confusing "'x.py' requires a subcommand but one was not provided" error

[lolbinarycat]

this error is printed not only when no subcommand is provided, but also when an invalid subcommand is provided.

example: ./x nonsensesubcommand or a typo like ./x fmtt.

either the error message should be changed to reflect the fact that it is printed in two situations, or these two situations should produce different error messages.

[onur-ozkan]

this error is printed not only when no subcommand is provided,

In this case --help should be printed.

[clubby789]

I think this is because our Flags struct (which we use clap to derive a parser from) ends with

rust/src/bootstrap/src/core/config/flags.rs

Lines 177 to 179 in c926476

	/// arguments passed to subcommands
	#[arg(global = true, last(true), value_name = "ARGS")]
	pub free_args: Vec<String>,

This consumes the incorrect subcommand, so Clap believes there isn't one and prints this message