1 files changed, 21 insertions, 4 deletions
diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index eae567cad..b7a63b7c6 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -746,10 +746,19 @@ impl char {
     /// assert!(!'中'.is_lowercase());
     /// assert!(!' '.is_lowercase());
     /// ```
+    ///
+    /// In a const context:
+    ///
+    /// ```
+    /// #![feature(const_unicode_case_lookup)]
+    /// const CAPITAL_DELTA_IS_LOWERCASE: bool = 'Δ'.is_lowercase();
+    /// assert!(!CAPITAL_DELTA_IS_LOWERCASE);
+    /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
     #[inline]
-    pub fn is_lowercase(self) -> bool {
+    pub const fn is_lowercase(self) -> bool {
         match self {
             'a'..='z' => true,
             c => c > '\x7f' && unicode::Lowercase(c),
@@ -779,10 +788,19 @@ impl char {
     /// assert!(!'中'.is_uppercase());
     /// assert!(!' '.is_uppercase());
     /// ```
+    ///
+    /// In a const context:
+    ///
+    /// ```
+    /// #![feature(const_unicode_case_lookup)]
+    /// const CAPITAL_DELTA_IS_UPPERCASE: bool = 'Δ'.is_uppercase();
+    /// assert!(CAPITAL_DELTA_IS_UPPERCASE);
+    /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
     #[inline]
-    pub fn is_uppercase(self) -> bool {
+    pub const fn is_uppercase(self) -> bool {
         match self {
             'A'..='Z' => true,
             c => c > '\x7f' && unicode::Uppercase(c),
@@ -892,8 +910,7 @@ impl char {
     ///
     /// The general categories for numbers (`Nd` for decimal digits, `Nl` for letter-like numeric
     /// characters, and `No` for other numeric characters) are specified in the [Unicode Character
-    /// Database][ucd] [`UnicodeData.txt`]. Note that this means ideographic numbers like '三'
-    /// are considered alphabetic, not numeric. Please consider to use `is_ascii_digit` or `is_digit`.
+    /// Database][ucd] [`UnicodeData.txt`].
     ///
     /// This method doesn't cover everything that could be considered a number, e.g. ideographic numbers like '三'.
     /// If you want everything including characters with overlapping purposes then you might want to use