https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96570
Bug ID: 96570 Summary: Warnings desired for time_t to int coversions Product: gcc Version: 10.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: terra at gnome dot org Target Milestone: --- This is a wishlist item. It's filed for C++ but would apply to C too. It would be useful to have some mechanism to cause warnings to be emitted at compile-time when values of type time_t are cut down in size. For example: int now = time(nullptr); // Not good! int now = int(time(nullptr)); // Not good! // (This one occurs not only when someone wanted the compiler to shut up, // but also occurs when using casts to resolve overload resolution.) void foo(int); ... time_t now = time(nullptr); foo(now); // Not good Note: this is desired for explicit casts too. Hence -Wconversion in its current form is not what I am looking for. I am not sure how, if at all, the warnings should be suppressed, but a cast via a 64-bit type, int(int64_t(time(null))), is an option.