Implement feature `char_to_u32` by okaneco · Pull Request #158940 · rust-lang/rust

okaneco · 2026-07-08T03:32:54Z

Accepted ACP: rust-lang/libs-team#778 (comment)
Tracking issue: #158938

Add method char::to_u32 which returns the underlying value of char.

rustbot · 2026-07-08T03:33:00Z

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hanna-kruppe

Thanks! Just two suggestions for improving the docs. r=me if the first one's done, the second is more speculative so I don't want to block the PR over it.

r? hanna-kruppe

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hanna-kruppe · 2026-07-08T18:58:02Z

        ToCasefold(CaseMappingIter::new(conversions::to_casefold(self)))
    }

+    /// Returns the value of `self` as a `u32`.


The "value of a char as u32" is not necessarily obvious, let's spell out that this returns the code point value (cf. wording in the reference).

Agree, the wording was weak and that's a better suggestion.

Pushed in 77d7cf2

hanna-kruppe · 2026-07-08T19:00:24Z

+    /// let heart = '❤';
+    ///
+    /// assert_eq!(ascii.to_u32(), 97_u32);
+    /// assert_eq!(heart.to_u32(), 0x2764_u32);


Not 100% convinced this is needed, but it might be useful to show off that this is the inverse of char::from_u32 because the number looks completely arbitrary on its own.

assert_eq!(char::from_u32(heart.to_u32()), Some(heart));

(Possibly the round-tripping deserves a separate example with its own introduction.)

I felt like this needed an example but wasn't sure exactly what to write. I can note this in the tracking issue as an area for improvement before stabilization.

hanna-kruppe · 2026-07-08T20:56:41Z

@rustbot author

rustbot · 2026-07-08T20:56:45Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

Add method `char::to_u32` which returns the underlying value of `char`.

hanna-kruppe · 2026-07-09T11:14:02Z

@bors r+ rollup

rust-bors · 2026-07-09T11:14:06Z

📌 Commit 77d7cf2 has been approved by hanna-kruppe

It is now in the queue for this repository.

Implement feature `char_to_u32` Accepted ACP: rust-lang/libs-team#778 (comment) Tracking issue: rust-lang#158938 Add method `char::to_u32` which returns the underlying value of `char`.

…uwer Rollup of 21 pull requests Successful merges: - #150946 (intrinsics: Add a fallback for non-const libm float functions) - #158510 (Enable `static_position_independent_executables` on all gnu and musl targets) - #158541 (Move `std::io::Write` to `core::io`) - #158899 (Fix `unaligned_volatile_store` by removing `MemFlags::UNALIGNED`) - #155429 (Support `u128`/`i128` c-variadic arguments) - #156370 (Reject linked dylib EII default overrides) - #156508 (Infer all anonymous lifetimes in assoc consts as `'static`) - #158617 (allow mGCA const arguments to fall back to anon consts) - #158645 (Fix splat ICEs and ban it in closures) - #158859 (Improve `-Zls` diagnostic message on `.rs` files) - #158988 (Redo `TokenStreamIter`) - #158347 (Improve generic parameters handling for #[diagnostic::on_const]) - #158722 (delegation: do not always inherit `ConstArgHasType` predicates) - #158739 (view-types: HIR lowering) - #158883 (tests: fix enum-match.rs to handle LLVM 23) - #158886 (Add documentation for the `no_std` attribute) - #158940 (Implement feature `char_to_u32`) - #158951 (Merge three `MaxUniverse`s into one) - #158961 (Reapply "LLVM 23: Run AssignGUIDPass in some places") - #158996 ([compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes) - #159005 (Use `as_lang_item` instead of repeatedly matching)

Implement feature `char_to_u32` Accepted ACP: rust-lang/libs-team#778 (comment) Tracking issue: rust-lang#158938 Add method `char::to_u32` which returns the underlying value of `char`.

…uwer Rollup of 24 pull requests Successful merges: - #150946 (intrinsics: Add a fallback for non-const libm float functions) - #158510 (Enable `static_position_independent_executables` on all gnu and musl targets) - #158541 (Move `std::io::Write` to `core::io`) - #158899 (Fix `unaligned_volatile_store` by removing `MemFlags::UNALIGNED`) - #156027 (Consider captured regions for opaque type region liveness.) - #156370 (Reject linked dylib EII default overrides) - #156508 (Infer all anonymous lifetimes in assoc consts as `'static`) - #157561 (rustdoc: do not include extra stuff in span) - #158617 (allow mGCA const arguments to fall back to anon consts) - #158645 (Fix splat ICEs and ban it in closures) - #158859 (Improve `-Zls` diagnostic message on `.rs` files) - #158988 (Redo `TokenStreamIter`) - #158347 (Improve generic parameters handling for #[diagnostic::on_const]) - #158384 (Allow BackwardIncompatibleDropHint in polonius legacy) - #158722 (delegation: do not always inherit `ConstArgHasType` predicates) - #158739 (view-types: HIR lowering) - #158877 (borrowck: Keep returned `path` from `best_blame_constraint()` consistent) - #158883 (tests: fix enum-match.rs to handle LLVM 23) - #158886 (Add documentation for the `no_std` attribute) - #158940 (Implement feature `char_to_u32`) - #158951 (Merge three `MaxUniverse`s into one) - #158961 (Reapply "LLVM 23: Run AssignGUIDPass in some places") - #158995 (Use REST API in linkchecker script) - #158996 ([compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes)

Implement feature `char_to_u32` Accepted ACP: rust-lang/libs-team#778 (comment) Tracking issue: rust-lang#158938 Add method `char::to_u32` which returns the underlying value of `char`.

Rollup of 24 pull requests Successful merges: - #150946 (intrinsics: Add a fallback for non-const libm float functions) - #158541 (Move `std::io::Write` to `core::io`) - #156027 (Consider captured regions for opaque type region liveness.) - #156370 (Reject linked dylib EII default overrides) - #156508 (Infer all anonymous lifetimes in assoc consts as `'static`) - #157561 (rustdoc: do not include extra stuff in span) - #158617 (allow mGCA const arguments to fall back to anon consts) - #158645 (Fix splat ICEs and ban it in closures) - #158859 (Improve `-Zls` diagnostic message on `.rs` files) - #158988 (Redo `TokenStreamIter`) - #158347 (Improve generic parameters handling for #[diagnostic::on_const]) - #158384 (Allow BackwardIncompatibleDropHint in polonius legacy) - #158722 (delegation: do not always inherit `ConstArgHasType` predicates) - #158739 (view-types: HIR lowering) - #158877 (borrowck: Keep returned `path` from `best_blame_constraint()` consistent) - #158883 (tests: fix enum-match.rs to handle LLVM 23) - #158886 (Add documentation for the `no_std` attribute) - #158940 (Implement feature `char_to_u32`) - #158951 (Merge three `MaxUniverse`s into one) - #158960 (Fix bootstrap submodule path prefix matching) - #158961 (Reapply "LLVM 23: Run AssignGUIDPass in some places") - #158995 (Use REST API in linkchecker script) - #158996 ([compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes) - #159036 (bootstrap: expand '@argfile' arguments to rustc shim)

Rollup merge of #158940 - okaneco:char_to_u32, r=hanna-kruppe Implement feature `char_to_u32` Accepted ACP: rust-lang/libs-team#778 (comment) Tracking issue: #158938 Add method `char::to_u32` which returns the underlying value of `char`.

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jul 8, 2026

rustbot assigned JohnTitor Jul 8, 2026

hanna-kruppe approved these changes Jul 8, 2026

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rustbot assigned hanna-kruppe and unassigned JohnTitor Jul 8, 2026

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 8, 2026

Implement feature char_to_u32

77d7cf2

Add method `char::to_u32` which returns the underlying value of `char`.

okaneco force-pushed the char_to_u32 branch from 059fd6a to 77d7cf2 Compare July 9, 2026 09:08

rust-bors Bot 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 9, 2026

JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 18 pull requests #159013

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JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 21 pull requests #159020

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JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 21 pull requests #159024

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JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 24 pull requests #159037

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This was referenced Jul 9, 2026

Rollup of 25 pull requests #159045

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Rollup of 24 pull requests #159046

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rust-bors Bot merged commit 372c7a7 into rust-lang:main Jul 10, 2026
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rustbot added this to the 1.99.0 milestone Jul 10, 2026

okaneco deleted the char_to_u32 branch July 10, 2026 05:38

okaneco mentioned this pull request Jul 10, 2026

Tracking Issue for char_to_u32 #158938

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Implement feature `char_to_u32`#158940

Implement feature `char_to_u32`#158940
rust-bors[bot] merged 1 commit into
rust-lang:mainfrom
okaneco:char_to_u32

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