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Stabilize const char convert - #102470

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est31:stabilize_const_char_convert
Nov 15, 2022
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Stabilize const char convert#102470
bors merged 2 commits into
rust-lang:masterfrom
est31:stabilize_const_char_convert

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@est31

@est31est31 commented Sep 29, 2022•
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Split out const_char_from_u32_unchecked from const_char_convert and stabilize the rest, i.e. stabilize the following functions:

implchar{pubconstfnfrom_u32(self,i:u32) -> Option<char>;pubconstfnfrom_digit(self,num:u32,radix:u32) -> Option<char>;pubconstfnto_digit(self,radix:u32) -> Option<u32>;}// Available through core::char and std::charmod char {pubconstfnfrom_u32(i:u32) -> Option<char>;pubconstfnfrom_digit(num:u32,radix:u32) -> Option<char>;}

And put the following under the from_u32_unchecked const stability gate as it needs Option::unwrap which isn't const-stable (yet):

implchar{pubconstunsafefnfrom_u32_unchecked(i:u32) -> char;}// Available through core::char and std::charmod char {pubconstunsafefnfrom_u32_unchecked(i:u32) -> char;}

cc the tracking issue #89259 (which I'd like to keep open for const_char_from_u32_unchecked).

@est31
Split out from_u32_unchecked from const_char_convert
12c15a2
It relies on the Option::unwrap function which is not const-stable (yet).
@est31
Stabilize const_char_convert
176c44c
@rustbotrustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Sep 29, 2022
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rustbot commented Sep 29, 2022

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Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

  • Stabilizing library features
  • Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
  • Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
  • Changing public documentation in ways that create new stability guarantees
  • Changing observable runtime behavior of library APIs

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rust-highfive commented Sep 29, 2022

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r? @scottmcm

(rust-highfive has picked a reviewer for you, use r? to override)

@rust-highfiverust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Sep 29, 2022
@est31

est31 commented Sep 29, 2022

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I'd like to have an FCP for the stabilization, ideally here because I'd like to re-use the tracking issue. I've opened #89258 12 months ago, and it's been merged 10 months ago, so the feature had plenty of time in nightly.

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

@rustbotrustbot added T-libs-api [DEPRECATED; DO NOT USE] and removed T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Sep 29, 2022
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@est31

est31 commented Oct 6, 2022

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r? rust-lang/libs-api

@scottmcm

scottmcm commented Oct 6, 2022

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There's no group for libs-api, so I (got ddg to) flip a coin, and it came up
r? @joshtriplett

@joshtriplett

joshtriplett commented Oct 14, 2022

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Seems reasonable to me!

@rfcbot merge

@rfcbot

rfcbot commented Oct 14, 2022•
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Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

@rfcbotrfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Oct 14, 2022
@rfcbotrfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Oct 25, 2022
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🔔 This is now entering its final comment period, as per the review above. 🔔

@rfcbotrfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Nov 4, 2022
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The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

@rfcbotrfcbot added the to-announce Announce this issue on triage meeting label Nov 4, 2022
@est31

est31 commented Nov 14, 2022

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r? @joshtriplett it's ready for approval now that the FCP has passed :)

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Could not assign reviewer from: joshtriplett.
User(s) joshtriplett are either the PR author or are already assigned, and there are no other candidates.
Use r? to specify someone else to assign.

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joshtriplett commented Nov 14, 2022

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@bors r+ rollup

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bors commented Nov 14, 2022

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📌 Commit 176c44c has been approved by joshtriplett

It is now in the queue for this repository.

@borsbors 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 Nov 14, 2022
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Nov 14, 2022
@matthiaskrgr
Rollup merge ofrust-lang#102470- est31:stabilize_const_char_convert…
ab87c4c
…, r=joshtriplett
Stabilize const char convert
Split out `const_char_from_u32_unchecked` from `const_char_convert` and stabilize the rest, i.e. stabilize the following functions:
```Rust
impl char {
pub const fn from_u32(self, i: u32) -> Option<char>;
pub const fn from_digit(self, num: u32, radix: u32) -> Option<char>;
pub const fn to_digit(self, radix: u32) -> Option<u32>;
}
// Available through core::char and std::char
mod char {
pub const fn from_u32(i: u32) -> Option<char>;
pub const fn from_digit(num: u32, radix: u32) -> Option<char>;
}
```
And put the following under the `from_u32_unchecked` const stability gate as it needs `Option::unwrap` which isn't const-stable (yet):
```Rust
impl char {
pub const unsafe fn from_u32_unchecked(i: u32) -> char;
}
// Available through core::char and std::char
mod char {
pub const unsafe fn from_u32_unchecked(i: u32) -> char;
}
```
cc the tracking issue rust-lang#89259 (which I'd like to keep open for `const_char_from_u32_unchecked`).
@matthiaskrgrmatthiaskrgr mentioned this pull request Nov 14, 2022
Closed
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Nov 14, 2022
@matthiaskrgr
Rollup merge ofrust-lang#102470- est31:stabilize_const_char_convert…
749ecab
…, r=joshtriplett
Stabilize const char convert
Split out `const_char_from_u32_unchecked` from `const_char_convert` and stabilize the rest, i.e. stabilize the following functions:
```Rust
impl char {
pub const fn from_u32(self, i: u32) -> Option<char>;
pub const fn from_digit(self, num: u32, radix: u32) -> Option<char>;
pub const fn to_digit(self, radix: u32) -> Option<u32>;
}
// Available through core::char and std::char
mod char {
pub const fn from_u32(i: u32) -> Option<char>;
pub const fn from_digit(num: u32, radix: u32) -> Option<char>;
}
```
And put the following under the `from_u32_unchecked` const stability gate as it needs `Option::unwrap` which isn't const-stable (yet):
```Rust
impl char {
pub const unsafe fn from_u32_unchecked(i: u32) -> char;
}
// Available through core::char and std::char
mod char {
pub const unsafe fn from_u32_unchecked(i: u32) -> char;
}
```
cc the tracking issue rust-lang#89259 (which I'd like to keep open for `const_char_from_u32_unchecked`).
@matthiaskrgrmatthiaskrgr mentioned this pull request Nov 14, 2022
Closed
@matthiaskrgrmatthiaskrgr mentioned this pull request Nov 14, 2022
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Nov 15, 2022
@bors
Auto merge ofrust-lang#104418- matthiaskrgr:rollup-y4i6xjc, r=matth…
101e182
…iaskrgr
Rollup of 11 pull requests
Successful merges:
- rust-lang#101967 (Move `unix_socket_abstract` feature API to `SocketAddrExt`.)
- rust-lang#102470 (Stabilize const char convert)
- rust-lang#104223 (Recover from function pointer types with generic parameter list)
- rust-lang#104229 (Don't print full paths in overlap errors)
- rust-lang#104294 (Don't ICE with inline const errors during MIR build)
- rust-lang#104332 (Fixed some `_i32` notation in `maybe_uninit`’s doc)
- rust-lang#104349 (fix some typos in comments)
- rust-lang#104350 (Fix x finding Python on Windows)
- rust-lang#104356 (interpret: make check_mplace public)
- rust-lang#104364 (rustdoc: Resolve doc links in external traits having local impls)
- rust-lang#104378 (Bump chalk to v0.87)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
@bors
bors merged commit 8c77da8 into rust-lang:masterNov 15, 2022
@rustbotrustbot added this to the 1.67.0 milestone Nov 15, 2022
@apirainoapiraino removed the to-announce Announce this issue on triage meeting label Jan 5, 2023
@dtolnaydtolnay mentioned this pull request Sep 28, 2023
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Oct 28, 2023
@bors
Auto merge ofrust-lang#116240- dtolnay:constdiscriminant, r=thomcc
06f9d37
Const stabilize mem::discriminant
Tracking issue: rust-lang#69821.
This PR is a rebase of rust-lang#103893 to resolve conflicts in library/core/src/lib.rs (against rust-lang#102470 and rust-lang#110393).
bors added a commit to rust-lang-ci/rust that referenced this pull request Oct 28, 2023
@bors
Auto merge ofrust-lang#116240- dtolnay:constdiscriminant, r=thomcc
7cc36de
Const stabilize mem::discriminant
Tracking issue: rust-lang#69821.
This PR is a rebase of rust-lang#103893 to resolve conflicts in library/core/src/lib.rs (against rust-lang#102470 and rust-lang#110393).
@dtolnaydtolnay mentioned this pull request Jun 25, 2024
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Jul 13, 2024
@bors
Auto merge ofrust-lang#126958- dtolnay:u32char, r=Mark-Simulacrum
fcaa6fd
Stabilize const unchecked conversion from u32 to char
Closesrust-lang#89259.
The functions in this PR were left out of the initial set of `feature(const_char_convert)` stabilizations in rust-lang#102470, but have since been unblocked by rust-lang#118979.
If `unsafe { from_u32_unchecked(u) }` is called in const with a value for which `from_u32(u)` returns None, we get the following compile error.
```rust
fn main() {
let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
}
```
```console
error[E0080]: it is undefined behavior to use this value
--> src/main.rs:2:19
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered 0x0000d800, but expected a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
= note: the raw bytes of the constant (size: 4, align: 4) {
00 d8 00 00 │ ....
}
note: erroneous constant encountered
--> src/main.rs:2:13
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
github-actionsBot pushed a commit to rust-lang/miri that referenced this pull request Jul 16, 2024
@bors
Auto merge of #126958 - dtolnay:u32char, r=Mark-Simulacrum
c1caca2
Stabilize const unchecked conversion from u32 to char
Closesrust-lang/rust#89259.
The functions in this PR were left out of the initial set of `feature(const_char_convert)` stabilizations in rust-lang/rust#102470, but have since been unblocked by rust-lang/rust#118979.
If `unsafe { from_u32_unchecked(u) }` is called in const with a value for which `from_u32(u)` returns None, we get the following compile error.
```rust
fn main() {
let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
}
```
```console
error[E0080]: it is undefined behavior to use this value
--> src/main.rs:2:19
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered 0x0000d800, but expected a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
= note: the raw bytes of the constant (size: 4, align: 4) {
00 d8 00 00 │ ....
}
note: erroneous constant encountered
--> src/main.rs:2:13
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
lnicola pushed a commit to lnicola/rust-analyzer that referenced this pull request Jul 16, 2024
@bors
Auto merge of #126958 - dtolnay:u32char, r=Mark-Simulacrum
16684c7
Stabilize const unchecked conversion from u32 to char
Closesrust-lang/rust#89259.
The functions in this PR were left out of the initial set of `feature(const_char_convert)` stabilizations in rust-lang/rust#102470, but have since been unblocked by rust-lang/rust#118979.
If `unsafe { from_u32_unchecked(u) }` is called in const with a value for which `from_u32(u)` returns None, we get the following compile error.
```rust
fn main() {
let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
}
```
```console
error[E0080]: it is undefined behavior to use this value
--> src/main.rs:2:19
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered 0x0000d800, but expected a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
= note: the raw bytes of the constant (size: 4, align: 4) {
00 d8 00 00 │ ....
}
note: erroneous constant encountered
--> src/main.rs:2:13
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
Kobzol pushed a commit to Kobzol/portable-simd that referenced this pull request Feb 3, 2026
@bors
Auto merge of #126958 - dtolnay:u32char, r=Mark-Simulacrum
7826d3b
Stabilize const unchecked conversion from u32 to char
Closesrust-lang/rust#89259.
The functions in this PR were left out of the initial set of `feature(const_char_convert)` stabilizations in rust-lang/rust#102470, but have since been unblocked by rust-lang/rust#118979.
If `unsafe { from_u32_unchecked(u) }` is called in const with a value for which `from_u32(u)` returns None, we get the following compile error.
```rust
fn main() {
let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
}
```
```console
error[E0080]: it is undefined behavior to use this value
--> src/main.rs:2:19
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered 0x0000d800, but expected a valid unicode scalar value (in `0..=0x10FFFF` but not in `0xD800..=0xDFFF`)
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
= note: the raw bytes of the constant (size: 4, align: 4) {
00 d8 00 00 │ ....
}
note: erroneous constant encountered
--> src/main.rs:2:13
|
2 | let _ = const { unsafe { char::from_u32_unchecked(0xd800) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
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