sort: fix debug output for zeros / invalid numbers

We were reporting "no match" when sorting something like "0 ". This is
because we don't distinguish between 0 and invalid lines when sorting.
For debug output we have to get this information back.

src/uu/sort/src/numeric_str_cmp.rs

@@ -46,7 +46,12 @@ impl Default for NumInfoParseSettings {
 
 impl NumInfo {
     /// Parse NumInfo for this number.
-    /// Also returns the range of num that should be passed to numeric_str_cmp later
+    /// Also returns the range of num that should be passed to numeric_str_cmp later.
+    ///
+    /// Leading zeros will be excluded from the returned range. If the number consists of only zeros,
+    /// an empty range (idx..idx) is returned so that idx is the char after the last zero.
+    /// If the input is not a number (which has to be treated as zero), the returned empty range
+    /// will be 0..0.
     pub fn parse(num: &str, parse_settings: NumInfoParseSettings) -> (Self, Range<usize>) {
         let mut exponent = -1;
         let mut had_decimal_pt = false;
@@ -105,7 +110,15 @@ impl NumInfo {
                             sign: if had_digit { sign } else { Sign::Positive },
                             exponent: 0,
                         },
-                        0..0,
+                        if had_digit {
+                            // In this case there were only zeroes.
+                            // For debug output to work properly, we have to match the character after the last zero.
+                            idx..idx
+                        } else {
+                            // This was no number at all.
+                            // For debug output to work properly, we have to match 0..0.
+                            0..0
+                        },
                     )
                 };
             }

src/uu/sort/src/sort.rs

@@ -414,6 +414,7 @@ impl<'a> Line<'a> {
                     selection.start += num_range.start;
                     selection.end = selection.start + num_range.len();
 
+                    if num_range != (0..0) {
                         // include a trailing si unit
                         if selector.settings.mode == SortMode::HumanNumeric
                             && self.line[selection.end..initial_selection.end]
@@ -428,6 +429,15 @@ impl<'a> Line<'a> {
                         {
                             selection.start -= 1;
                         }
+                    } else {
+                        // This was not a valid number.
+                        // Report no match at the first non-whitespace character.
+                        let leading_whitespace = self.line[selection.clone()]
+                            .find(|c: char| !c.is_whitespace())
+                            .unwrap_or(0);
+                        selection.start += leading_whitespace;
+                        selection.end += leading_whitespace;
+                    }
                 }
                 SortMode::GeneralNumeric => {
                     let initial_selection = &self.line[selection.clone()];

tests/by-util/test_sort.rs

@@ -123,6 +123,14 @@ fn test_multiple_decimals_numeric() {
     )
 }
 
+#[test]
+fn test_numeric_with_trailing_invalid_chars() {
+    test_helper(
+        "numeric_trailing_chars",
+        &["-n", "--numeric-sort", "--sort=numeric"],
+    )
+}
+
 #[test]
 fn test_check_zero_terminated_failure() {
     new_ucmd!()

tests/fixtures/sort/human_block_sizes.expected

@@ -1,3 +1,4 @@
+K
 844K
 981K
 11M

tests/fixtures/sort/human_block_sizes.expected.debug

@@ -1,3 +1,6 @@
+K
+^ no match for key
+_
 844K
 ____
 ____

tests/fixtures/sort/human_block_sizes.txt

@@ -9,3 +9,4 @@
 844K
 981K
 13M
+K

tests/fixtures/sort/numeric_trailing_chars.expected

@@ -0,0 +1,5 @@
+-.05,
+-x
+0.abc
+0foo
+100 

tests/fixtures/sort/numeric_trailing_chars.expected.debug

@@ -0,0 +1,15 @@
+-.05,
+____
+_____
+-x
+^ no match for key
+__
+0.abc
+__
+_____
+0foo
+_
+____
+100 
+___
+____

tests/fixtures/sort/numeric_trailing_chars.txt

@@ -0,0 +1,5 @@
+0foo
+0.abc
+100 
+-.05,
+-x