[Bug c/92857] -Wsign-conversion flag issues false positives for expression using typedef'ed unsigned types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92857 Joshua Saxby changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #5 from Joshua Saxby --- Ah, I have some reading to do, then. Thank you for pointing that out and apologies for wasting your time everyone.
[Bug c/92857] -Wsign-conversion flag issues false positives for expression using typedef'ed unsigned types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92857 --- Comment #4 from Andrew Pinski --- (In reply to Joshua Saxby from comment #2) > (In reply to Richard Biener from comment #1) > > I think the warning is about foo - bar being carried out in type 'int' due > > to > > integer promotion and that converted to size_t which may turn the negative > > result into a positive. > > That could be the issue, although I would expect the integer promotion to > promote to an unsigned integer type rather than a signed one. Am I mistaken > in this assumption? YES you are. If a type is smaller than int and fits into int, then it is prompoted to int (and not unsigned int).
[Bug c/92857] -Wsign-conversion flag issues false positives for expression using typedef'ed unsigned types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92857 --- Comment #3 from Joshua Saxby --- I can confirm that if `MyUnsigned` is changed to `unsigned char`, the issue persists, however if it is changed to `unsigned int`, the issue is not present.
[Bug c/92857] -Wsign-conversion flag issues false positives for expression using typedef'ed unsigned types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92857 --- Comment #2 from Joshua Saxby --- (In reply to Richard Biener from comment #1) > I think the warning is about foo - bar being carried out in type 'int' due to > integer promotion and that converted to size_t which may turn the negative > result into a positive. That could be the issue, although I would expect the integer promotion to promote to an unsigned integer type rather than a signed one. Am I mistaken in this assumption? I don't know if it makes a difference, but if `MyUnsigned` is replaced with `unsigned`, then the warning diagnostic is not issued. Then again, to demonstrate if it is an issue with the integer promotion or not, probably it should be tested with `unsigned char` as well.
[Bug c/92857] -Wsign-conversion flag issues false positives for expression using typedef'ed unsigned types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92857 Richard Biener changed: What|Removed |Added Keywords||diagnostic Known to fail||9.2.0 --- Comment #1 from Richard Biener --- I think the warning is about foo - bar being carried out in type 'int' due to integer promotion and that converted to size_t which may turn the negative result into a positive.
