fix: validate if thousands_separator is not multi byte

Author: Kaua-Klassmann

src/uu/sort/src/numeric_str_cmp.rs

@@ -28,7 +28,7 @@ pub struct NumInfo {
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub struct NumInfoParseSettings {
     pub accept_si_units: bool,
-    pub thousands_separator: Option<char>,
+    pub thousands_separator: Option<u8>,
     pub decimal_pt: Option<u8>,
 }
 
@@ -74,7 +74,7 @@ impl NumInfo {
 
             if matches!(
                 parse_settings.thousands_separator,
-                Some(c) if c == char as char
+                Some(c) if c == char
             ) {
                 continue;
             }
@@ -306,7 +306,7 @@ mod tests {
             NumInfo::parse(
                 n,
                 &NumInfoParseSettings {
-                    thousands_separator: Some(','),
+                    thousands_separator: Some(b','),
                     ..Default::default()
                 }
             ),

src/uu/sort/src/sort.rs

@@ -1087,9 +1087,14 @@ impl FieldSelector {
         let mut range_str = &line[self.get_range(line, tokens)];
         if self.settings.mode == SortMode::Numeric || self.settings.mode == SortMode::HumanNumeric {
             // Get the thousands separator from the locale, handling cases where the separator is empty or multi-character
-            let thousands_separator = i18n::decimal::locale_grouping_separator()
-                .parse::<char>()
-                .ok();
+            let locale_thousands_separator = i18n::decimal::locale_grouping_separator().as_bytes();
+
+            // Upstream GNU coreutils ignore multibyte thousands separators
+            // (FIXME in C source). We keep the same single-byte behavior.
+            let thousands_separator = match locale_thousands_separator {
+                [b] => Some(*b),
+                _ => None,
+            };
 
             // Parse NumInfo for this number.
             let (info, num_range) = NumInfo::parse(