On Monday 18 December 2006 17:53, Robert Dewar wrote: > Chris Lattner wrote: > > C99 says: > > > > The integer promotions are performed on each of the operands. The > > type of the result is > > that of the promoted left operand. If the value of the right operand > > is negative or is > > greater than or equal to the width of the promoted left operand, the > > behavior is undefined. > > > > Thus, it is undefined. > > So the suggested transformation is indeed valid, which is what I > thought, but some seem to be contesting this, though I don't see > on what grounds.
Note that the shift value restriction is based on the *promoted* type. Shifting an 8-bit value by >=8 is undefined. However in this case we're shifting a 32-bit value, because the left operand has been promoted. The fact that the variable written i the source happens to be a char is irelevant. Paul
