Argument that requires another argument in an argument group gives empty error

[crat0z]

Please complete the following tasks

• I have searched the discussions
• I have searched the open and rejected issues

Rust Version

rustc 1.64.0-nightly (9067d5277 2022-07-28)

Clap Version

3.2.15

Minimal reproducible code

use clap::{ArgGroup, Parser};

#[derive(Parser, Debug)]
#[clap(author, version, about, long_about = None)]
#[clap(group(ArgGroup::new("either_or_both").multiple(true).required(true).args(&["first", "second"])))]
struct Args {
    #[clap(short, long, requires("first"))]
    require_first: bool,
    #[clap(short, long)]
    first: bool,
    #[clap(short, long)]
    second: bool,
}
fn main() {
    let args: Args = Args::parse();

    dbg!(args);
}

Steps to reproduce the bug with the above code

cargo run -- --require-first --second

Actual Behaviour

error: The following required arguments were not provided:

USAGE:
    clap_example --require-first <--first|--second>

For more information try --help

Expected Behaviour

Error message should provide context, e.g.

error: The following required arguments were not provided:
    --first

USAGE:
    clap_example --require-first <--first|--second>

For more information try --help

Additional Context

Removing the multiple(true) part unintuitively works:

[src/main.rs:17] args = Args {
    require_first: true,
    first: false,
    second: true,
}

This leads me to believe I'm probably misusing ArgGroup in this case, however the error message should still say something IMO.

Debug Output

[      clap::builder::command] 	Command::_do_parse
[      clap::builder::command] 	Command::_build: name="clap_example"
[      clap::builder::command] 	Command::_propagate:clap_example
[      clap::builder::command] 	Command::_check_help_and_version: clap_example
[      clap::builder::command] 	Command::_propagate_global_args:clap_example
[      clap::builder::command] 	Command::_derive_display_order:clap_example
[clap::builder::debug_asserts] 	Command::_debug_asserts
[clap::builder::debug_asserts] 	Arg::_debug_asserts:help
[clap::builder::debug_asserts] 	Arg::_debug_asserts:version
[clap::builder::debug_asserts] 	Arg::_debug_asserts:require-first
[clap::builder::debug_asserts] 	Arg::_debug_asserts:first
[clap::builder::debug_asserts] 	Arg::_debug_asserts:second
[clap::builder::debug_asserts] 	Command::_verify_positionals
[        clap::parser::parser] 	Parser::get_matches_with
[        clap::parser::parser] 	Parser::get_matches_with: Begin parsing 'RawOsStr("--require-first")' ([45, 45, 114, 101, 113, 117, 105, 114, 101, 45, 102, 105, 114, 115, 116])
[        clap::parser::parser] 	Parser::possible_subcommand: arg=Ok("--require-first")
[        clap::parser::parser] 	Parser::get_matches_with: sc=None
[        clap::parser::parser] 	Parser::parse_long_arg
[        clap::parser::parser] 	Parser::parse_long_arg: Does it contain '='...
[        clap::parser::parser] 	Parser::parse_long_arg: Found valid arg or flag '--require-first'
[        clap::parser::parser] 	Parser::parse_long_arg("require-first"): Presence validated
[        clap::parser::parser] 	Parser::react action=IncOccurrence, identifier=Some(Long), source=CommandLine
[        clap::parser::parser] 	Parser::react: cur_idx:=1
[        clap::parser::parser] 	Parser::remove_overrides: id=require-first
[   clap::parser::arg_matcher] 	ArgMatcher::start_occurrence_of_arg: id=require-first
[      clap::builder::command] 	Command::groups_for_arg: id=require-first
[        clap::parser::parser] 	Parser::get_matches_with: After parse_long_arg ValuesDone
[        clap::parser::parser] 	Parser::get_matches_with: Begin parsing 'RawOsStr("--second")' ([45, 45, 115, 101, 99, 111, 110, 100])
[        clap::parser::parser] 	Parser::possible_subcommand: arg=Ok("--second")
[        clap::parser::parser] 	Parser::get_matches_with: sc=None
[        clap::parser::parser] 	Parser::parse_long_arg
[        clap::parser::parser] 	Parser::parse_long_arg: Does it contain '='...
[        clap::parser::parser] 	Parser::parse_long_arg: Found valid arg or flag '--second'
[        clap::parser::parser] 	Parser::parse_long_arg("second"): Presence validated
[        clap::parser::parser] 	Parser::react action=IncOccurrence, identifier=Some(Long), source=CommandLine
[        clap::parser::parser] 	Parser::react: cur_idx:=2
[        clap::parser::parser] 	Parser::remove_overrides: id=second
[   clap::parser::arg_matcher] 	ArgMatcher::start_occurrence_of_arg: id=second
[      clap::builder::command] 	Command::groups_for_arg: id=second
[   clap::parser::arg_matcher] 	ArgMatcher::start_occurrence_of_group: id=either_or_both
[        clap::parser::parser] 	Parser::get_matches_with: After parse_long_arg ValuesDone
[        clap::parser::parser] 	Parser::add_defaults
[        clap::parser::parser] 	Parser::add_defaults:iter:help:
[        clap::parser::parser] 	Parser::add_default_value:iter:help: doesn't have default missing vals
[        clap::parser::parser] 	Parser::add_default_value: doesn't have conditional defaults
[        clap::parser::parser] 	Parser::add_default_value:iter:help: doesn't have default vals
[        clap::parser::parser] 	Parser::add_defaults:iter:version:
[        clap::parser::parser] 	Parser::add_default_value:iter:version: doesn't have default missing vals
[        clap::parser::parser] 	Parser::add_default_value: doesn't have conditional defaults
[        clap::parser::parser] 	Parser::add_default_value:iter:version: doesn't have default vals
[        clap::parser::parser] 	Parser::add_defaults:iter:require-first:
[        clap::parser::parser] 	Parser::add_default_value:iter:require-first: doesn't have default missing vals
[        clap::parser::parser] 	Parser::add_default_value: doesn't have conditional defaults
[        clap::parser::parser] 	Parser::add_default_value:iter:require-first: doesn't have default vals
[        clap::parser::parser] 	Parser::add_defaults:iter:first:
[        clap::parser::parser] 	Parser::add_default_value:iter:first: doesn't have default missing vals
[        clap::parser::parser] 	Parser::add_default_value: doesn't have conditional defaults
[        clap::parser::parser] 	Parser::add_default_value:iter:first: doesn't have default vals
[        clap::parser::parser] 	Parser::add_defaults:iter:second:
[        clap::parser::parser] 	Parser::add_default_value:iter:second: doesn't have default missing vals
[        clap::parser::parser] 	Parser::add_default_value: doesn't have conditional defaults
[        clap::parser::parser] 	Parser::add_default_value:iter:second: doesn't have default vals
[     clap::parser::validator] 	Validator::validate
[     clap::parser::validator] 	Validator::validate_conflicts
[     clap::parser::validator] 	Validator::validate_exclusive
[     clap::parser::validator] 	Validator::validate_exclusive:iter:require-first
[     clap::parser::validator] 	Validator::validate_exclusive:iter:second
[     clap::parser::validator] 	Validator::validate_exclusive:iter:either_or_both
[     clap::parser::validator] 	Validator::validate_conflicts::iter: id=require-first
[     clap::parser::validator] 	Conflicts::gather_conflicts: arg=require-first
[      clap::builder::command] 	Command::groups_for_arg: id=require-first
[     clap::parser::validator] 	Conflicts::gather_direct_conflicts id=require-first, conflicts=[]
[      clap::builder::command] 	Command::groups_for_arg: id=second
[     clap::parser::validator] 	Conflicts::gather_direct_conflicts id=second, conflicts=[]
[     clap::parser::validator] 	Conflicts::gather_direct_conflicts id=either_or_both, conflicts=[]
[     clap::parser::validator] 	Conflicts::gather_conflicts: conflicts=[]
[     clap::parser::validator] 	Validator::validate_conflicts::iter: id=second
[     clap::parser::validator] 	Conflicts::gather_conflicts: arg=second
[     clap::parser::validator] 	Conflicts::gather_conflicts: conflicts=[]
[     clap::parser::validator] 	Validator::validate_required: required=ChildGraph([Child { id: either_or_both, children: [] }])
[     clap::parser::validator] 	Validator::gather_requires
[     clap::parser::validator] 	Validator::gather_requires:iter:require-first
[     clap::parser::validator] 	Validator::gather_requires:iter:second
[     clap::parser::validator] 	Validator::gather_requires:iter:either_or_both
[     clap::parser::validator] 	Validator::gather_requires:iter:either_or_both:group
[     clap::parser::validator] 	Validator::validate_required: is_exclusive_present=false
[     clap::parser::validator] 	Validator::validate_required:iter:aog=first
[     clap::parser::validator] 	Validator::validate_required:iter: This is an arg
[     clap::parser::validator] 	Validator::is_missing_required_ok: first
[     clap::parser::validator] 	Conflicts::gather_conflicts: arg=first
[      clap::builder::command] 	Command::groups_for_arg: id=first
[     clap::parser::validator] 	Conflicts::gather_direct_conflicts id=first, conflicts=[]
[     clap::parser::validator] 	Conflicts::gather_conflicts: conflicts=[]
[     clap::parser::validator] 	Validator::missing_required_error; incl=[]
[     clap::parser::validator] 	Validator::missing_required_error: reqs=ChildGraph([Child { id: either_or_both, children: [] }, Child { id: first, children: [] }])
[         clap::output::usage] 	Usage::get_required_usage_from: incls=[], matcher=true, incl_last=true
[         clap::output::usage] 	Usage::get_required_usage_from: unrolled_reqs={either_or_both, first}
[      clap::builder::command] 	Command::unroll_args_in_group: group=either_or_both
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=first
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=second
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group: group=either_or_both
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=first
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=second
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[         clap::output::usage] 	Usage::get_required_usage_from: ret_val={}
[     clap::parser::validator] 	Validator::missing_required_error: req_args=[]
[         clap::output::usage] 	Usage::create_usage_with_title
[         clap::output::usage] 	Usage::create_usage_no_title
[         clap::output::usage] 	Usage::create_smart_usage
[         clap::output::usage] 	Usage::get_required_usage_from: incls=[require-first, second, either_or_both], matcher=false, incl_last=true
[         clap::output::usage] 	Usage::get_required_usage_from: unrolled_reqs={either_or_both, first}
[      clap::builder::command] 	Command::unroll_args_in_group: group=either_or_both
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=first
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=second
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[         clap::output::usage] 	Usage::get_required_usage_from:iter:require-first
[      clap::builder::command] 	Command::unroll_args_in_group: group=either_or_both
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=first
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=second
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[         clap::output::usage] 	Usage::get_required_usage_from: ret_val={"--require-first", "<--first|--second>"}
[      clap::builder::command] 	Command::color: Color setting...
[      clap::builder::command] 	Auto
error: The following required arguments were not provided:

USAGE:
    clap_example --require-first <--first|--second>

For more information try --help

[epage]

If I read the code correctly, when we generate the error, we know which argument is required but we don't want to report just that one required argument but all of them, so instead of forcing that argument to be present, we delegate to a "missing required" calculator. For some reason it is removing "first" from the list

Relevant log entry

[         clap::output::usage] 	Usage::get_required_usage_from: unrolled_reqs={either_or_both, first}
[      clap::builder::command] 	Command::unroll_args_in_group: group=either_or_both
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=first
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=second
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group: group=either_or_both
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=first
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[      clap::builder::command] 	Command::unroll_args_in_group:iter: entity=second
[      clap::builder::command] 	Command::unroll_args_in_group:iter: this is an arg
[         clap::output::usage] 	Usage::get_required_usage_from: ret_val={}

[epage]

Say you just run cargo run (no args to the command). We could potentially show in the required --first, --second, and <--first|--second>. We work to de-duplicate this but in doing so, I think we have a bug that is removing --first when the requirement on <--first|--second> is resolved, causing it to not show up.

[epage]

v3.2.16 is released with the fix for this