ls: don't escape backslash in shell style quoting

src/uu/ls/src/quoting_style.rs

@@ -1,6 +1,6 @@
 use std::char::from_digit;
 
-const SPECIAL_SHELL_CHARS: &str = "~`#$&*()\\|[]{};'\"<>?! ";
+const SPECIAL_SHELL_CHARS: &str = "~`#$&*()|[]{};'\"<>?! ";
 
 pub(super) enum QuotingStyle {
     Shell {
@@ -135,7 +135,6 @@ impl EscapedChar {
             '\x0B' => Backslash('v'),
             '\x0C' => Backslash('f'),
             '\r' => Backslash('r'),
-            '\\' => Backslash('\\'),
             '\x00'..='\x1F' | '\x7F' => Octal(EscapeOctal::from(c)),
             '\'' => match quotes {
                 Quotes::Single => Backslash('\''),
@@ -627,4 +626,22 @@ mod tests {
             ],
         );
     }
+
+    #[test]
+    fn test_backslash() {
+        // Escaped in C-style, but not in Shell-style escaping
+        check_names(
+            "one\\two",
+            vec![
+                ("one\\two", "literal"),
+                ("one\\two", "literal-show"),
+                ("one\\\\two", "escape"),
+                ("\"one\\\\two\"", "c"),
+                ("one\\two", "shell"),
+                ("\'one\\two\'", "shell-always"),
+                ("one\\two", "shell-escape"),
+                ("'one\\two'", "shell-escape-always"),
+            ],
+        );
+    }
 }

tests/by-util/test_ls.rs

@@ -1049,6 +1049,7 @@ fn test_ls_quoting_style() {
 
     at.touch("one two");
     at.touch("one");
+    at.touch("one\\two");
 
     // It seems that windows doesn't allow \n in filenames.
     #[cfg(unix)]
@@ -1168,6 +1169,27 @@ fn test_ls_quoting_style() {
             .succeeds()
             .stdout_only(format!("{}\n", correct));
     }
+
+    for (arg, correct) in &[
+        ("--quoting-style=literal", "one\\two"),
+        ("-N", "one\\two"),
+        ("--quoting-style=c", "\"one\\\\two\""),
+        ("-Q", "\"one\\\\two\""),
+        ("--quote-name", "\"one\\\\two\""),
+        ("--quoting-style=escape", "one\\\\two"),
+        ("-b", "one\\\\two"),
+        ("--quoting-style=shell-escape", "one\\two"),
+        ("--quoting-style=shell-escape-always", "'one\\two'"),
+        ("--quoting-style=shell", "one\\two"),
+        ("--quoting-style=shell-always", "'one\\two'"),
+    ] {
+        scene
+            .ucmd()
+            .arg(arg)
+            .arg("one\\two")
+            .succeeds()
+            .stdout_only(format!("{}\n", correct));
+    }
 }
 
 #[test]