sort: make compare_by honour settings.reverse

This allows sort --merge --reverse to work as well.

src/sort/sort.rs

@@ -265,10 +265,6 @@ fn exec(files: Vec<String>, settings: &Settings) -> i32 {
         lines.dedup()
     }
 
-    if settings.reverse {
-        lines.reverse()
-    }
-
     if settings.check {
         for (i, line) in lines.iter().enumerate() {
             if line != &original_lines[i] {
@@ -298,7 +294,12 @@ fn compare_by(a: &String, b: &String, settings: &Settings) -> Ordering {
     for compare_fn in &settings.compare_fns {
         let cmp = compare_fn(a, b);
         if cmp != Ordering::Equal {
-            return cmp;
+            if settings.reverse {
+                return cmp.reverse();
+            }
+            else {
+                return cmp;
+            }
         }
     }
     return Ordering::Equal;

tests/fixtures/sort/merge_ints_reversed.expected

@@ -0,0 +1,9 @@
+9
+8
+7
+6
+5
+4
+3
+2
+1

tests/fixtures/sort/merge_ints_reversed_1.txt

@@ -0,0 +1,3 @@
+7
+4
+1

tests/fixtures/sort/merge_ints_reversed_2.txt

@@ -0,0 +1,3 @@
+8
+5
+2

tests/fixtures/sort/merge_ints_reversed_3.txt

@@ -0,0 +1,3 @@
+9
+6
+3

tests/test_sort.rs

@@ -80,6 +80,17 @@ fn test_merge_interleaved() {
         .succeeds().stdout_is_fixture("merge_ints_interleaved.expected");
 }
 
+#[test]
+fn test_merge_reversed() {
+    new_ucmd()
+        .arg("-m")
+        .arg("--reverse")
+        .arg("merge_ints_reversed_1.txt")
+        .arg("merge_ints_reversed_2.txt")
+        .arg("merge_ints_reversed_3.txt")
+        .succeeds().stdout_is_fixture("merge_ints_reversed.expected");
+}
+
 #[test]
 fn test_check() {
     new_ucmd()