numfmt: treat multibyte chars as a single character (#11992)

* treat multibyte chars as a single character

* add test for issue 11937

src/uu/numfmt/src/format.rs

@@ -620,7 +620,7 @@ fn transform_to(
 /// Right-aligns when `right_align` is true, left-aligns otherwise.
 /// Unlike `format!("{:>width$}")`, this handles widths larger than 65535.
 fn pad_string(s: &str, width: usize, fill: char, right_align: bool) -> String {
-    let len = s.len();
+    let len = s.chars().count();
     if len >= width {
         return s.to_string();
     }

tests/by-util/test_numfmt.rs

@@ -1549,3 +1549,13 @@ fn test_si_format_precision_no_cap() {
         .succeeds()
         .stdout_is("1.23457M\n");
 }
+
+// https://github.com/uutils/coreutils/issues/11937
+// numfmt: --format width accounting diverges from GNU for multi-byte --suffix
+#[test]
+fn test_multibyte_suffix_issue11937() {
+    new_ucmd!()
+        .args(&["--suffix=€", "--format=%10.2f", "692"])
+        .succeeds()
+        .stdout_is("   692.00€\n");
+}