[Bug libstdc++/95992] chrono adding duration to time_point reports signed integer overflow with -fsanitize=undefined

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95992

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I don't think there's any bug here. Libstdc++ uses nanoseconds for
chrono::system_clock::duration, but libc++ uses microseconds.

If you replace system_clock with high_resolution_clock you get the same error
with both libstdc++ and libc++, and the reason is that 9 billion seconds cannot
be represented in nanoseconds.

You need to use more suitable types for the durations you're trying to deal
with, e.g.

using duration_t = std::chrono::microseconds;

void test() {
    std::chrono::time_point<std::chrono::system_clock, duration_t> tp;