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#![doc = include_str!("../README.md")]

use proc_macro::TokenStream;

struct SignatureWithSemicolon {
    attrs: Vec<syn::Attribute>,
    vis: syn::Visibility,
    sig: syn::Signature,
    _semicolon_token: syn::Token![;],
}

impl syn::parse::Parse for SignatureWithSemicolon {
    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
        let outer_attrs = input.call(syn::Attribute::parse_outer)?;
        let vis = input.parse()?;
        let sig = input.parse()?;

        Ok(Self {
            attrs: outer_attrs,
            vis,
            sig,
            _semicolon_token: input.parse()?,
        })
    }
}

#[proc_macro_attribute]
pub fn unimpl(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let input = syn::parse_macro_input!(item as SignatureWithSemicolon);

    let fn_name = input.sig.ident.to_string();

    let attrs = input.attrs;
    let signature = input.sig;
    let vis = input.vis;
    let output = quote::quote! {
        #(#attrs)*
        #vis
        #signature
        {
            unimplemented!(#fn_name);
        }
    };

    output.into()
}