A
The solution was to run
I post only so any other poor soul can be saved the time I wasted discovering this.
portupgrade
from Firefox 20 to Firefox 21.01 and 21.02-1 resulted in Firefox crashing with a bus error and dumping core. After eliminating all the obvious things and rebuilding all the already up to date dependencies, it still crashed with the same error on startup.The solution was to run
make config
and uncheck the option to build with OPTIMIZED_CFLAGS, an option which I've had checked since time immemorial.I post only so any other poor soul can be saved the time I wasted discovering this.