improve error message for explicitly empty appliesTo

[cdisselkoen]

Category

Error message improvements

Describe the feature you'd like to request

For the following schema:

action Read appliesTo {
  principal: [],
  resource: [],
};

The error message when parsing this is currently (as of 4.2.2)

  × error parsing schema: An empty list was passed

This could be more clear. It also doesn't have any locating information, like a source location, or an indication of which action had the parsing problem.

Describe alternatives you've considered

N/A

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

[shaobo-he-aws]

It seems a deeper issue is that parse errors thrown by lalrpop do not get access to the source string and hence cannot properly implement the label method.

[john-h-kastner-aws]

See #948 and #977 for missing source locations in cedar schema parsing errors

[cdisselkoen]

We did adjust the lalrpop for the policy format to provide the source string (#516). Perhaps we need the same change in the schema-format lalrpop file.

[shaobo-he-aws]

We did adjust the lalrpop for the policy format to provide the source string (#516). Perhaps we need the same change in the schema-format lalrpop file.

There's certain part missing in the Cedar schema parser. I'm looking into it and see if we can reuse code for both parsers.