Clap: YAML not parsed when name, version, author, about not specified in it

[Hellseher]

Rust Version

rustc 1.28.0 (9634041f0 2018-07-30)

Affected Version of clap

[dependencies.clap]
version = "2.31.2"
features = [ "yaml"]

Bug or Feature Request Summary

Expected Behavior Summary

By using method and macros build arguments from yml file where that filed not specified.

    .about(crate_description!())
    .name(crate_name!())
    .author(crate_authors!())
    .version(crate_version!())

Actual Behavior Summary

Arguments list is ignored completely

Steps to Reproduce the issue

Sample Code or Link to Sample Code

__cli.yml__
```name:
version:
author:
about:
args:

• harware:
  short: H
  long: hardware
  help: Show system hardware specification
• config:
  short: c
  long: config
  value_name: FILE
  help: Sets a custom config file
  takes_value: true
• INPUT:
  help: Sets the input file to use
  required: true
  index: 1
• verbose:
  short: v
  multiple: true
  help: Sets the level of verbosity

__main.rs__

```#[macro_use]
extern crate clap;

use clap::App;

fn main() {
    let cli_yaml = load_yaml!("cli.yml");
    let matches = App::from_yaml(cli_yaml)
        .about(crate_description!())
        .name(crate_name!())
        .author(crate_authors!())
        .version(crate_version!())
        .get_matches();

    let config = matches.value_of("config").unwrap_or("default.conf");
    println!("Value for config: {}", config);
}
// End of main.rs

### Debug output

Debug Output

DEBUG:clap:Parser::propagate_settings: self=stem, 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 '"--help"' ([45, 45, 104, 101, 108, 112])
DEBUG:clap:Parser::is_new_arg:"--help":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="--help"
DEBUG:clap:Parser::get_matches_with: possible_sc=false, sc=None
DEBUG:clap:ArgMatcher::process_arg_overrides:None;
DEBUG:clap:Parser::parse_long_arg;
DEBUG:clap:Parser::parse_long_arg: Does it contain '='...No
DEBUG:clap:Parser::parse_long_arg: Found valid flag '--help'
DEBUG:clap:Parser::check_for_help_and_version_str;
DEBUG:clap:Parser::check_for_help_and_version_str: Checking if --help is help or version...Help
DEBUG:clap:Parser::_help: use_long=true
DEBUG:clap:Help::write_parser_help;
DEBUG:clap:Help::write_parser_help;
DEBUG:clap:Parser::color;
DEBUG:clap:Parser::color: Color setting...Auto
DEBUG:clap:is_a_tty: stderr=false
DEBUG:clap:Help::new;
DEBUG:clap:Help::write_help;
DEBUG:clap:Help::write_default_help;
DEBUG:clap:Help::write_bin_name;
DEBUG:clap:Help::write_version;
DEBUG:clap:Help::write_default_help: writing about
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=hclap_help;
DEBUG:clap:usage::needs_flags_tag:iter: f=vclap_version;
DEBUG:clap:usage::needs_flags_tag: [FLAGS] not required
DEBUG:clap:usage::create_help_usage: usage=stem
DEBUG:clap:Help::write_all_args;
DEBUG:clap:Help::write_args;
DEBUG:clap:Help::write_args: Current Longest...2
DEBUG:clap:Help::write_args: New Longest...6
DEBUG:clap:Help::write_args: Current Longest...6
DEBUG:clap:Help::write_args: New Longest...9
DEBUG:clap:Help::write_arg;
DEBUG:clap:Help::short;
DEBUG:clap:Help::long;
DEBUG:clap:Help::val: arg=--help
DEBUG:clap:Help::spec_vals: a=--help
DEBUG:clap:Help::val: Has switch...Yes
DEBUG:clap:Help::val: force_next_line...false
DEBUG:clap:Help::val: nlh...false
DEBUG:clap:Help::val: taken...21
DEBUG:clap:Help::val: help_width > (width - taken)...23 > (120 - 21)
DEBUG:clap:Help::val: longest...9
DEBUG:clap:Help::val: next_line...No
DEBUG:clap:write_spaces!: num=7
DEBUG:clap:Help::help;
DEBUG:clap:Help::help: Next Line...false
DEBUG:clap:Help::help: Too long...No
DEBUG:clap:Help::write_arg;
DEBUG:clap:Help::short;
DEBUG:clap:Help::long;
DEBUG:clap:Help::val: arg=--version
DEBUG:clap:Help::spec_vals: a=--version
DEBUG:clap:Help::val: Has switch...Yes
DEBUG:clap:Help::val: force_next_line...false
DEBUG:clap:Help::val: nlh...false
DEBUG:clap:Help::val: taken...21
DEBUG:clap:Help::val: help_width > (width - taken)...26 > (120 - 21)
DEBUG:clap:Help::val: longest...9
DEBUG:clap:Help::val: next_line...No
DEBUG:clap:write_spaces!: num=4
DEBUG:clap:Help::help;
DEBUG:clap:Help::help: Next Line...false
DEBUG:clap:Help::help: Too long...No
stem 0.1.0
Sharlatan 
Collecting system level information such as hardware and OS stats.

USAGE:
    stem

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

[evanjs]

I was able to work around this by specifying _only_ the name in yml and the remaining properties via the crate! macros.
Not sure what other combinations work, but I feel like what is happening should at least be more clear. Between this and the indentation thing I've spent quite some time confused as the app compiles fine but the yml might completely be ignored.

[CreepySkeleton]

I would say this is how it's supposed to work.

• No field - no version/auther/about/etc at all
• version: crate_version!() - derive it from Cargo.toml
• The name field is mandatory, you can't omit it. Full stop. If you want it to be derived - use name: crate_name!()

But I agree this should be documented better.

[alexschrod]

I'm in a somewhat similar situation, didn't feel different enough to create a whole new issue. I do this in my code:

let matches = App::from_yaml(yaml)
    .name(Game::GAME_ID)
    .version(Game::VERSION)
    .author(Game::AUTHOR)
    .about(Game::DESCRIPTION)
    .get_matches();

Since I set all those there, I figured I could leave them out of the YAML file. But no. name is mandatory in the YAML, even if you provide it some other way. So for now, my YAML file looks like this:

name: required_for_some_reason_even_though_it_is_defined_in_code
args:
  - ...

😜

[CreepySkeleton]

@alexschrod Well, this is inevitable. clap::App needs a name because it's a central concept - there's no application without a name. So, in order to being able to create an App, the YAML loader needs a name. There's also no way for it to know that you are going to override it in your code one line below.