Function has_existing_default

rust/fory-derive/src/object/serializer.rs:26–39

(ast: &syn::DeriveInput, trait_name: &str)

use syn::Data;

fn has_existing_default(ast: &syn::DeriveInput, trait_name: &str) -> bool {
    ast.attrs.iter().any(|attr| {
        attr.path().is_ident("derive") && {
            let mut has_default = false;
            let _ = attr.parse_nested_meta(|meta| {
                if meta.path.is_ident(trait_name) {
                    has_default = true;
                }
                Ok(())
            });
            has_default
        }
    })
}

pub fn derive_serializer(
    ast: &syn::DeriveInput,