We're resolving bug 1368163 by using packaged llvm+clang 4.0.x for local macOS builds. Bug 1310852 added a check for Homebrew's custom location, but it's after the one in the state directory in the search order. This means that anyone who has installed a clang build with `mach artifact toolchain` or through a recent run of `mach boostrap` will get the wrong libclang and hit the C++ parser hang/crash issue. I think we just need to flip the order of the checks.

Comment on attachment 8884485 [details] Bug 1379341 - Prefer llvm-config from homebrew to mozbuild. https://reviewboard.mozilla.org/r/155384/#review160480 ::: toolkit/moz.configure:626 (Diff revision 1) > @imports('os') > @imports('subprocess') > def llvm_config_paths(host): > llvm_config_progs = [ > 'llvm-config-4.0', > - 'llvm-config-mp-4.0', # MacPorts's chosen naming scheme > + 'llvm-config-mp-4.0', # MacPorts' chosen naming scheme. Nit: there is no universally agreed upon policy for apostrophe-s after singular nouns, irregardless if the noun is singular or proper. For plural nouns, AFAIK it is universally accepted to omit the apostrophe-s. I would argue "MacPorts" is a singular noun since we don't have multiple "MacPort" (keeping in mind that "Ports" derives from the BSD "Ports" system). So the use of an apostrophe-s here is subjective and the old form was acceptable. That being said, I live in the USA and recognize that I speak "low English." Since you reside in a Commonwealth nation, I must automatically defer to you on matters concerning proper use of the English language. So I won't prevent you from changing this comment :)

Ha! You may have a point. I think I just learned a less-sophisticated rule in school. "Low English" often wins on complexity!

Pushed by rgiles@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/d6c1661d4040 Prefer llvm-config from homebrew to mozbuild. r=gps