CLI: Reject invalid argument values rather than ignore them

[axelchalon]

Previously (since the CLI port to clap), passing invalid values (e.g. providing a string value to an argument that expects a u32) was failing silently and was processed just like if the argument hadn't been entered.

Now, Parity explicitly refuses to launch if Clap cannot parse the value into the expected type.

$ parity --cache=asd                            
error: Invalid value: The argument 'asd' isn't a valid value

[debris]

it would be better to unwrap the value here rather then calling ok() later.

		match $e {
 			Err(clap_error @ ClapError { kind: ClapErrorKind::ValueValidation, .. }) => {
 				return Err(clap_error);
 			},
 			Ok(e) => e
         }

[arkpar]

What's the reason to ignore errors other than ClapErrorKind::ValueValidation btw?

[axelchalon]

@arkpar the clap macro value_t! (whose result I feed into the return_if_parse_error! macro) yields a Result ; the error can be either ClapErrorKind::ArgumentNotFound or ClapErrorKind::ValueValidation. If it's ArgumentNotFound then the value of the argument in the struct should be None.

@debris I thought about it but figured it'd be better if the macro didn't convert to Option for separation of concern, but I agree it'd be better for DRY. $e can be either ClapErrorKind::ValueValidation error, or ClapErrorKind::ArgumentNotFound error, or Ok(...) ; in the two latter cases this is normal behaviour and we want to convert it to Option; I guess the following would be good?

match $e {
 			Err(clap_error @ ClapError { kind: ClapErrorKind::ValueValidation, .. }) => {
 				return Err(clap_error);
 			},
 			_ => $e.ok()
         }

[debris]

yes, just describe it in the comment ;)