1 files changed, 142 insertions, 0 deletions
diff --git a/vendor/derive_more/src/from.rs b/vendor/derive_more/src/from.rs
new file mode 100644
index 000000000..56ff5bcf9
--- /dev/null
+++ b/vendor/derive_more/src/from.rs
@@ -0,0 +1,142 @@
+use std::iter;
+
+use proc_macro2::{Span, TokenStream};
+use quote::{quote, ToTokens};
+use syn::{parse::Result, DeriveInput, Ident, Index};
+
+use crate::utils::{
+    add_where_clauses_for_new_ident, AttrParams, DeriveType, HashMap, MultiFieldData,
+    RefType, State,
+};
+
+/// Provides the hook to expand `#[derive(From)]` into an implementation of `From`
+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!["forward", "ignore"],
+            variant: vec!["forward", "ignore", "types"],
+            struct_: vec!["forward", "types"],
+            field: vec!["forward"],
+        },
+    )?;
+    if state.derive_type == DeriveType::Enum {
+        Ok(enum_from(input, state))
+    } else {
+        Ok(struct_from(input, &state))
+    }
+}
+
+pub fn struct_from(input: &DeriveInput, state: &State) -> TokenStream {
+    let multi_field_data = state.enabled_fields_data();
+    let MultiFieldData {
+        fields,
+        variant_info,
+        infos,
+        input_type,
+        trait_path,
+        ..
+    } = multi_field_data.clone();
+
+    let additional_types = variant_info.additional_types(RefType::No);
+    let mut impls = Vec::with_capacity(additional_types.len() + 1);
+    for explicit_type in iter::once(None).chain(additional_types.iter().map(Some)) {
+        let mut new_generics = input.generics.clone();
+
+        let mut initializers = Vec::with_capacity(infos.len());
+        let mut from_types = Vec::with_capacity(infos.len());
+        for (i, (info, field)) in infos.iter().zip(fields.iter()).enumerate() {
+            let field_type = &field.ty;
+            let variable = if fields.len() == 1 {
+                quote! { original }
+            } else {
+                let tuple_index = Index::from(i);
+                quote! { original.#tuple_index }
+            };
+            if let Some(type_) = explicit_type {
+                initializers.push(quote! {
+                    <#field_type as #trait_path<#type_>>::from(#variable)
+                });
+                from_types.push(quote! { #type_ });
+            } else if info.forward {
+                let type_param =
+                    &Ident::new(&format!("__FromT{}", i), Span::call_site());
+                let sub_trait_path = quote! { #trait_path<#type_param> };
+                let type_where_clauses = quote! {
+                    where #field_type: #sub_trait_path
+                };
+                new_generics = add_where_clauses_for_new_ident(
+                    &new_generics,
+                    &[field],
+                    type_param,
+                    type_where_clauses,
+                    true,
+                );
+                let casted_trait = quote! { <#field_type as #sub_trait_path> };
+                initializers.push(quote! { #casted_trait::from(#variable) });
+                from_types.push(quote! { #type_param });
+            } else {
+                initializers.push(variable);
+                from_types.push(quote! { #field_type });
+            }
+        }
+
+        let body = multi_field_data.initializer(&initializers);
+        let (impl_generics, _, where_clause) = new_generics.split_for_impl();
+        let (_, ty_generics, _) = input.generics.split_for_impl();
+
+        impls.push(quote! {
+            #[automatically_derived]
+            impl#impl_generics #trait_path<(#(#from_types),*)> for
+                #input_type#ty_generics #where_clause {
+
+                #[inline]
+                fn from(original: (#(#from_types),*)) -> #input_type#ty_generics {
+                    #body
+                }
+            }
+        });
+    }
+
+    quote! { #( #impls )* }
+}
+
+fn enum_from(input: &DeriveInput, state: State) -> TokenStream {
+    let mut tokens = TokenStream::new();
+
+    let mut variants_per_types = HashMap::default();
+    for variant_state in state.enabled_variant_data().variant_states {
+        let multi_field_data = variant_state.enabled_fields_data();
+        let MultiFieldData { field_types, .. } = multi_field_data.clone();
+        variants_per_types
+            .entry(field_types.clone())
+            .or_insert_with(Vec::new)
+            .push(variant_state);
+    }
+    for (ref field_types, ref variant_states) in variants_per_types {
+        for variant_state in variant_states {
+            let multi_field_data = variant_state.enabled_fields_data();
+            let MultiFieldData {
+                variant_info,
+                infos,
+                ..
+            } = multi_field_data.clone();
+            // If there would be a conflict on a empty tuple derive, ignore the
+            // variants that are not explicitly enabled or have explicitly enabled
+            // or disabled fields
+            if field_types.is_empty()
+                && variant_states.len() > 1
+                && !std::iter::once(variant_info)
+                    .chain(infos)
+                    .any(|info| info.info.enabled.is_some())
+            {
+                continue;
+            }
+            struct_from(input, variant_state).to_tokens(&mut tokens);
+        }
+    }
+    tokens
+}