min_values(0) still complains about no value when combining short versions

[miDeb]

Please complete the following tasks

• I have searched the discussions
• I have searched the existing issues

Rust Version

rustc 1.56.0-nightly (9c25eb7aa 2021-07-25)

Clap Version

2.33

Minimal reproducible code

use clap::{App, Arg};

fn main() {
    let matches = App::new("foo")
        .arg(
            Arg::with_name("check")
                .short("c")
                .long("check")
                .takes_value(true)
                .require_equals(true)
                .min_values(0)
                .possible_values(&["silent", "quiet", "diagnose-first"])
                .help("check for sorted input; do not sort"),
        )
        .arg(
            Arg::with_name("unique")
                .short("u")
                .long("unique")
                .help("output only the first of an equal run"),
        )
        .get_matches();
    assert!(matches.is_present("check"));
    assert!(matches.is_present("unique"));
}

Steps to reproduce the bug with the above code

cargo r -- -cu

Actual Behaviour

error: The argument '--check=<check>' requires a value but none was supplied

USAGE:
    clap-bug [FLAGS] [OPTIONS]

For more information try --help

Expected Behaviour

The same thing that happens when invoking the program like this: cargo r -- -u -c, which should be synomymous to -cu.
The program would succeed and produce no output.

Additional Context

No response

Debug Output

DEBUG:clap:Parser::propagate_settings: self=foo, g_settings=AppFlags(
    (empty),
)
DEBUG:clap:Parser::get_matches_with;
DEBUG:clap:Parser::create_help_and_version;
DEBUG:clap:Parser::create_help_and_version: Building --help
DEBUG:clap:Parser::create_help_and_version: Building --version
DEBUG:clap:Parser::get_matches_with: Begin parsing '"-cu"' ([45, 99, 117])
DEBUG:clap:Parser::is_new_arg:"-cu":NotFound
DEBUG:clap:Parser::is_new_arg: arg_allows_tac=false
DEBUG:clap:Parser::is_new_arg: - found
DEBUG:clap:Parser::is_new_arg: starts_new_arg=true
DEBUG:clap:Parser::possible_subcommand: arg="-cu"
DEBUG:clap:Parser::get_matches_with: possible_sc=false, sc=None
DEBUG:clap:ArgMatcher::process_arg_overrides:None;
DEBUG:clap:Parser::parse_short_arg: full_arg="-cu"
DEBUG:clap:Parser::parse_short_arg:iter:c
DEBUG:clap:Parser::parse_short_arg:iter:c: Found valid opt
DEBUG:clap:Parser::parse_short_arg:iter:c: p[0]=[], p[1]=[117]
DEBUG:clap:Parser::parse_short_arg:iter:c: val=[117] (bytes), val="u" (ascii)
DEBUG:clap:Parser::parse_opt; opt=check, val=Some("u")
DEBUG:clap:Parser::parse_opt; opt.settings=ArgFlags(TAKES_VAL | DELIM_NOT_SET | REQUIRE_EQUALS)
DEBUG:clap:Parser::parse_opt; Checking for val...Found Empty - Error
DEBUG:clap:usage::create_usage_with_title;
DEBUG:clap:usage::create_usage_no_title;
DEBUG:clap:usage::get_required_usage_from: reqs=[], extra=None
DEBUG:clap:usage::get_required_usage_from: after init desc_reqs=[]
DEBUG:clap:usage::get_required_usage_from: no more children
DEBUG:clap:usage::get_required_usage_from: final desc_reqs=[]
DEBUG:clap:usage::get_required_usage_from: args_in_groups=[]
DEBUG:clap:usage::needs_flags_tag;
DEBUG:clap:usage::needs_flags_tag:iter: f=unique;
DEBUG:clap:Parser::groups_for_arg: name=unique
DEBUG:clap:Parser::groups_for_arg: No groups defined
DEBUG:clap:usage::needs_flags_tag:iter: [FLAGS] required
DEBUG:clap:usage::create_help_usage: usage=clap-bug [FLAGS] [OPTIONS]
DEBUG:clap:Parser::color;
DEBUG:clap:Parser::color: Color setting...Auto
DEBUG:clap:is_a_tty: stderr=true
DEBUG:clap:Colorizer::error;
DEBUG:clap:OptBuilder::fmt:check
DEBUG:clap:Colorizer::warning;
DEBUG:clap:Colorizer::good;
error: The argument '--check=<check>' requires a value but none was supplied

USAGE:
    clap-bug [FLAGS] [OPTIONS]

For more information try --help

[epage]

Looks to be an ordering issue. We pull out the value before checking RequireEquals

I feel like this is something that would be made easier to fix once we've refactored to having a dedicated lexer, see #2615

[ldm0]

Current master behaviour:

use clap::{App, Arg};
fn main() {
    let matches = App::new("foo")
        .arg(
            Arg::new("check")
                .short('c')
                .long("check")
                .require_equals(true)
                .min_values(0)
                .possible_values(&["silent", "quiet", "diagnose-first"]),
        )
        .arg(
            Arg::new("unique")
                .short('u')
                .long("unique")
        )
        .get_matches();
    assert!(matches.is_present("check"));
    assert!(matches.is_present("unique"));
}

error: "u" isn't a valid value for '--check=<check>...'
        [possible values: diagnose-first, quiet, silent]

USAGE:
    rust_test2 --check=<check>...

For more information try --help

[miDeb]

This looks like it doesn't take require_equals(true) into account on current master.