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Rollup merge of #93392 - GKFX:char-docs, r=scottmcm

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Clarify documentation on char::MAX

As mentioned in https://github.com/rust-lang/rust/issues/91836#issuecomment-994106874, the documentation on `char::MAX` is not quite correct – USVs are not "only ones within a certain range", they are code points _outside_ a certain range. I have corrected this and given the actual numbers as there is no reason to hide them.
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Matthias Krüger 2022-01-31 06:58:32 +01:00 • committed by GitHub
commit c03bf54dd1
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2 changed files with 22 additions and 12 deletions
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17
library/core/src/char/methods.rs
View file

@ -9,14 +9,19 @@ use super::*;
#[lang = "char"]
impl char {
/// The highest valid code point a `char` can have.
/// The highest valid code point a `char` can have, `'\u{10FFFF}'`.
///
/// A `char` is a [Unicode Scalar Value], which means that it is a [Code
/// Point], but only ones within a certain range. `MAX` is the highest valid
/// code point that's a valid [Unicode Scalar Value].
/// # Examples
///
/// [Unicode Scalar Value]: https://www.unicode.org/glossary/#unicode_scalar_value
/// [Code Point]: https://www.unicode.org/glossary/#code_point
/// ```
/// # fn something_which_returns_char() -> char { 'a' }
/// let c: char = something_which_returns_char();
/// assert!(c <= char::MAX);
///
/// let value_at_max = char::MAX as u32;
/// assert_eq!(char::from_u32(value_at_max), Some('\u{10FFFF}'));
/// assert_eq!(char::from_u32(value_at_max + 1), None);
/// ```
#[stable(feature = "assoc_char_consts", since = "1.52.0")]
pub const MAX: char = '\u{10ffff}';

17
library/core/src/char/mod.rs
View file

@ -89,14 +89,19 @@ const MAX_THREE_B: u32 = 0x10000;
Cn Unassigned a reserved unassigned code point or a noncharacter
*/
/// The highest valid code point a `char` can have.
/// The highest valid code point a `char` can have, `'\u{10FFFF}'`.
///
/// A [`char`] is a [Unicode Scalar Value], which means that it is a [Code
/// Point], but only ones within a certain range. `MAX` is the highest valid
/// code point that's a valid [Unicode Scalar Value].
/// # Examples
///
/// [Unicode Scalar Value]: https://www.unicode.org/glossary/#unicode_scalar_value
/// [Code Point]: https://www.unicode.org/glossary/#code_point
/// ```
/// # fn something_which_returns_char() -> char { 'a' }
/// let c: char = something_which_returns_char();
/// assert!(c <= char::MAX);
///
/// let value_at_max = char::MAX as u32;
/// assert_eq!(char::from_u32(value_at_max), Some('\u{10FFFF}'));
/// assert_eq!(char::from_u32(value_at_max + 1), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub const MAX: char = char::MAX;