It would be really useful if the messages generated by MOZ_CRASH_UNSAFE_PRINTF were included in the failure summary. Right now I see a generic PROCESS-CRASH line like: PROCESS-CRASH | /FileAPI/blob/Blob-constructor.html | application crashed [@ MOZ_CrashPrintf] But I then have to hunt back through the log to find the actual error information. This is reported inside "Hit MOZ_CRASH(blah)" it seems.

Hi! Do you have a link to an example log?

Sure do: https://treeherder.mozilla.org/#/jobs?repo=try&revision=c8cef1698139de41582cec05030facd4b1e5cc60&group_state=expanded&selectedJob=184158249 https://treeherder.mozilla.org/logviewer.html#?job_id=184158249&repo=try&lineNumber=1838 The crash reason is split over two lines because I put a newline in my printf string - normally that wouldn't be the case.

Thank you for the links :-) The line is question is: [task 2018-06-21T13:14:53.668Z] 13:14:53 INFO - PID 1284 | Hit MOZ_CRASH(Multiple zones found for MessageEvent We're trying to move Treeherder away from hardcoding every every permutation of error related string, in favour of having the build system/test suite/things that wrap it (eg mozharness) set relevant log error levels (which Treeherder's log parser already honours). ie for the line above, "INFO - " should be "ERROR - ". I believe this would be achieved by modifying: https://dxr.mozilla.org/mozilla-central/source/testing/mozharness/mozharness/base/errors.py

Isn't that just another case of bug 1399993?

Ah yes