I was taught at a very early stage in my career by a South African photographer that you should always shoot with the brides back to the sun.
( we used fill flash anyway) That way all the amateurs among the guests got horrible results, and you sold more pictures.
For this and many other reasons like avoiding squinting and nice rim lights it is a good idea anyway. The problem came when people started using focal plane shutters and the impossibly limited sync speeds. (I kept on using leaf shutters).
To day many of the better high power flashes allow high speed flash so it is far less of a problem.
Have a look at the site I gave earlier
http://meninenuotrauka.lt/en/wedding/ for how to handle bright bride shots.