Rollup merge of #102271 - lopopolo:lopopolo/stabilize-duration-try-from-secs-float, r=dtolnay

Stabilize `duration_checked_float`

## Stabilization Report

This stabilization report is for a stabilization of `duration_checked_float`, tracking issue: https://github.com/rust-lang/rust/issues/83400.

### Implementation History

- https://github.com/rust-lang/rust/pull/82179
- https://github.com/rust-lang/rust/pull/90247
- https://github.com/rust-lang/rust/pull/96051
- Changed error type to `FromFloatSecsError` in https://github.com/rust-lang/rust/pull/90247
- https://github.com/rust-lang/rust/pull/96051 changes the rounding mode to round-to-nearest instead of truncate.

## API Summary

This stabilization report proposes the following API to be stabilized in `core`, along with their re-exports in `std`:

```rust
// core::time

impl Duration {
    pub const fn try_from_secs_f32(secs: f32) -> Result<Duration, TryFromFloatSecsError>;
    pub const fn try_from_secs_f64(secs: f64) -> Result<Duration, TryFromFloatSecsError>;
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TryFromFloatSecsError { ... }

impl core::fmt::Display for TryFromFloatSecsError { ... }
impl core::error::Error for TryFromFloatSecsError { ... }
```

These functions are made const unstable under `duration_consts_float`, tracking issue #72440.

There is an open question in the tracking issue around what the error type should be called which I was hoping to resolve in the context of an FCP.

In this stabilization PR, I have altered the name of the error type to `TryFromFloatSecsError`. In my opinion, the error type shares the name of the method (adjusted to accommodate both types of floats), which is consistent with other error types in `core`, `alloc` and `std` like `TryReserveError` and `TryFromIntError`.

## Experience Report

Code such as this is ready to be converted to a checked API to ensure it is panic free:

```rust
impl Time {
    pub fn checked_add_f64(&self, seconds: f64) -> Result<Self, TimeError> {
        // Fail safely during `f64` conversion to duration
        if seconds.is_nan() || seconds.is_infinite() {
            return Err(TzOutOfRangeError::new().into());
        }

        if seconds.is_sign_positive() {
            self.checked_add(Duration::from_secs_f64(seconds))
        } else {
            self.checked_sub(Duration::from_secs_f64(-seconds))
        }
    }
}
```

See: https://github.com/artichoke/artichoke/issues/2194.

`@rustbot` label +T-libs-api -T-libs

cc `@mbartlett21`

2 files changed, 2 insertions, 3 deletions

diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 78838adb8dd..385585dada8 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -280,7 +280,6 @@
 #![feature(core_intrinsics)]
 #![feature(cstr_from_bytes_until_nul)]
 #![feature(cstr_internals)]
-#![feature(duration_checked_float)]
 #![feature(duration_constants)]
 #![feature(error_generic_member_access)]
 #![feature(error_in_core)]
diff --git a/library/std/src/time.rs b/library/std/src/time.rs
index d4a1b9d9b50..34e18b5fa87 100644
--- a/library/std/src/time.rs
+++ b/library/std/src/time.rs
@@ -43,8 +43,8 @@ use crate::sys_common::{FromInner, IntoInner};
 #[stable(feature = "time", since = "1.3.0")]
 pub use core::time::Duration;
 
-#[unstable(feature = "duration_checked_float", issue = "83400")]
-pub use core::time::FromFloatSecsError;
+#[stable(feature = "duration_checked_float", since = "CURRENT_RUSTC_VERSION")]
+pub use core::time::TryFromFloatSecsError;
 
 /// A measurement of a monotonically nondecreasing clock.
 /// Opaque and useful only with [`Duration`].