Using number_of_values and default_value together

[Frederick888]

Found this issue with clap 2.26.2

It seems that currently the default value is implemented by appending it to the existing matches. But it causes issues if a combination of number_of_values and default_value is used.

For instance,

extern crate clap;

use clap::{App, Arg};

fn main() {
    let m = App::new("hello_world")
        .arg(
            Arg::with_name("exit-code")
                .long("exit-code")
                .required(true)
                .takes_value(true)
                .number_of_values(1)
                .default_value("0"),
        )
        .get_matches();
    println!(
        "{:?}",
        m.values_of("exit-code").unwrap().collect::<Vec<_>>()
    );
}

⇒  ./hello_world --exit-code
["0"]
⇒  ./hello_world --exit-code 1
error: The argument '--exit-code <exit-code>' requires 1 values, but 2 were provided

USAGE:
    hello_world --exit-code <exit-code>

For more information try --help

Changing number_of_values(1) to number_of_values(2) would make it work if the argument is correctly given but the error message is still off when it's not provided:

⇒  ./hello_world --exit-code  
error: The argument '--exit-code <exit-code> <exit-code>' requires 2 values, but 1 was provided

USAGE:
    hello_world --exit-code <exit-code> <exit-code>

For more information try --help

[Frederick888]

diff --git a/src/app/parser.rs b/src/app/parser.rs
index 6ec72034..35eb3f9b 100644
--- a/src/app/parser.rs
+++ b/src/app/parser.rs
@@ -1733,15 +1733,8 @@ impl<'a, 'b> Parser<'a, 'b>
                 if let Some(ref val) = $a.v.default_val {
                     if $m.get($a.b.name).map(|ma| ma.vals.len()).map(|len| len == 0).unwrap_or(false) {
                         $_self.add_val_to_arg($a, OsStr::new(val), $m)?;
 
-                        if $_self.cache.map_or(true, |name| name != $a.name()) {
-                            arg_post_processing!($_self, $a, $m);
-                            $_self.cache = Some($a.name());
-                        }
-                    } else {
-                        $_self.add_val_to_arg($a, OsStr::new(val), $m)?;
-
                         if $_self.cache.map_or(true, |name| name != $a.name()) {
                             arg_post_processing!($_self, $a, $m);
                             $_self.cache = Some($a.name());
                         }

...fixes it for me. But I'm not really clear about the purpose of the codes here.

[kbknapp]

Yep, I just saw this when going through #1056

I'm not sure why it's doing the same thing in both branches 😕