Default-able arguments are "missing" when encountering unknown flag with ignore_errors

[MarijnS95]

When parsing unknown flags into a struct that has ignore_errors(true), clap fails with "The following required argument was not provided: bar" upon encountering an unrecognized flag, whereas bar is a bool flag that should default to false.

Repro

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=c8526876b56fbc51bb2a8e2440be52c1

use clap::{CommandFactory, FromArgMatches, Parser};

#[derive(Debug, Parser)]
struct Args {
    #[clap(short, long)]
    bar: bool,
}

fn main() {
    let command = Args::command().ignore_errors(true).no_binary_name(true);

    let args = Args::from_arg_matches(&command.clone().get_matches_from::<_, &str>([])).unwrap();
    assert!(!args.bar);
    dbg!(args);

    let args = Args::from_arg_matches(&command.clone().get_matches_from(["--bar"])).unwrap();
    assert!(args.bar);
    dbg!(args);

    let args = Args::from_arg_matches(&command.clone().get_matches_from(["--foo"])).unwrap();
    assert!(!args.bar);
    dbg!(args);

    let args = Args::from_arg_matches(&command.get_matches_from(["--foo", "--bar"])).unwrap();
    assert!(args.bar);
    dbg!(args);
}

Bonus

I added an example with an unknown arg first, assuming it should step over the unknown arg and still set bar to true based on --bar presence. Not sure if that's possible at all, given that we just discussed positional args vs --bar possibly being a value to the --foo flag...

Originally posted by @MarijnS95 in #1404 (comment)

[MarijnS95]

Originally posted by @MarijnS95 in #1404 (comment)

Looks like this ends up being a duplicate of #4391, after GH title search (when creating issues) is more helpful than a search for keywords on its own.

EDIT: Or not, since it seems to work correctly for me when not passing --bar, and specifically requires an ignored unknown arg first...

[bonigarcia]

I am experiencing this problem as well. The following snippet is the relevant part of my clap setup:

#[derive(Parser, Debug)]
#[clap(version, about, long_about = None, ignore_errors = true, help_template = "\
{name} {version}
{about-with-newline}
{usage-heading} {usage}
{all-args}")]
struct Cli {
    /// Browser name (chrome, firefox, edge, iexplorer, safari, safaritp, or webview2)
    #[clap(long, value_parser)]
    browser: Option<String>,

    // ... More fields

    /// Output type: LOGGER (using INFO, WARN, etc.), JSON (custom JSON notation), or SHELL (Unix-like)
    #[clap(long, value_parser, default_value = "LOGGER")]
    output: String,
	
    // ... More fields
}

When I add ignore_errors = true, after adding a non-supported argument, my CLI tool fails as follows:

error: The following required argument was not provided: output

Is there any plan to fix it? Thank you.