1 files changed, 58 insertions, 0 deletions
diff --git a/third_party/rust/derive_more/src/into.rs b/third_party/rust/derive_more/src/into.rs
new file mode 100644
index 0000000000..bb77e2336a
--- /dev/null
+++ b/third_party/rust/derive_more/src/into.rs
@@ -0,0 +1,58 @@
+use crate::utils::{add_extra_generic_param, AttrParams, MultiFieldData, State};
+use proc_macro2::TokenStream;
+use quote::{quote, ToTokens};
+use syn::{parse::Result, DeriveInput};
+
+/// Provides the hook to expand `#[derive(Into)]` into an implementation of `Into`
+pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
+    let state = State::with_attr_params(
+        input,
+        trait_name,
+        quote!(::core::convert),
+        trait_name.to_lowercase(),
+        AttrParams {
+            enum_: vec!["ignore", "owned", "ref", "ref_mut"],
+            variant: vec!["ignore", "owned", "ref", "ref_mut"],
+            struct_: vec!["ignore", "owned", "ref", "ref_mut"],
+            field: vec!["ignore"],
+        },
+    )?;
+    let MultiFieldData {
+        variant_info,
+        field_types,
+        field_idents,
+        input_type,
+        ..
+    } = state.enabled_fields_data();
+
+    let mut tokens = TokenStream::new();
+
+    for ref_type in variant_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 (_, ty_generics, where_clause) = input.generics.split_for_impl();
+        let (impl_generics, _, _) = if ref_type.is_ref() {
+            generics_impl = add_extra_generic_param(&input.generics, lifetime);
+            generics_impl.split_for_impl()
+        } else {
+            input.generics.split_for_impl()
+        };
+
+        let into = quote! {
+            impl#impl_generics ::core::convert::From<#reference_with_lifetime #input_type#ty_generics> for
+                (#(#reference_with_lifetime #field_types),*) #where_clause {
+
+                #[allow(unused_variables)]
+                #[inline]
+                fn from(original: #reference_with_lifetime #input_type#ty_generics) -> (#(#reference_with_lifetime #field_types),*) {
+                    (#(#reference original.#field_idents),*)
+                }
+            }
+        };
+        into.to_tokens(&mut tokens);
+    }
+    Ok(tokens)
+}