FromMeta attribute for value which can be simple flag or String.

[chtotut]

Hi, I want to create attribute for:

#[derive(Test)]
pub struct Struct {
    #[test(value)]
    a: u8,
    #[test(value = "some expression")]
    b: u8,
}

value can be simple flag or String.
Is it possible?

[TedDriggs]

Would the type of value be an enum? If so, then this feels like a duplicate of #63, which would add support for associating the basic form of an enum with a specific variant.

Otherwise, you can implement this yourself without too much difficulty by filling in the following:

impl FromMeta for YourValue {
    fn from_word() -> darling::Result<Self> {}
    fn from_str(s: &str) -> darling::Result<Self> {}
}