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use proc_macro::TokenStream;

use syn::parse_macro_input;
use syn::spanned::Spanned;

#[proc_macro_attribute]
pub fn not_a_closure(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let orig = item.clone();
    let expr = parse_macro_input!(item as syn::Expr);

    if let syn::Expr::Closure(expr_closure) = expr {
        syn::Error::new(expr_closure.span(), "DON'T NEED NO STINKEN LAMBDA")
            .to_compile_error()
            .into()
    } else {
        orig
    }
}