Formatting with width and separator doesn't work correctly (RustPython#5927)

* Fix add_magnitude_separators

* Add extra tests

Author: yt2b

common/src/format.rs

@@ -436,8 +436,12 @@ impl FormatSpec {
                 let sep = char::from(fg);
                 let inter = self.get_separator_interval().try_into().unwrap();
                 let magnitude_len = magnitude_str.len();
-                let width = self.width.unwrap_or(magnitude_len) as i32 - prefix.len() as i32;
-                let disp_digit_cnt = cmp::max(width, magnitude_len as i32);
+                let disp_digit_cnt = if self.fill == Some('0'.into()) {
+                    let width = self.width.unwrap_or(magnitude_len) as i32 - prefix.len() as i32;
+                    cmp::max(width, magnitude_len as i32)
+                } else {
+                    magnitude_len as i32
+                };
                 Self::add_magnitude_separators_for_char(magnitude_str, inter, sep, disp_digit_cnt)
             }
             None => magnitude_str,

extra_tests/snippets/builtin_format.py

@@ -81,6 +81,9 @@ def test_zero_padding():
 assert f"{123.456:+011,}" == "+00,123.456"
 assert f"{1234:.3g}" == "1.23e+03"
 assert f"{1234567:.6G}" == "1.23457E+06"
+assert f"{1234:10}" == "      1234"
+assert f"{1234:10,}" == "     1,234"
+assert f"{1234:010,}" == "00,001,234"
 assert f"{'🐍':4}" == "🐍   "
 assert_raises(
     ValueError, "{:,o}".format, 1, _msg="ValueError: Cannot specify ',' with 'o'."
@@ -165,6 +168,9 @@ def test_zero_padding():
 assert f"{3.1415:#.2}" == "3.1"
 assert f"{3.1415:#.3}" == "3.14"
 assert f"{3.1415:#.4}" == "3.142"
+assert f"{1234.5:10}" == "    1234.5"
+assert f"{1234.5:10,}" == "   1,234.5"
+assert f"{1234.5:010,}" == "0,001,234.5"
 assert f"{12.34 + 5.6j}" == "(12.34+5.6j)"
 assert f"{12.34 - 5.6j: }" == "( 12.34-5.6j)"
 assert f"{12.34 + 5.6j:20}" == "        (12.34+5.6j)"