thiserror_impl/
fallback.rs

1use crate::expand::call_site_ident;
2use crate::private;
3use proc_macro2::TokenStream;
4use quote::quote;
5use syn::DeriveInput;
6
7pub(crate) fn expand(input: &DeriveInput, error: syn::Error) -> TokenStream {
8    let ty = call_site_ident(&input.ident);
9    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
10
11    let error = error.to_compile_error();
12
13    {
    let mut _s = ::quote::__private::TokenStream::new();
    ::quote::ToTokens::to_tokens(&error, &mut _s);
    ::quote::__private::push_pound(&mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Bracket,
        {
            let mut _s = ::quote::__private::TokenStream::new();
            ::quote::__private::push_ident(&mut _s, "allow");
            ::quote::__private::push_group(&mut _s,
                ::quote::__private::Delimiter::Parenthesis,
                {
                    let mut _s = ::quote::__private::TokenStream::new();
                    ::quote::__private::push_ident(&mut _s,
                        "unused_qualifications");
                    _s
                });
            _s
        });
    ::quote::__private::push_pound(&mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Bracket,
        {
            let mut _s = ::quote::__private::TokenStream::new();
            ::quote::__private::push_ident(&mut _s, "automatically_derived");
            _s
        });
    ::quote::__private::push_ident(&mut _s, "impl");
    ::quote::ToTokens::to_tokens(&impl_generics, &mut _s);
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "thiserror");
    ::quote::__private::push_colon2(&mut _s);
    ::quote::ToTokens::to_tokens(&private, &mut _s);
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "Error");
    ::quote::__private::push_ident(&mut _s, "for");
    ::quote::ToTokens::to_tokens(&ty, &mut _s);
    ::quote::ToTokens::to_tokens(&ty_generics, &mut _s);
    ::quote::ToTokens::to_tokens(&where_clause, &mut _s);
    ::quote::__private::push_ident(&mut _s, "where");
    ::quote::__private::push_ident(&mut _s, "for");
    ::quote::__private::push_lt(&mut _s);
    ::quote::__private::push_lifetime(&mut _s, "\'workaround");
    ::quote::__private::push_gt(&mut _s);
    ::quote::ToTokens::to_tokens(&ty, &mut _s);
    ::quote::ToTokens::to_tokens(&ty_generics, &mut _s);
    ::quote::__private::push_colon(&mut _s);
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "core");
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "fmt");
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "Debug");
    ::quote::__private::push_comma(&mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Brace,
        ::quote::__private::TokenStream::new());
    ::quote::__private::push_pound(&mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Bracket,
        {
            let mut _s = ::quote::__private::TokenStream::new();
            ::quote::__private::push_ident(&mut _s, "allow");
            ::quote::__private::push_group(&mut _s,
                ::quote::__private::Delimiter::Parenthesis,
                {
                    let mut _s = ::quote::__private::TokenStream::new();
                    ::quote::__private::push_ident(&mut _s,
                        "unused_qualifications");
                    _s
                });
            _s
        });
    ::quote::__private::push_pound(&mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Bracket,
        {
            let mut _s = ::quote::__private::TokenStream::new();
            ::quote::__private::push_ident(&mut _s, "automatically_derived");
            _s
        });
    ::quote::__private::push_ident(&mut _s, "impl");
    ::quote::ToTokens::to_tokens(&impl_generics, &mut _s);
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "core");
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "fmt");
    ::quote::__private::push_colon2(&mut _s);
    ::quote::__private::push_ident(&mut _s, "Display");
    ::quote::__private::push_ident(&mut _s, "for");
    ::quote::ToTokens::to_tokens(&ty, &mut _s);
    ::quote::ToTokens::to_tokens(&ty_generics, &mut _s);
    ::quote::ToTokens::to_tokens(&where_clause, &mut _s);
    ::quote::__private::push_group(&mut _s,
        ::quote::__private::Delimiter::Brace,
        {
            let mut _s = ::quote::__private::TokenStream::new();
            ::quote::__private::push_ident(&mut _s, "fn");
            ::quote::__private::push_ident(&mut _s, "fmt");
            ::quote::__private::push_group(&mut _s,
                ::quote::__private::Delimiter::Parenthesis,
                {
                    let mut _s = ::quote::__private::TokenStream::new();
                    ::quote::__private::push_and(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "self");
                    ::quote::__private::push_comma(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "__formatter");
                    ::quote::__private::push_colon(&mut _s);
                    ::quote::__private::push_and(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "mut");
                    ::quote::__private::push_colon2(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "core");
                    ::quote::__private::push_colon2(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "fmt");
                    ::quote::__private::push_colon2(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "Formatter");
                    _s
                });
            ::quote::__private::push_rarrow(&mut _s);
            ::quote::__private::push_colon2(&mut _s);
            ::quote::__private::push_ident(&mut _s, "core");
            ::quote::__private::push_colon2(&mut _s);
            ::quote::__private::push_ident(&mut _s, "fmt");
            ::quote::__private::push_colon2(&mut _s);
            ::quote::__private::push_ident(&mut _s, "Result");
            ::quote::__private::push_group(&mut _s,
                ::quote::__private::Delimiter::Brace,
                {
                    let mut _s = ::quote::__private::TokenStream::new();
                    ::quote::__private::push_colon2(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "core");
                    ::quote::__private::push_colon2(&mut _s);
                    ::quote::__private::push_ident(&mut _s, "unreachable");
                    ::quote::__private::push_bang(&mut _s);
                    ::quote::__private::push_group(&mut _s,
                        ::quote::__private::Delimiter::Parenthesis,
                        ::quote::__private::TokenStream::new());
                    _s
                });
            _s
        });
    _s
}quote! {
14        #error
15
16        #[allow(unused_qualifications)]
17        #[automatically_derived]
18        impl #impl_generics ::thiserror::#private::Error for #ty #ty_generics #where_clause
19        where
20            // Work around trivial bounds being unstable.
21            // https://github.com/rust-lang/rust/issues/48214
22            for<'workaround> #ty #ty_generics: ::core::fmt::Debug,
23        {}
24
25        #[allow(unused_qualifications)]
26        #[automatically_derived]
27        impl #impl_generics ::core::fmt::Display for #ty #ty_generics #where_clause {
28            fn fmt(&self, __formatter: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
29                ::core::unreachable!()
30            }
31        }
32    }
33}