We will soon be using GCC 7 with an opt build.

We can either try to fix the issues with the GCC 7 opt build, or we can try to switch to Clang and directly fix the issues with the Clang build. Since we plan to switch to Clang anyway, it might be a better use of our time.

https://treeherder.mozilla.org/#/jobs?repo=try&tier=1%2C2%2C3&revision=9a1d5f45bf749bdc59ce03bceeed0a166aacd429&selectedJob=275809142.

Most of the failures seem to be related to IndexedDB.

Depends on D59316

https://hg.mozilla.org/mozilla-central/rev/075a66d659d2

Test which failed the last 3 runs on Linux x64 ccov and have no bug and patch yet:

• browser/components/aboutconfig/test/browser/browser_edit.js and browser/components/aboutconfig/test/browser/browser_observe.js (bc6)
• devtools/client/webconsole/test/browser/browser_toolbox_console_new_process.js (dt5)
• devtools/server/tests/browser/browser_perf-01.js and devtools/server/tests/browser/browser_perf-02.js (dt9)
• browser/base/content/test/static/browser_all_files_referenced.js (dt10)
• devtools/client/debugger/test/mochitest/browser_dbg-windowless-service-workers.js (dt16)

There are also several tests which fail frequently but not permanently (e.g. dt12) which will also need disabling. Please do a daily review of the failures and disable the ones which fail more than once per day (means at least 2 out of ~4 runs, or >=50% failure rate).

https://hg.mozilla.org/mozilla-central/rev/fb7e027b119d

The leave-open keyword is there and there is no activity for 6 months.
:marco, maybe it's time to close this bug?

We can call this fixed as most tests are now green. The remaining failing tests are tracked in separate bugs (blocking this one).