Integer overflow/underflow

Official Description

6.7.2.2 It is an error if an integer operation or function is not performed according to the mathematical rules for integer arithmetic.

This appears to mean that it is an error if integer operations or functions overflow or underflow. So for example

   maxint+maxint

should be an error since

   maxint = 2,147,486,647

but due to integer overflow

   maxint+maxint = -2

This error is never reported.