Sort debug message

src/uu/sort/locales/en-US.ftl

@@ -63,6 +63,7 @@ sort-failed-to-set-up-signal-handler = failed to set up signal handler: {$error}
 # Warning messages
 sort-warning-failed-to-set-locale = failed to set locale
 sort-warning-simple-byte-comparison = text ordering performed using simple byte comparison
+sort-warning-sort-rule = text ordering performed using ‘{$locale}’ sorting rules
 sort-warning-key-zero-width = key {$key} has zero width and will be ignored
 sort-warning-key-numeric-spans-fields = key {$key} is numeric and spans multiple fields
 sort-warning-leading-blanks-significant = leading blanks are significant in key {$key}; consider also specifying 'b'

src/uu/sort/src/sort.rs

@@ -1797,7 +1797,17 @@ fn emit_debug_warnings(
         show_error!("{}", translate!("sort-warning-failed-to-set-locale"));
     }
 
-    show_error!("{}", translate!("sort-warning-simple-byte-comparison"));
+    let (locale, encoding) = i18n::get_collating_locale();
+
+    if matches!(encoding, i18n::UEncoding::Utf8) {
+        let locale_as_posix = format!("{}.UTF-8", locale.to_string().replace('-', "_"));
+        show_error!(
+            "{}",
+            translate!("sort-warning-sort-rule", "locale" => locale_as_posix)
+        );
+    } else {
+        show_error!("{}", translate!("sort-warning-simple-byte-comparison"));
+    }
 
     for (idx, selector) in settings.selectors.iter().enumerate() {
         let key_index = idx + 1;

src/uucore/src/lib/features/i18n/mod.rs

@@ -75,7 +75,7 @@ pub fn get_locale_from_env(locale_name: &str) -> (Locale, UEncoding) {
 }
 
 /// Get the collating locale from the environment
-fn get_collating_locale() -> &'static (Locale, UEncoding) {
+pub fn get_collating_locale() -> &'static (Locale, UEncoding) {
     static COLLATING_LOCALE: OnceLock<(Locale, UEncoding)> = OnceLock::new();
 
     COLLATING_LOCALE.get_or_init(|| get_locale_from_env("LC_COLLATE"))

tests/by-util/test_sort.rs

@@ -2713,6 +2713,26 @@ fn test_locale_complex_utf8_sorting() {
         .stdout_is("apple\nApple\nbanana\nBanana\nzebra\nZebra\n");
 }
 
+#[test]
+fn test_locale_posix_sort_debug_message() {
+    new_ucmd!()
+        .env("LC_ALL", "C")
+        .arg("--debug")
+        .pipe_in("a\nA\nb\nB\n")
+        .succeeds()
+        .stderr_contains("text ordering performed using simple byte comparison");
+}
+
+#[test]
+fn test_locale_utf8_sort_debug_message() {
+    new_ucmd!()
+        .env("LC_ALL", "en_US.UTF-8")
+        .arg("--debug")
+        .pipe_in("a\nA\nb\nB\n")
+        .succeeds()
+        .stderr_contains("text ordering performed using ‘en_US.UTF-8’ sorting rules");
+}
+
 #[test]
 fn test_locale_utf8_with_key_field() {
     // Regression test for issue #10909