Comment 338 for bug 727064

"Congratulations, you have knowingly made the system more unreliable in order to gain nothing."

Actually, it's not nothing.

Several bugs were discovered as a result of this change and are now being fixed. This seems to be a somewhat common bug and if it has no consequences, it will continue to become more and more widespread until the day it does have consequences. The sooner that day is, the less it will break.

In addition, in the future if modifications to memcpy do make significant optimizations possible, they won't break things. One of the obstacles to innovation is dealing with code that abuses undocumented behavior and that can lead to a culture of having to maintain bug-for-bug compatibility.

We are talking about a function that exists for exactly one purpose and it being made unsuitable for that purpose.