Stabilize `const_option` #131120

tgross35 · 2024-10-01T21:52:30Z

This makes the following API stable in const contexts:

impl<T> Option<T> {
    pub const fn as_mut(&mut self) -> Option<&mut T>;
    pub const fn expect(self, msg: &str) -> T;
    pub const fn unwrap(self) -> T;
    pub const unsafe fn unwrap_unchecked(self) -> T;
    pub const fn take(&mut self) -> Option<T>;
    pub const fn replace(&mut self, value: T) -> Option<T>;
}

impl<T> Option<&T> {
    pub const fn copied(self) -> Option<T>
    where T: Copy;
}

impl<T> Option<&mut T> {
    pub const fn copied(self) -> Option<T>
    where T: Copy;
}

impl<T, E> Option<Result<T, E>> {
    pub const fn transpose(self) -> Result<Option<T>, E>
}

impl<T> Option<Option<T>> {
    pub const fn flatten(self) -> Option<T>;
}

The following functions make use of the unstable const_precise_live_drops feature:

expect
unwrap
unwrap_unchecked
transpose
flatten

Fixes: #67441

Cc @rust-lang/wg-const-eval

rustbot · 2024-10-01T21:52:39Z

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rustbot · 2024-10-01T21:52:41Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

The Miri subtree was changed

cc @rust-lang/miri

tgross35 · 2024-10-01T22:02:05Z

FCP started today so should complete on the 11th. The beta branch is the same day, so if this gets approved before then, this API will make 1.83.

take and replace need const_replace, which is proposed to be stabilized in #130954. However, there is a chance that const_replace takes longer to stabilize #130954 (comment). If it winds up getting delayed to the following version, we can move take and replace under a new const_option_replace, to be stabilized whenever const_replace merges. (I left todos in the diff related to this).

expect calls panic_display. This seems to be okay because it is only formatting for a single string, similar to const { panic!("foo") }.

RalfJung · 2024-10-02T06:07:42Z

The following functions make use of the unstable
const_precise_live_drops feature:

That's fine from my side.

RalfJung · 2024-10-11T16:21:53Z

library/core/src/option.rs

@@ -1712,7 +1716,9 @@ impl<T> Option<T> {
    /// ```
    #[inline]
    #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_allow_const_fn_unstable(const_replace)] // todo: drop if we don't get stable const_replace


This is still in FCP at #130954, so we have to wait until tomorrow before we can land this PR as-is.

That just merged so I was able to update & drop those gates.

This makes the following API stable in const contexts: impl<T> Option<T> { pub const fn as_mut(&mut self) -> Option<&mut T>; pub const fn expect(self, msg: &str) -> T; pub const fn unwrap(self) -> T; pub const unsafe fn unwrap_unchecked(self) -> T; pub const fn take(&mut self) -> Option<T>; pub const fn replace(&mut self, value: T) -> Option<T>; } impl<T> Option<&T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T> Option<&mut T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T, E> Option<Result<T, E>> { pub const fn transpose(self) -> Result<Option<T>, E> } impl<T> Option<Option<T>> { pub const fn flatten(self) -> Option<T>; } The following functions make use of the unstable `const_precise_live_drops` feature: - `expect` - `unwrap` - `unwrap_unchecked` - `transpose` - `flatten` Fixes: <rust-lang#67441>

tgross35 · 2024-10-12T21:10:27Z

FCP complete at #67441 (comment). const_replace also merged so nothing here is blocked on that anymore.

RalfJung · 2024-10-12T21:15:32Z

Looks great :) @bors r+ rollup

bors · 2024-10-12T21:15:36Z

📌 Commit 19f6c17 has been approved by RalfJung

It is now in the queue for this repository.

…=RalfJung Stabilize `const_option` This makes the following API stable in const contexts: ```rust impl<T> Option<T> { pub const fn as_mut(&mut self) -> Option<&mut T>; pub const fn expect(self, msg: &str) -> T; pub const fn unwrap(self) -> T; pub const unsafe fn unwrap_unchecked(self) -> T; pub const fn take(&mut self) -> Option<T>; pub const fn replace(&mut self, value: T) -> Option<T>; } impl<T> Option<&T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T> Option<&mut T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T, E> Option<Result<T, E>> { pub const fn transpose(self) -> Result<Option<T>, E> } impl<T> Option<Option<T>> { pub const fn flatten(self) -> Option<T>; } ``` The following functions make use of the unstable `const_precise_live_drops` feature: - `expect` - `unwrap` - `unwrap_unchecked` - `transpose` - `flatten` Fixes: <rust-lang#67441>

Rollup of 7 pull requests Successful merges: - rust-lang#131120 (Stabilize `const_option`) - rust-lang#131207 (ci: aarch64-gnu-debug job) - rust-lang#131334 (Enable sanitizers for loongarch64-unknown-*) - rust-lang#131358 (force "HEAD" for non-CI and `git_upstream_merge_base` for CI environment) - rust-lang#131418 (Use throw intrinsic from stdarch in wasm libunwind) - rust-lang#131579 (Remap path prefix in the panic message of `tests/ui/meta/revision-bad.rs`) - rust-lang#131591 (add latest crash tests) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 7 pull requests Successful merges: - rust-lang#131120 (Stabilize `const_option`) - rust-lang#131334 (Enable sanitizers for loongarch64-unknown-*) - rust-lang#131358 (force "HEAD" for non-CI and `git_upstream_merge_base` for CI environment) - rust-lang#131418 (Use throw intrinsic from stdarch in wasm libunwind) - rust-lang#131579 (Remap path prefix in the panic message of `tests/ui/meta/revision-bad.rs`) - rust-lang#131591 (add latest crash tests) - rust-lang#131626 (remove a couple of redundant String to String conversion) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#131120 - tgross35:stabilize-const_option, r=RalfJung Stabilize `const_option` This makes the following API stable in const contexts: ```rust impl<T> Option<T> { pub const fn as_mut(&mut self) -> Option<&mut T>; pub const fn expect(self, msg: &str) -> T; pub const fn unwrap(self) -> T; pub const unsafe fn unwrap_unchecked(self) -> T; pub const fn take(&mut self) -> Option<T>; pub const fn replace(&mut self, value: T) -> Option<T>; } impl<T> Option<&T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T> Option<&mut T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T, E> Option<Result<T, E>> { pub const fn transpose(self) -> Result<Option<T>, E> } impl<T> Option<Option<T>> { pub const fn flatten(self) -> Option<T>; } ``` The following functions make use of the unstable `const_precise_live_drops` feature: - `expect` - `unwrap` - `unwrap_unchecked` - `transpose` - `flatten` Fixes: <rust-lang#67441>

tgross35 · 2024-10-13T17:58:30Z

It looks like this may have made the version cutoff after all 🎉 lucky us that a LLVM bump delayed #131560

…=RalfJung Stabilize `const_option` This makes the following API stable in const contexts: ```rust impl<T> Option<T> { pub const fn as_mut(&mut self) -> Option<&mut T>; pub const fn expect(self, msg: &str) -> T; pub const fn unwrap(self) -> T; pub const unsafe fn unwrap_unchecked(self) -> T; pub const fn take(&mut self) -> Option<T>; pub const fn replace(&mut self, value: T) -> Option<T>; } impl<T> Option<&T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T> Option<&mut T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T, E> Option<Result<T, E>> { pub const fn transpose(self) -> Result<Option<T>, E> } impl<T> Option<Option<T>> { pub const fn flatten(self) -> Option<T>; } ``` The following functions make use of the unstable `const_precise_live_drops` feature: - `expect` - `unwrap` - `unwrap_unchecked` - `transpose` - `flatten` Fixes: <rust-lang#67441>

rustbot assigned scottmcm Oct 1, 2024

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Oct 1, 2024

tgross35 added the S-waiting-on-fcp Status: PR is in FCP and is awaiting for FCP to complete. label Oct 1, 2024

tgross35 mentioned this pull request Oct 1, 2024

Tracking issue for const Option functions #67441

Closed

RalfJung reviewed Oct 11, 2024

View reviewed changes

tgross35 force-pushed the stabilize-const_option branch from 5af32ad to 19f6c17 Compare October 12, 2024 21:07

tgross35 removed the S-waiting-on-fcp Status: PR is in FCP and is awaiting for FCP to complete. label Oct 12, 2024

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 Oct 12, 2024

tgross35 mentioned this pull request Oct 12, 2024

Rollup of 7 pull requests #131630

Closed

tgross35 mentioned this pull request Oct 13, 2024

Rollup of 7 pull requests #131635

Merged

bors merged commit c8b2f7e into rust-lang:master Oct 13, 2024
6 checks passed

rustbot added this to the 1.83.0 milestone Oct 13, 2024

tgross35 deleted the stabilize-const_option branch October 13, 2024 06:27

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