impl Arbitrary for SystemTime #178
Conversation
caspermeijn
force-pushed
the
system_time
branch
from
9d917ef
to
4e1033b
Compare
| fn arbitrary(u: &mut Unstructured<'a>) -> Result<Self> { | ||
| // Create a SystemTime by adding or subtracting a duration from epoch. | ||
| // The result is not guaranteed to fit. Keep trying until a good SystemTime if found. | ||
| loop { |
There was a problem hiding this comment.
It seems unfortunate to have behaviour of this that is dependent on the target, but since the underlying type requires it, why not #[cfg] or even just check at runtime if the platform considers UNIX_EPOCH the minimal representable timestamp and just not bother with the add/sub on those targets?
Would save on the input bytes and such.
There was a problem hiding this comment.
The docs for SystemTime don't guarantee anything regarding what fits in a SystemTime. So I would not know what to check for. Maybe UNIX_EPOCH is the minimum. Maybe the year 0 is the minimum.
Also, the maximum is interesting. It is not guaranteed that SystemTime::UNIX_EPOCH + Duration::MAX will fit. Therefore, it needs to be checked.
I could determine the minimum and maximum by trail and error, save this result and use that to make sure we never generate a value that doesn't fit. But that isn't great code as well.
There was a problem hiding this comment.
UNIX_EPOCH.checked_sub(Duration::from_nanos(1)).is_none() implies that UNIX_EPOCH is the min value representable. This could be checked once and saved in a static or somesuch.
Unfortunately I've no good ideas for the maximum, so yeah, you would need the loop regardless. Feel free to ignore the comment until others chime in.
No description provided.