Tracking Issue for constify-ing non-trait `Duration` methods #72440

marmeladema · 2020-05-21T22:30:07Z

This is a tracking issue for constify-ing non-trait Duration methods

The feature gates for the issue are #![feature(duration_consts_2)] (stabilized in rust 1.58.0) and #![feature(duration_consts_float)] (still unstable).

The following methods will effectively be made const under the duration_consts_2 feature:

Duration::new [stable since 1.58.0]
Duration::checked_add [stable since 1.58.0]
Duration::saturating_add [stable since 1.58.0]
Duration::checked_sub [stable since 1.58.0]
Duration::saturating_sub [stable since 1.58.0]
Duration::checked_mul [stable since 1.58.0]
Duration::saturating_mul [stable since 1.58.0]
Duration::checked_div [stable since 1.58.0]

The following methods will effectively be made const under the duration_consts_float feature:

Duration::as_secs_f64 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::as_secs_f32[stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::div_duration_f64 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::div_duration_f32 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::from_secs_f64 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::from_secs_f32 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::mul_f64 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::mul_f32 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::div_f64 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]
Duration::div_f32 [stabilization blocked by Tracking issue for #![feature(const_fn_floating_point_arithmetic)] #57241]

Steps

Adjust documentation (see instructions on rustc-dev-guide)
Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

XXX --- list all the "unresolved questions" found in the RFC to ensure they are
not forgotten

Implementation history

Constify most non-trait Duration methods as described: Constify most non-trait Duration methods as described in #72440 #72481
Make all methods of Duration unstably const: Make all methods of Duration unstably const #76335
Partially stabilize duration_consts_2: Partially stabilize duration_consts_2 #89542

The text was updated successfully, but these errors were encountered:

marmeladema · 2020-05-21T22:33:13Z

I also would like to add a Duration::MAX associated const. Should it be part of the same tracking issue?

Mark-Simulacrum · 2020-05-21T22:52:47Z

I don't think so -- adding a new constant seems pretty orthogonal to me.

marmeladema · 2020-05-22T07:26:18Z

I don't think so -- adding a new constant seems pretty orthogonal to me.

It's orthogonal but depends on Duration::new being const so I thought having a tracking issue just for one associated const might be overkill.

RalfJung · 2020-05-22T20:03:26Z

Because they end up calling f32|64::is_finite which ultimately call mem::transmute which is not const.

FWIW, #72449 makes the other safe transmute wrappers const. Once that lands, abs_private and is_finite could also be made const.

RalfJung · 2020-05-23T17:43:45Z

All right, #72449 will make is_finite const as well, so you should be able to use that.

marmeladema · 2020-05-23T17:47:37Z

Great! I'll wait for #72449 to land and update my PR accordingly.

…72440

RalfJung · 2020-05-30T15:06:37Z

The tracking issue should also notice that stabilizing any of the f32/f64 methods is blocked on stabilizing floating point in const at all (#57241).

…i-obk Constify most non-trait `Duration` methods as described in rust-lang#72440 The remaining methods could probably be made const once rust-lang#72449 lands with support for `f<32|64>::is_finite()`.

…72440

Constify most non-trait `Duration` methods as described in rust-lang#72440 The remaining methods could probably be made const once rust-lang#72449 lands with support for `f<32|64>::is_finite()`.

Make the following methods of `Duration` unstable const under `duration_const_2`: - `from_secs_f64` - `from_secs_f32` - `mul_f64` - `mul_f32` - `div_f64` - `div_f32` This results in all methods of `Duration` being (unstable) const. Also adds tests for these methods in a const context, moved the test to `library` as part of rust-lang#76268. Possible because of rust-lang#72449, which made the relevant `f32` and `f64` methods const. Tracking issue: rust-lang#72440

@ecstatic-morse

…orse Make all methods of `Duration` unstably const Make the following methods of `Duration` unstable const under `duration_const_2`: - `from_secs_f64` - `from_secs_f32` - `mul_f64` - `mul_f32` - `div_f64` - `div_f32` This results in all methods of `Duration` being (unstable) const. Moved the tests to `library` as part of rust-lang#76268. Possible because of rust-lang#72449, which made the relevant `f32` and `f64` methods const. Tracking issue: rust-lang#72440 r? @ecstatic-morse

@ecstatic-morse

…orse Make all methods of `Duration` unstably const Make the following methods of `Duration` unstable const under `duration_const_2`: - `from_secs_f64` - `from_secs_f32` - `mul_f64` - `mul_f32` - `div_f64` - `div_f32` This results in all methods of `Duration` being (unstable) const. Moved the tests to `library` as part of rust-lang#76268. Possible because of rust-lang#72449, which made the relevant `f32` and `f64` methods const. Tracking issue: rust-lang#72440 r? @ecstatic-morse

@ecstatic-morse

…orse Make all methods of `Duration` unstably const Make the following methods of `Duration` unstable const under `duration_const_2`: - `from_secs_f64` - `from_secs_f32` - `mul_f64` - `mul_f32` - `div_f64` - `div_f32` This results in all methods of `Duration` being (unstable) const. Moved the tests to `library` as part of rust-lang#76268. Possible because of rust-lang#72449, which made the relevant `f32` and `f64` methods const. Tracking issue: rust-lang#72440 r? @ecstatic-morse

@ecstatic-morse

…orse Make all methods of `Duration` unstably const Make the following methods of `Duration` unstable const under `duration_const_2`: - `from_secs_f64` - `from_secs_f32` - `mul_f64` - `mul_f32` - `div_f64` - `div_f32` This results in all methods of `Duration` being (unstable) const. Moved the tests to `library` as part of rust-lang#76268. Possible because of rust-lang#72449, which made the relevant `f32` and `f64` methods const. Tracking issue: rust-lang#72440 r? @ecstatic-morse

@ecstatic-morse

…orse Make all methods of `Duration` unstably const Make the following methods of `Duration` unstable const under `duration_const_2`: - `from_secs_f64` - `from_secs_f32` - `mul_f64` - `mul_f32` - `div_f64` - `div_f32` This results in all methods of `Duration` being (unstable) const. Moved the tests to `library` as part of rust-lang#76268. Possible because of rust-lang#72449, which made the relevant `f32` and `f64` methods const. Tracking issue: rust-lang#72440 r? @ecstatic-morse

jhpratt · 2021-10-05T03:11:50Z

PR stabilizing non-float methods is up: #89542

…on-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: rust-lang#83400. ### Implementation History - rust-lang#82179 - rust-lang#90247 - rust-lang#96051 - Changed error type to `FromFloatSecsError` in rust-lang#90247 - rust-lang#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 rust-lang#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: artichoke/artichoke#2194. `@rustbot` label +T-libs-api -T-libs cc `@mbartlett21`

…on-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: rust-lang#83400. ### Implementation History - rust-lang#82179 - rust-lang#90247 - rust-lang#96051 - Changed error type to `FromFloatSecsError` in rust-lang#90247 - rust-lang#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 rust-lang#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: artichoke/artichoke#2194. ``@rustbot`` label +T-libs-api -T-libs cc ``@mbartlett21``

MoSal · 2023-04-27T20:04:33Z

Didn't see this mentioned anywhere with a quick search, but Duration::from_secs_f64 is not const anymore?

Is #![feature(duration_consts_float)] no-op now?

MoSal · 2023-04-29T13:11:15Z

Didn't see this mentioned anywhere with a quick search, but Duration::from_secs_f64 is not const anymore?

Is #![feature(duration_consts_float)] no-op now?

Looking at this closer today, the from_* and try_from_* float functions were no longer
const after #110393. That's because the try_from_secs macro makes use of $int_ty::from($expr), the trait impls of which are no longer const.

The from calls can be replaced with ($expr as $int_ty) if it is desired to restore the const impls.

…, r=scottmcm Implement `Duration::as_millis_{f64,f32}` Implementation of rust-lang#122451. Linked const-unstability to rust-lang#72440, so the post there should probably be updated to mentions the 2 new methods when/if this PR is merged.

Rollup merge of rust-lang#122479 - GrigorenkoPV:duration_millis_float, r=scottmcm Implement `Duration::as_millis_{f64,f32}` Implementation of rust-lang#122451. Linked const-unstability to rust-lang#72440, so the post there should probably be updated to mentions the 2 new methods when/if this PR is merged.

marmeladema added the C-tracking-issue Category: A tracking issue for an RFC or an unstable feature. label May 21, 2020

jonas-schievink added A-const-fn Area: const fn foo(..) {..}. Pure functions which can be applied at compile time. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels May 21, 2020

RalfJung mentioned this issue May 22, 2020

Const floating point bitcasts and classification #72449

Merged

marmeladema added a commit to marmeladema/rust that referenced this issue May 30, 2020

Constify most non-trait Duration methods as described in rust-lang#…

7527409

…72440

marmeladema changed the title ~~Tracking Issue for constify-ing most non-trait Duration methods~~ Tracking Issue for constify-ing non-trait Duration methods May 30, 2020

Dylan-DPC-zz mentioned this issue Jul 14, 2020

Rollup of 11 pull requests #74322

Closed

Manishearth mentioned this issue Jul 14, 2020

Rollup of 15 pull requests #74329

Closed

marmeladema added a commit to marmeladema/rust that referenced this issue Jul 15, 2020

Constify most non-trait Duration methods as described in rust-lang#…

4a96800

…72440

KodrAus added the Libs-Tracked Libs issues that are tracked on the team's project board. label Jul 29, 2020

CDirkx mentioned this issue Sep 4, 2020

Make all methods of Duration unstably const #76335

Merged

mark-i-m mentioned this issue Dec 6, 2020

Meta tracking issue for const fn #57563

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KodrAus added the A-time Area: Time label Jan 6, 2021

lopopolo mentioned this issue Sep 25, 2022

Stabilize duration_checked_float #102271

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GrigorenkoPV mentioned this issue Mar 14, 2024

Implement Duration::as_millis_{f64,f32} #122479

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Tracking Issue for constify-ing non-trait `Duration` methods #72440

Tracking Issue for constify-ing non-trait `Duration` methods #72440

marmeladema commented May 21, 2020 •

edited

marmeladema commented May 21, 2020

Mark-Simulacrum commented May 21, 2020

marmeladema commented May 22, 2020

RalfJung commented May 22, 2020 •

edited

RalfJung commented May 23, 2020

marmeladema commented May 23, 2020

RalfJung commented May 30, 2020

jhpratt commented Oct 5, 2021

MoSal commented Apr 27, 2023

MoSal commented Apr 29, 2023

Tracking Issue for constify-ing non-trait Duration methods #72440

Tracking Issue for constify-ing non-trait Duration methods #72440

Comments

marmeladema commented May 21, 2020 • edited

Steps

Unresolved Questions

Implementation history

marmeladema commented May 21, 2020

Mark-Simulacrum commented May 21, 2020

marmeladema commented May 22, 2020

RalfJung commented May 22, 2020 • edited

RalfJung commented May 23, 2020

marmeladema commented May 23, 2020

RalfJung commented May 30, 2020

jhpratt commented Oct 5, 2021

MoSal commented Apr 27, 2023

MoSal commented Apr 29, 2023

Tracking Issue for constify-ing non-trait `Duration` methods #72440

Tracking Issue for constify-ing non-trait `Duration` methods #72440

marmeladema commented May 21, 2020 •

edited

RalfJung commented May 22, 2020 •

edited