Build System Project - Latest Update

[David Burns]

Below is a highlight of all work the build peers have done since the last
report[1].

The build peers have been working to get faster builds in automation as
well as well as local developers. We have updated the way that Taskcluster
decision and linting jobs use version control[2]. This has driven down the
times for those jobs from 3 minutes to ~9 seconds.

We are still working on getting the sccache rewrite out. We are hitting a
few issues on try but this is to be expected. Hopefully this will be out
soon.

We’re also looking into running automation builds in EC2 on instances with
more and faster CPU cores so they complete faster[3].

On the local build side we have moved some of the header checks[4] to the
python configure. These were fairly self contained configure steps and ripe
for porting. They removed ~1300 lines of configure code which is a huge
win! We have also been working through some of the potential problems with
moving to a new build backend. This is going to be a little slow at first
as we try get specific parts using the alternate build backend.

Some initial work on replacing the NSS build system is showing great
promise[5].

We have also been moving Windows specific configure code around. This is
part of our goal to make that step faster in the build. Nathan, our intern,
has also been making great strides in his work to move MozillaBuild to
msys2 allowing easier hackability of the build. He also did his intern
presentation[6]. I highly recommend you watch it!

Nathan will be leaving us at the end of next week (12 August) and the build
peers want to thank him for all his hard work over his internship and wish
him luck in his future endeavours! .

[1]
https://groups.google.com/d/msg/mozilla.dev.platform/4Vyez4stDyg/jlQeQ5TACAAJ

[2] https://bugzilla.mozilla.org/show_bug.cgi?id=1247168

[3] https://bugzilla.mozilla.org/show_bug.cgi?id=
<https://bugzilla.mozilla.org/show_bug.cgi?id=1269517>1290282

[4] https://bugzilla.mozilla.org/show_bug.cgi?id=1269517

[5] https://bugzilla.mozilla.org/show_bug.cgi?id=1237872#c3

[6] https://air.mozilla.org/down-the-rabbit-hole/