Implementation of try_from_{nanos_u128,mins,hours,days,weeks}

[Zorbatron]

Implements the methods discussed in the related ACP.

impl Duration {
    pub const fn try_from_nanos_u128(nanos: u64) -> Result<Duration, DurationConversionError>;
    pub const fn try_from_weeks(weeks: u64) -> Result<Duration, DurationConversionError>;
    pub const fn try_from_days(days: u64) -> Result<Duration, DurationConversionError>;
    pub const fn try_from_hours(hours: u64) -> Result<Duration, DurationConversionError>;
    pub const fn try_from_mins(mins: u64) -> Result<Duration, DurationConversionError>;
}

ACP: rust-lang/libs-team#749
Tracking issue: #153678

[rustbot]

r? @scottmcm

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[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[Zorbatron]

@scottmcm, sorry for the ping if I'm missing something for this PR to be reviewed, but it's been over a month. Are you available to look this over?

[teor2345]

The code here looks good, I have a question about the stability of the error and display impls. (Probably for the libs-api team to answer.)

View changes since this review

[teor2345]

I think removing the Error and Display impls from TryFromFloatSecsError is a breaking change?
https://doc.rust-lang.org/std/time/struct.TryFromFloatSecsError.html#impl-Error-for-TryFromFloatSecsError

Maybe it's worth asking if DurationConversionError and its trait impls should be stabilised instead?
rust-lang/libs-team#749 (comment)

Here's the context from the meeting notes approving the ACP:
https://hackmd.io/rGWrzOppS8-ehldMMjWwKQ#new-change-proposal-rusttflibs749-ACP-Add-non-panicking-versions-of-Durationfrom_nanos_u128minshoursdaysweeks

Suddenly not being able to print the return type of the stable try_from_secs_f64() method seems surprising for users. So does having to name it using a stable alias that doesn't appear in the method docs.