Fix -Wunused-const-variable warning-as-error in mozglue/misc/TimeStamp_posix.cpp. For some reason, this warning wasn't a problem until I updated to Xcode 8 and macOS Sierra 10.12 today.

I noticed this too, and came looking to see if someone had already filed this bug. I looked into it a bit further, and I think a proper fix needs more than just ifdef'ing out the declaration of kNsPerUs in TimeStamp_posix.cpp. The manpage says 10.12 introduced clock_gettime(3), which now makes us set HAVE_CLOCK_MONOTONIC when building there. Right now, TimeStamp_posix.cpp doesn't know anything about darwin, so with the proposed change, it looks like TimeStamp::ComputeProcessUptime will be a no-op on OS X (when it previously wasn't). We probably need to either make it so we don't set HAVE_CLOCK_MONOTONIC on 10.12, or fix TimeStamp_posix.cpp to be darwin-aware. Which one is right I suppose depends on if we can trust OS X 10.12's implementation of clock_gettime :) Taking a look at TimeStamp_darwin.cpp, it looks like ComputeProcessUptime is pretty similar to the BSD versions in TimeStamp_posix.cpp (which makes sense). I can try to fix this a bit later today under the assumption we can trust 10.12's clock_gettime (I don't know how to check that).

Comment on attachment 8793221 [details] [diff] [review] Wunused-const-variable_TimeStamp_posix.patch Thanks, Nicholas. I'll take down my review request.

See bug 1303212

(In reply to Mike Hommey [:glandium] from comment #3) > See bug 1303212 Looks like the fix for that (config-time check) might be the right path for this, too - there's way more in TimeStamp_posix.cpp that's darwin-unfriendly than I saw at first glance (lots of uses of /proc, which is notably absent on my mac). We're probably better off just always setting HAVE_CLOCK_MONOTONIC to false on OS X/macOS until we remove support for all versions prior to 10.12 (which I presume won't be for a while).