Frank Mehnert <Frank.Mehnert@xxxxxxx> writes: > consider the following case: > > uint32_t foo, bar; > ... > foo = bar << 20; > > Of course, this operation can overflow and warning about this > probably does not make sense as the programmer should be aware > of this case. However, a warning in the following case could be > appropriate IMO: > > uint32_t bar; > uint64_t foo; > ... > foo = bar << 20; > > The intension is to catch the overflow case, therefore the > assignment to a 64-bit variable. The intended code would be > > uint32_t bar; > uint64_t foo; > ... > foo = (uint64_t)bar << 20; > > I think it would be a big help if gcc could warn in the 2nd case. > > What do you think? Or is such a warning already available? I'm > a big fan of -Wlogical-op which catches suspicious uses of certain > logical operations... As far as I know there is no current warning in gcc for this kind of case. gcc can warn about cases where a conversion may alter a value, but that is not happening here. The warning here would be something like an implicit widening conversion happens after an arithmetic operation. This seems like a reasonable warning to me. Would you mind opening a feature request at http://gcc.gnu.org/bugzilla/ ? Thanks. Ian
