template<int N>
uint64_t shift(uint64_t b) {
if (N > 0)
return b << N;
else
return b >> -N;
}
int main() {
int a = shift<-5>(0x100);
int b = shift<5>(0x100);
return a+b;
}
---
I am using this function template in a header, and other warnings and even
errors tend to get cluttered by the output of bogus "shift count is negative"
warnings. I understand that dead code elimination happens only in the optimizer
and probably to late to see that the negative shift count branch is never
executed, and I could live with that if the warning was controlable with some
"-W" option. Alas, it seems, it is not.
The only way to supress this warning is using "-w", which also inhibits other,
potential useful warnings, so using "-w" everywhere is not really an option.
--
Summary: non controlable bogus warning: right/left shift count is
negative
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: gpiez at web dot de
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44811
