rustc_ap_rustc_macros/
type_foldable.rs

1use quote::quote;
2
3pub fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
4    if let syn::Data::Union(_) = s.ast().data {
5        panic!("cannot derive on union")
6    }
7
8    s.add_bounds(synstructure::AddBounds::Generics);
9    let body_visit = s.each(|bind| {
10        quote! {
11            ::rustc_middle::ty::fold::TypeFoldable::visit_with(#bind, __folder)?;
12        }
13    });
14    s.bind_with(|_| synstructure::BindStyle::Move);
15    let body_fold = s.each_variant(|vi| {
16        let bindings = vi.bindings();
17        vi.construct(|_, index| {
18            let bind = &bindings[index];
19            quote! {
20                ::rustc_middle::ty::fold::TypeFoldable::fold_with(#bind, __folder)
21            }
22        })
23    });
24
25    s.bound_impl(
26        quote!(::rustc_middle::ty::fold::TypeFoldable<'tcx>),
27        quote! {
28            fn super_fold_with<__F: ::rustc_middle::ty::fold::TypeFolder<'tcx>>(
29                self,
30                __folder: &mut __F
31            ) -> Self {
32                match self { #body_fold }
33            }
34
35            fn super_visit_with<__F: ::rustc_middle::ty::fold::TypeVisitor<'tcx>>(
36                &self,
37                __folder: &mut __F
38            ) -> ::std::ops::ControlFlow<__F::BreakTy> {
39                match *self { #body_visit }
40                ::std::ops::ControlFlow::CONTINUE
41            }
42        },
43    )
44}
rustc_ap_rustc_macros/type_foldable.rs

rustc_ap_rustc_macros/
type_foldable.rs
