max_values confusingly returns ErrorKind::UnknownArgument when too many arguments are provided

[SilvanCodes]

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Clap Version

3.1.15

Describe your use case

I want to limit the maximum given arguments with a proper error message for the user when too many arguments are provided.

Describe the solution you'd like

Instead of ErrorKind::UnknownArgument I would like max_values to return a new error kind like ErrorKind::TooManyValues mirroring the behavior of min_values with its error kind ErrorKind::TooFewValues.

Alternatives, if applicable

No response

Additional Context

No response

[epage]

With TooFewValues, there is a definitive case for us to identify and report an error: the parser was looking for more values and didn't see them.

TooManyValues is a bit trickier because the parser exhausted one argument and is processing the next, finding it doesn't exist. We'd need to match against a trailing argument that took a value but there are no more positional or subcommands afterwards. The error also might not make sense for an argument that just takes one value. Or maybe it does.

Then it comes to the implementation. Our parser isn't in a great state right now though hopefully some in going refactors will improve things a bit.

This isn't a "no" but that parts of the design need to be figured out and that we might wait for some refactorings before its practical to implement.