Example code of README.md using builder pattern results in panic

[asteding]

Make sure you completed the following tasks

• Searched the discussions
• Searched the closes issues

Code

// (Full example with detailed comments in examples/01a_quick_example.rs)
//
// This example demonstrates clap's "builder pattern" method of creating arguments
// which the most flexible, but also most verbose.
use clap::{Arg, App};

fn main() {
    let matches = App::new("My Super Program")
        .version("1.0")
        .author("Kevin K. <kbknapp@gmail.com>")
        .about("Does awesome things")
        .arg(Arg::new("config")
            .short('c')
            .long("config")
            .value_name("FILE")
            .about("Sets a custom config file")
            .takes_value(true))
        .arg(Arg::new("INPUT")
            .about("Sets the input file to use")
            .required(true)
            .index(1))
        .arg(Arg::new("v")
            .short('v')
            .multiple(true)
            .about("Sets the level of verbosity"))
        .subcommand(App::new("test")
            .about("controls testing features")
            .version("1.3")
            .author("Someone E. <someone_else@other.com>")
            .arg(Arg::new("debug")
                .short('d')
                .about("print debug information verbosely")))
        .get_matches();

    // Same as above examples...
}

Steps to reproduce the issue

1. Run cargo run

Version

• Rust: rustc 1.45.0-nightly (47c3158c3 2020-06-04)
• Clap: 3.0.0-beta.1

Actual Behavior Summary

If i use the above example code from the clap-rs README.md i get a
thread 'main' panicked at 'Argument names must be unique, but '' is in use by more than one argument or group'

Expected Behavior Summary

I think this should happen instead.
error: The following required arguments were not provided:

USAGE:
clap_bug [FLAGS] [OPTIONS] [SUBCOMMAND]

Additional context

Debug output

Compile clap with debug feature:

[dependencies]
clap = { version = "*", features = ["debug"] }

The output may be very long, so feel free to link to a gist or attach a text file

Debug Output

Paste Debug Output Here

[            clap::build::app]  App::_do_parse

[            clap::build::app]  App::_build

[            clap::build::app]  App::_derive_display_order:My Super Program

[            clap::build::app]  App::_derive_display_order:test

[            clap::build::app]  App::_create_help_and_version

[            clap::build::app]  App::_create_help_and_version: Building --help

[            clap::build::app]  App::_create_help_and_version: Building --version

[            clap::build::app]  App::_create_help_and_version: Building help

[            clap::build::app]  App::_debug_asserts

[            clap::build::arg]  Arg::_debug_asserts:

thread 'main' panicked at 'Argument names must be unique, but '' is in use by more than one argument or group', /home/andi/.cargo/registry/src/github.com-1ecc6299db9ec823/clap-3.0.0-beta.1/src/build/app/mod.rs:1613:13

note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

[asteding]

After some research it looks like the field arg.name is always ""

So

assert!(
    two_args_of(|x| x.name == arg.name).is_none(),
    "Argument names must be unique, but '{}' is in use by more than one argument or group",
    arg.name,
    );

returns always a false.

Due to my still little knowledge of Rust i'd be happy to help and learn.
Would someone provide some information where i should look? Probably I need to investigate

impl<'help> Arg<'help> {
    /// @TODO @p2 @docs @v3-beta1: Write Docs
    pub fn new<T: Key + ToString>(t: T) -> Self {
        Arg {
            id: t.into(),
            disp_ord: 999,
            unified_ord: 999,
            ..Default::default()
        }
    }
}

which is lacking a name field too.

[CreepySkeleton]

In the first snippet, the condition must be x.id == arg.id.

Where did you get the second snippet from? I can't find it in the codebase.

[pksunkara]

I don't get it. Our tests should be failing if the condition is wrong.

…

On Mon, Jun 8, 2020, 13:55 CreepySkeleton ***@***.***> wrote: In the first snippet, the condition must be x.id == arg.id. Where did you get the second snippet from? I can't find it in the codebase. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1965 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABKU356EBAPR4DDAIDJSZ3RVTGSDANCNFSM4NX7WYWA> .

[asteding]

Hello @CreepySkeleton ,
it's from here
It also looks like it's already fixed on the master branch?

[CreepySkeleton]

Ah, yes. There used to be Arg::new method different from with_name. We eventually decided to ditch the old new and just rename with_name to new. it happened after the beta release.

This is fixed in master. The condition must be fixed though - it's not wrong, but it would be "more correct" to check id. We would appreciate such PR!

[asteding]

Alright.
Thanks for the feedback.
I'll set up a PR if nobody minds? :-)