ls: ignore leading period when sorting by name (#2112)

* ls: ignore leading period when sorting by name

ls now behaves like GNU ls with respect to sorting files by ignoring
leading periods when sorting by main.

Added tests to ensure "touch a .a b .b ; ls" returns ".a  a  .b  b"

* Replaced clone/collect calls.

src/uu/ls/src/ls.rs

@@ -1139,7 +1139,13 @@ fn sort_entries(entries: &mut Vec<PathData>, config: &Config) {
             entries.sort_by_key(|k| Reverse(k.md().as_ref().map(|md| md.len()).unwrap_or(0)))
         }
         // The default sort in GNU ls is case insensitive
-        Sort::Name => entries.sort_by_cached_key(|k| k.file_name.to_lowercase()),
+        Sort::Name => entries.sort_by_cached_key(|k| {
+            let has_dot: bool = k.file_name.starts_with('.');
+            let filename_nodot: &str = &k.file_name[if has_dot { 1 } else { 0 }..];
+            // We want hidden files to appear before regular files of the same
+            // name, so we need to negate the "has_dot" variable.
+            (filename_nodot.to_lowercase(), !has_dot)
+        }),
         Sort::Version => entries.sort_by(|k, j| version_cmp::version_cmp(&k.p_buf, &j.p_buf)),
         Sort::None => {}
     }

tests/by-util/test_ls.rs

@@ -481,6 +481,21 @@ fn test_ls_sort_name() {
         .arg("--sort=name")
         .succeeds()
         .stdout_is(["test-1", "test-2", "test-3\n"].join(sep));
+
+    // Order of a named sort ignores leading dots.
+    let scene_dot = TestScenario::new(util_name!());
+    let at = &scene_dot.fixtures;
+    at.touch(".a");
+    at.touch("a");
+    at.touch(".b");
+    at.touch("b");
+
+    scene_dot
+        .ucmd()
+        .arg("--sort=name")
+        .arg("-A")
+        .succeeds()
+        .stdout_is([".a", "a", ".b", "b\n"].join(sep));
 }
 
 #[test]