1 files changed, 59 insertions, 0 deletions
diff --git a/third_party/rust/derive_more-impl/src/into_iterator.rs b/third_party/rust/derive_more-impl/src/into_iterator.rs
new file mode 100644
index 0000000000..f10dbf7a0b
--- /dev/null
+++ b/third_party/rust/derive_more-impl/src/into_iterator.rs
@@ -0,0 +1,59 @@
+use crate::utils::{
+    add_extra_generic_param, add_extra_ty_param_bound_ref, SingleFieldData, State,
+};
+use proc_macro2::TokenStream;
+use quote::{quote, ToTokens};
+use syn::{parse::Result, DeriveInput};
+
+/// Provides the hook to expand `#[derive(IntoIterator)]` into an implementation of `IntoIterator`
+pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
+    let state =
+        State::with_field_ignore_and_refs(input, trait_name, "into_iterator".into())?;
+    let SingleFieldData {
+        input_type,
+        info,
+        field_type,
+        member,
+        trait_path,
+        ..
+    } = state.assert_single_enabled_field();
+
+    let mut tokens = TokenStream::new();
+
+    for ref_type in info.ref_types() {
+        let reference = ref_type.reference();
+        let lifetime = ref_type.lifetime();
+        let reference_with_lifetime = ref_type.reference_with_lifetime();
+
+        let generics_impl;
+        let generics =
+            add_extra_ty_param_bound_ref(&input.generics, trait_path, ref_type);
+        let (_, ty_generics, where_clause) = generics.split_for_impl();
+        let (impl_generics, _, _) = if ref_type.is_ref() {
+            generics_impl = add_extra_generic_param(&generics, lifetime.clone());
+            generics_impl.split_for_impl()
+        } else {
+            generics.split_for_impl()
+        };
+        // let generics = add_extra_ty_param_bound(&input.generics, trait_path);
+        let casted_trait = &quote! {
+            <#reference_with_lifetime #field_type as #trait_path>
+        };
+        let into_iterator = quote! {
+            #[automatically_derived]
+            impl #impl_generics #trait_path for #reference_with_lifetime #input_type #ty_generics
+                 #where_clause
+            {
+                type Item = #casted_trait::Item;
+                type IntoIter = #casted_trait::IntoIter;
+
+                #[inline]
+                fn into_iter(self) -> Self::IntoIter {
+                    #casted_trait::into_iter(#reference #member)
+                }
+            }
+        };
+        into_iterator.to_tokens(&mut tokens);
+    }
+    Ok(tokens)
+}