`PythonFormat` ignores zero-padding for integer formats like `%04d`

[ilka-schulz]

Description

dynfmt::PythonFormat does not appear to apply zero-padding when formatting integers. For example, formatting an integer with %04d produces 42 instead of 0042.

Reproduction

use dynfmt::{Format, PythonFormat};

fn main() {
    let result = PythonFormat
        .format("%04d", &[42])
        .unwrap();

    assert_eq!(result, "0042");
}

• expected behavior: 0042
• actual behavior: 42

Notes

The parser appears to recognize both the field width and the 0 flag, but these formatting options do not seem to be applied when the value is eventually formatted.

Since %04d is valid Python-style % formatting as well as standard printf-style formatting, I would expect PythonFormat to honor the requested width and zero-padding.

It looks like other formatting options stored in the parsed argument specification, such as width/alignment/precision, may potentially be affected by the same issue.

AI Disclaimer

I found this issue myself when using dynfmt on a project. However, I did let ChatGPT write the content of this issue to save time.