In several previous blog entries I’ve mentioned that in some recent versions of C and C++, left-shifting a 1 bit into the high-order bit of a signed integer is an undefined behavior. In other words, if you have code that computes INT_MIN by evaluating 1<<31 (or 1<<(sizeof(int)*CHAR_BIT-1) if you want to be that way) or code that does a byte swap using a subexpression like c<<24, then your program most likely has no meaning according to the standards. And in fact, Clang's integer sanitizer confirms that most non-trivial codes, including several crypto libraries, are undefined according to this rule.
An obvious fix is to tighten up the standard a bit and specify that shifting a 1 into the sign bit has the expected effect, which is what all compilers that I am aware of already do. This is what the C++ standards committee is doing, though as far as I can tell the fix doesn't officially take effect until a TC, a "technical corrigendum," is issued -- and even that doesn't finalize the thing, but it seems near enough in practice.
Anyhow, today Nevin Liber pointed out that there's a bit of news here, which is that last month the C standards committee decided that this same issue is not a defect in C and that they'll reconsider it later on, which I guess is fine since compiler implementers are ignoring this particular undefined behavior, but it seems like a bit of a missed opportunity to (1) make the language slightly saner and (2) bring it into line with the existing practice. Also you might consider perusing the full set of defect reports if you want to be thankful that you did something other than attend a standards meeting last month.