Would the warning generated not suffice? corey On 7/13/05, John Yates <jyates@xxxxxxxxxxx> wrote: > Eljay, > > Though I agree with your point about the standards and > undefined behavior, I do believe that Ulf has identified > a quality of implementation issue. > > Would you not agree that compile-time expression evaluation > should mimic run-time as much as possible? Or to put it > another way, the more often compile-time and run-time > evaluated results diverge, the lower the subject quality > of the compiler. > > If the shift operator at run-time examines only the lower > order 5 bits of the shift count (as Ulf's x86 does) then > a "high-quality" compile-time expression evaluator ought > to do the same. > > /john > > -----Original Message----- > From: Eljay Love-Jensen [mailto:eljay@xxxxxxxxx] > Sent: Tuesday, July 12, 2005 6:46 PM > To: Ulf Magnusson; gcc-help@xxxxxxxxxxx > Subject: Re: Strange shifting behaviour > > > Hi Ulf, > > >When shifting an int by its size in bits... > > That is undefined behavior (implementation dependent), as per C and C++ standards. Ever since C was first taking it's first baby steps. > > By "undefined behavior", that means any given particular implementation can: > + not do anything > + do what you expect > + SEGV > + format your hard drive > > --Eljay > >
