helpful comment
When I saw my JSON trace files had been deleted, I tried re-running my build command with
--spawn_strategy=standaloneand it kept the files around. It's not building in the sandbox, but for me it was useful enough as a one-off build to be able to debug what was taking long to compile.e.g.