Make some methods of `Pin` unstable const #76655

CDirkx · 2020-09-12T23:58:10Z

Make the following methods unstable const under the const_pin feature:

new
new_unchecked
into_inner
into_inner_unchecked
get_ref
into_ref
get_mut
get_unchecked_mut

Of these, into_inner and into_inner_unchecked require the unstable const_precise_live_drops.

Also adds tests for these methods in a const context.

Tracking issue: #76654

Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654

CDirkx · 2020-09-13T00:03:48Z

I remember checking if Pin methods could be made const before, however at that time I got an error that const fns could only be inside impl blocks that have Sized or no bounds on generic parameters. I couldn't find what enabled this?

CDirkx · 2020-09-13T00:11:36Z

I excluded into_ref (implemented on on Pin<&mut T>), which could technically also be made const, as &mut in consts is still being figured out I believe.

ecstatic-morse · 2020-09-13T00:44:06Z

I remember checking if Pin methods could be made const before, however at that time I got an error that const fns could only be inside impl blocks that have Sized or no bounds on generic parameters. I couldn't find what enabled this?

This is currently part of the "min const fn" checks, which are disabled for const-unstable functions. Presumably you used ~~rustc_const_unstable~~ rustc_const_stable the last time you tried this.

I excluded into_ref (implemented on on Pin<&mut T>), which could technically also be made const, as &mut in consts is still being figured out I believe.

I don't really see a reason to exclude this if it compiles. As long as these functions are all const-unstable, there's not really any risk.

cc @rust-lang/wg-const-eval Unlike Option and Result, I doubt Pin is useful in a const-context. However, making these unstably const might allow people to test things like const-qualification more thoroughly, and I don't see any downsides.

CDirkx · 2020-09-13T01:34:02Z

I added the methods into_ref, get_mut, get_unchecked_mut from Pin<&mut T>, the tests for these are a bit different.

RalfJung · 2020-09-13T11:44:05Z

library/core/tests/pin.rs

+        // test that the methods of `Pin<&mut T>` are usable in a const context
+        // should be written as the other tests once `&mut` is usable in constants


Are these two sentences? I think they are. If yes, please add capitalization and .. I had to read this 5 times to successfully parse it.

ecstatic-morse · 2020-09-15T20:49:53Z

r=me with Ralf's change.

@bors delegate

bors · 2020-09-15T20:49:57Z

✌️ @CDirkx can now approve this pull request

Make the following methods unstable const under the `const_pin` feature: - `into_ref` - `get_mut` - `get_unchecked_mut`

CDirkx · 2020-09-18T17:28:48Z

r=@ecstatic-morse

RalfJung · 2020-09-18T17:29:43Z

Almost, the right command is

@bors r=ecstatic-morse

bors · 2020-09-18T17:29:44Z

📌 Commit e3c6e46 has been approved by ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

@ecstatic-morse

Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: rust-lang#76654 r? @ecstatic-morse

…atic-morse Rollup of 13 pull requests Successful merges: - rust-lang#72734 (Reduce duplicate in liballoc reserve error handling) - rust-lang#76131 (Don't use `zip` to compare iterators during pretty-print hack) - rust-lang#76150 (Don't recommend ManuallyDrop to customize drop order) - rust-lang#76275 (Implementation of Write for some immutable ref structs) - rust-lang#76489 (Add explanation for E0756) - rust-lang#76581 (do not ICE on bound variables, return `TooGeneric` instead) - rust-lang#76655 (Make some methods of `Pin` unstable const) - rust-lang#76783 (Only get ImplKind::Impl once) - rust-lang#76807 (Use const-checking to forbid use of unstable features in const-stable functions) - rust-lang#76888 (use if let instead of single match arm expressions) - rust-lang#76914 (extend `Ty` and `TyCtxt` lints to self types) - rust-lang#77022 (Reduce boilerplate for BytePos and CharPos) - rust-lang#77032 (lint missing docs for extern items) Failed merges: r? `@ghost`

rust-highfive assigned ecstatic-morse Sep 12, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Sep 12, 2020

jyn514 added A-const-fn T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Sep 13, 2020

ecstatic-morse mentioned this pull request Sep 13, 2020

Tracking issue for const Pin methods #76654

Closed

CDirkx force-pushed the const-pin branch from ac31fbb to 730f048 Compare September 13, 2020 01:32

RalfJung reviewed Sep 13, 2020

View reviewed changes

Make some methods of Pin<&mut T> unstable const

e3c6e46

Make the following methods unstable const under the `const_pin` feature: - `into_ref` - `get_mut` - `get_unchecked_mut`

CDirkx force-pushed the const-pin branch from 730f048 to e3c6e46 Compare September 18, 2020 17:27

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 18, 2020

Dylan-DPC-zz mentioned this pull request Sep 19, 2020

Rollup of 17 pull requests #76944

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Dylan-DPC-zz mentioned this pull request Sep 19, 2020

Rollup of 18 pull requests #76945

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Dylan-DPC-zz mentioned this pull request Sep 19, 2020

Rollup of 18 pull requests #76946

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Dylan-DPC-zz mentioned this pull request Sep 20, 2020

Rollup of 12 pull requests #76951

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Dylan-DPC-zz mentioned this pull request Sep 21, 2020

Rollup of 14 pull requests #76987

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Dylan-DPC-zz mentioned this pull request Sep 21, 2020

Rollup of 17 pull requests #76988

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Dylan-DPC-zz mentioned this pull request Sep 22, 2020

Rollup of 13 pull requests #77038

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ecstatic-morse mentioned this pull request Sep 22, 2020

Rollup of 13 pull requests #77039

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ecstatic-morse mentioned this pull request Sep 22, 2020

Rollup of 13 pull requests #77040

Closed

bors merged commit 537ede4 into rust-lang:master Sep 22, 2020

rustbot added this to the 1.48.0 milestone Sep 22, 2020

CDirkx deleted the const-pin branch September 23, 2020 19:23

RalfJung added the A-const-eval Area: Constant evaluation, covers all const contexts (static, const fn, ...) label Dec 1, 2024

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Make some methods of `Pin` unstable const #76655

Make some methods of `Pin` unstable const #76655

CDirkx commented Sep 12, 2020 •

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CDirkx commented Sep 13, 2020

CDirkx commented Sep 13, 2020

ecstatic-morse commented Sep 13, 2020 •

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CDirkx commented Sep 13, 2020

RalfJung Sep 13, 2020

ecstatic-morse commented Sep 15, 2020

bors commented Sep 15, 2020

CDirkx commented Sep 18, 2020

RalfJung commented Sep 18, 2020

bors commented Sep 18, 2020

		// test that the methods of `Pin<&mut T>` are usable in a const context
		// should be written as the other tests once `&mut` is usable in constants

Make some methods of Pin unstable const #76655

Make some methods of Pin unstable const #76655

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CDirkx commented Sep 12, 2020 • edited Loading

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ecstatic-morse commented Sep 15, 2020

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bors commented Sep 18, 2020

Make some methods of `Pin` unstable const #76655

Make some methods of `Pin` unstable const #76655

CDirkx commented Sep 12, 2020 •

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ecstatic-morse commented Sep 13, 2020 •

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