displaying help for subcommands should disable top level argument requirements

[Geal]

Rust Version

rustc 1.15.0-nightly (2217bd771 2016-11-25)

Affected Version of clap

2.19.2

Expected Behavior Summary

With an executable taking a top level required argument "foo", and a subcommand "bar", displaying bar's help with ./clap-test bar --help should display the help like this:

$ ./target/debug/clap-test bar --help
clap-test-bar
bar

USAGE:
    clap-test bar --baz <baz>

FLAGS:
    -h, --help       Prints help information
    -V, --version    Prints version information

OPTIONS:
        --baz <baz>    baz

Actual Behavior Summary

$ ./target/debug/clap-test bar --help 
error: The following required arguments were not provided:
    --foo <FILE>

USAGE:
    clap-test --foo <FILE> [SUBCOMMAND]

For more information try --help

Steps to Reproduce the issue

Build and run the attached code

Sample Code or Link to Sample Code

#[macro_use] extern crate clap;
use clap::{App,Arg,SubCommand};

fn main() {
  let matches = App::new("test")
                        .version(crate_version!())
                        .arg(Arg::with_name("foo")
                                    .long("foo")
                                    .value_name("FILE")
                                    .help("Sets a custom config file")
                                    .takes_value(true)
                                    .required(true))
                        .subcommand(SubCommand::with_name("bar")
                                    .about("bar")
                                    .arg(Arg::with_name("baz").long("baz")
                                         .takes_value(true).required(true).help("baz")))
                        .get_matches();
}

Debug output

$ ./target/debug/clap-test bar --help
*DEBUG:clap: fn=Parser::add_subcommand;
*DEBUG:clap: Term width...None
*DEBUG:clap: Is help...No
*DEBUG:clap: VersionlessSubcommands set...false
*DEBUG:clap: GlobalVersion set...false
*DEBUG:clap: fn=get_matches_with;
*DEBUG:clap: fn=create_help_and_version;
*DEBUG:clap: Building --help
*DEBUG:clap: Building --version
*DEBUG:clap: Building help
*DEBUG:clap: Begin parsing '"bar"' ([98, 97, 114])
*DEBUG:clap: fn=check_is_new_arg;nvo=None
*DEBUG:clap: Does arg allow leading hyphen...false
*DEBUG:clap: Starts new arg...Probable value
*DEBUG:clap: Starts new arg...false
*DEBUG:clap: fn=possible_subcommand
*DEBUG:clap: fn=validate_blacklist;blacklist=[]
*DEBUG:clap: fn=validate_num_args;
*DEBUG:clap: fn=create_usage;
*DEBUG:clap: fn=create_usage_no_title;
*DEBUG:clap: args_in_groups=[]
*DEBUG:clap: fn=fmt
*DEBUG:clap: fn=needs_flags_tag;
*DEBUG:clap: iter;f=hclap_help;
*DEBUG:clap: iter;f=vclap_version;
*DEBUG:clap: fn=validate_required;required=["foo"];
*DEBUG:clap: iter;name=foo
*DEBUG:clap: fn=is_missing_required_ok;a=foo
*DEBUG:clap: args_in_groups=[]
*DEBUG:clap: fn=fmt
*DEBUG:clap: fn=create_usage;
*DEBUG:clap: fn=create_usage_no_title;
*DEBUG:clap: args_in_groups=[]
*DEBUG:clap: fn=fmt
*DEBUG:clap: fn=needs_flags_tag;
*DEBUG:clap: iter;f=hclap_help;
*DEBUG:clap: iter;f=vclap_version;
*DEBUG:clap: fn=color;
*DEBUG:clap: Color setting...Auto
*DEBUG:clap: fn=error;
*DEBUG:clap: fn=is_a_tty;
*DEBUG:clap: Use stderr...true
*DEBUG:clap: fn=good;
*DEBUG:clap: fn=is_a_tty;
*DEBUG:clap: Use stderr...true
error: The following required arguments were not provided:
    --foo <FILE>

USAGE:
    clap-test --foo <FILE> [SUBCOMMAND]

For more information try --help

[Geal]

Trying different versions of calling help:

prog bar --help -> doesn't work
prog bar -h -> doesn't work
prog bar help -> doesn't work
prog help bar -> works

[kbknapp]

Thanks for letting me know about this! It's fixed, I'll push 2.19.3 to crates.io 😉