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| author | bors <bors@rust-lang.org> | 2024-07-13 18:41:08 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2024-07-13 18:41:08 +0000 |
| commit | fcaa6fdfbee1316184e7ad98c53241d52cd30a5f (patch) | |
| tree | 94743d66099962223ba80716da4273c346ca2d68 | |
| parent | 366e558c3be8936bdbf3f733cb5eb48a4feb2ae4 (diff) | |
| parent | 9d3c79bcd01d444a1e075e15a71e31d4ef6ab0d8 (diff) | |
| download | rust-fcaa6fdfbee1316184e7ad98c53241d52cd30a5f.tar.gz rust-fcaa6fdfbee1316184e7ad98c53241d52cd30a5f.zip | |
Auto merge of #126958 - dtolnay:u32char, r=Mark-Simulacrum
Stabilize const unchecked conversion from u32 to char
Closes https://github.com/rust-lang/rust/issues/89259.
The functions in this PR were left out of the initial set of `feature(const_char_convert)` stabilizations in https://github.com/rust-lang/rust/pull/102470, but have since been unblocked by https://github.com/rust-lang/rust/pull/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) } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
| -rw-r--r-- | library/core/src/char/methods.rs | 5 | ||||
| -rw-r--r-- | library/core/src/char/mod.rs | 2 | ||||
| -rw-r--r-- | library/core/src/lib.rs | 1 |
3 files changed, 5 insertions, 3 deletions
diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs index 458be49fb15..4186565c131 100644 --- a/library/core/src/char/methods.rs +++ b/library/core/src/char/methods.rs @@ -223,7 +223,10 @@ impl char { /// assert_eq!('❤', c); /// ``` #[stable(feature = "assoc_char_funcs", since = "1.52.0")] - #[rustc_const_unstable(feature = "const_char_from_u32_unchecked", issue = "89259")] + #[rustc_const_stable( + feature = "const_char_from_u32_unchecked", + since = "CURRENT_RUSTC_VERSION" + )] #[must_use] #[inline] pub const unsafe fn from_u32_unchecked(i: u32) -> char { diff --git a/library/core/src/char/mod.rs b/library/core/src/char/mod.rs index f3683fe3f9c..26b463e25ea 100644 --- a/library/core/src/char/mod.rs +++ b/library/core/src/char/mod.rs @@ -123,7 +123,7 @@ pub const fn from_u32(i: u32) -> Option<char> { /// Converts a `u32` to a `char`, ignoring validity. Use [`char::from_u32_unchecked`]. /// instead. #[stable(feature = "char_from_unchecked", since = "1.5.0")] -#[rustc_const_unstable(feature = "const_char_from_u32_unchecked", issue = "89259")] +#[rustc_const_stable(feature = "const_char_from_u32_unchecked", since = "CURRENT_RUSTC_VERSION")] #[must_use] #[inline] pub const unsafe fn from_u32_unchecked(i: u32) -> char { diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs index 0f82f01e57a..49f89e70255 100644 --- a/library/core/src/lib.rs +++ b/library/core/src/lib.rs @@ -119,7 +119,6 @@ #![feature(const_bigint_helper_methods)] #![feature(const_black_box)] #![feature(const_cell_into_inner)] -#![feature(const_char_from_u32_unchecked)] #![feature(const_eval_select)] #![feature(const_exact_div)] #![feature(const_float_bits_conv)] |