[unsafe-fields] adding enum rule into unsafe-fields macro

[dacozai]

#1957: support enum in [unsafe-fields]

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.46%. Comparing base (13c11f8) to head (bc99e92).
Report is 3 commits behind head on main.

Additional details and impacted files

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##             main    #2034   +/-   ##
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  Coverage   89.46%   89.46%           
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  Files          16       16           
  Lines        5838     5838           
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  Hits         5223     5223           
  Misses        615      615           

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[dacozai]

I am sorry that I should clarify this in the first place.
I am not sure that the below are goals as well

unsafe_fields {
    enum FooEnum {
        #[unsafe]
        A,
        B,
        #[unsafe]
        C(i32, String),
    }
}

1. I am not sure unit variant is possible to do so. Maybe the input name will be A and the input type will be FooEnum::A.
2. I am still surveying the tuple variant. Although I don't know if it can be achieved or not, it seems achievable to me.

Thank you 🙏🏻

[jswrenn]

1. Don't worry about unit variants — this crate is about supporting unsafe fields, not unsafe variants!
2. Sounds good. We definitely want support for tuple-like structs and fields.

[dacozai]

Hi @jswrenn,
After few days of surveying, I still failed to achieve 😭
I posted a question in the forum to check if I missed anything. If there is any direction that you can guide, please let me know.
Appreciate your help. Many thanks.