When we switched to building stylo with m-c cargo, we stopped passing --with-servo (since that expects a path to an external libgeckoservo.a to link). However, that also means that we lose the automatic definition of MOZ_STYLO everywhere. I originally just hammered this into my .mozconfig with: > export CFLAGS="-DMOZ_STYLO" > export CXXFLAGS="-DMOZ_STYLO" But I realized today that this misses the JS preprocessor, which means that our stylo pref in [1] doesn't get activated. Nathan suggested separating the two into separate configure options. I've done this, and he r+ed the patch on IRC. [1] http://searchfox.org/mozilla-central/rev/064025c802c22cd5ad122746733cbd34ea47393c/modules/libpref/init/all.js#5535

Pushed by bholley@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/96e4aed6d414 Add a separate --enable-stylo option to control MOZ_STYLO separate from the linkage effects of --with-servo. r=froydnj

I had to back this out for build bustage like https://treeherder.mozilla.org/logviewer.html#?job_id=34990873&repo=mozilla-inbound#L18506 https://hg.mozilla.org/integration/mozilla-inbound/rev/ca5efad1f688

Landed a clobber touch because even the backout was busted: https://hg.mozilla.org/integration/mozilla-inbound/rev/4d5428813b26

(In reply to Wes Kocher (:KWierso) from comment #4) > Landed a clobber touch because even the backout was busted: > https://hg.mozilla.org/integration/mozilla-inbound/rev/4d5428813b26 Sorry about that, footgun when modifying build config. MOZ_STYLO was always getting set to true. 1-line fix which I've verified locally. Filed bug 1299332 about the clobber.

belt-and-suspenders: https://treeherder.mozilla.org/#/jobs?repo=try&revision=e921c12f3d60

Pushed by bholley@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/4b36234946e3 Add a separate --enable-stylo option to control MOZ_STYLO separate from the linkage effects of --with-servo. r=froydnj