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use darling::FromVariant;
use syn::{spanned::Spanned, Expr, ExprLit, LitInt};
#[derive(FromVariant)]
#[darling(from_ident, attributes(hello))]
#[allow(dead_code)]
pub struct Lorem {
ident: syn::Ident,
into: Option<bool>,
skip: Option<bool>,
discriminant: Option<syn::Expr>,
fields: darling::ast::Fields<syn::Type>,
}
impl From<syn::Ident> for Lorem {
fn from(ident: syn::Ident) -> Self {
Lorem {
ident,
into: Default::default(),
skip: Default::default(),
discriminant: None,
fields: darling::ast::Style::Unit.into(),
}
}
}
#[test]
fn discriminant() {
let input: syn::DeriveInput = syn::parse_str(
r#"
pub enum Test {
Works = 1,
AlsoWorks = 2,
}
"#,
)
.unwrap();
let span = input.span();
if let syn::Data::Enum(enm) = input.data {
let lorem = Lorem::from_variant(
enm.variants
.first()
.expect("Hardcoded input has one variant"),
)
.expect("FromVariant can process the discriminant");
assert_eq!(
lorem.discriminant,
Some(Expr::Lit(ExprLit {
attrs: vec![],
lit: LitInt::new("1", span).into(),
}))
)
} else {
panic!("Data should be enum");
}
}