Implement #[serde(bound = "...")]

Author: daxpedda

src/trait_/deserialize.rs

@@ -3,14 +3,14 @@
 use std::{borrow::Cow, ops::Deref};
 
 use proc_macro2::{Span, TokenStream};
-use quote::quote;
+use quote::{format_ident, quote};
 use syn::{
 	punctuated::Punctuated, Attribute, DeriveInput, Ident, ImplGenerics, Meta, Path, Result,
 	TypeGenerics, WhereClause,
 };
 
 use super::serde;
-use crate::{util, DeriveTrait, Trait, TraitImpl, DERIVE_WHERE};
+use crate::{util, DeriveTrait, Trait, TraitImpl};
 
 /// [`TraitImpl`] for [`Deserialize`](https://docs.rs/serde/latest/serde/derive.Deserialize.html).
 #[derive(Eq, PartialEq)]
@@ -48,7 +48,8 @@ impl TraitImpl for Deserialize {
 	}
 
 	fn path(&self) -> Path {
-		util::path_from_root_and_strs(self.crate_(), &["Deserialize"])
+		let crate_ = self.crate_();
+		syn::parse2::<Path>(quote! { #crate_::Deserialize<'de> }).unwrap()
 	}
 
 	fn impl_item(
@@ -58,19 +59,16 @@ impl TraitImpl for Deserialize {
 		_: &ImplGenerics<'_>,
 		_: &Ident,
 		_: &TypeGenerics<'_>,
-		_: &Option<Cow<'_, WhereClause>>,
+		where_clause: &Option<Cow<'_, WhereClause>>,
 		_: TokenStream,
 	) -> TokenStream {
-		let derive_where = crate_
-			.map(Cow::Borrowed)
-			.unwrap_or_else(|| Cow::Owned(util::path_from_strs(&[DERIVE_WHERE])));
-		let serde = self.crate_();
-
-		quote! {
-			#[derive(#serde::Deserialize)]
-			#[#derive_where::derive_where_serde]
-			#full_item
-		}
+		serde::impl_item(
+			crate_,
+			&self.crate_(),
+			format_ident!("Deserialize"),
+			full_item,
+			where_clause,
+		)
 	}
 }
 

src/trait_/serde.rs

@@ -2,14 +2,18 @@
 //! [`Deserialize`](https://docs.rs/serde/latest/serde/derive.Deserialize.html) and
 //! [`Serialize`](https://docs.rs/serde/latest/serde/derive.Serialize.html).
 
-use proc_macro2::Span;
+use std::borrow::Cow;
+
+use proc_macro2::{Span, TokenStream};
+use quote::{quote, ToTokens};
 use syn::{
-	punctuated::Punctuated, spanned::Spanned, Attribute, Expr, ExprLit, Lit, Meta, Path, Token,
+	punctuated::Punctuated, spanned::Spanned, Attribute, DeriveInput, Expr, ExprLit, Ident, Lit,
+	Meta, Path, Token, WhereClause,
 };
 
-use crate::{Error, Result, Trait};
+use crate::{util, Error, Result, Trait, DERIVE_WHERE};
 
-/// Parses
+/// Parse `#[serde(crate = "...")]`.
 pub fn parse_derive_trait(
 	trait_: Trait,
 	attrs: &[Attribute],
@@ -71,3 +75,29 @@ pub fn parse_derive_trait(
 
 	Ok(crate_)
 }
+
+/// Implement Serde trait.
+pub fn impl_item(
+	derive_where: Option<&Path>,
+	serde: &Path,
+	trait_: Ident,
+	full_item: &DeriveInput,
+	where_clause: &Option<Cow<'_, WhereClause>>,
+) -> TokenStream {
+	let derive_where = derive_where
+		.map(Cow::Borrowed)
+		.unwrap_or_else(|| Cow::Owned(util::path_from_strs(&[DERIVE_WHERE])));
+
+	let bound = if let Some(where_clause) = where_clause {
+		where_clause.predicates.to_token_stream().to_string()
+	} else {
+		String::new()
+	};
+
+	quote! {
+		#[::core::prelude::v1::derive(#serde::#trait_)]
+		#[serde(bound = #bound)]
+		#[#derive_where::derive_where_serde]
+		#full_item
+	}
+}

src/trait_/serialize.rs

@@ -3,14 +3,14 @@
 use std::{borrow::Cow, ops::Deref};
 
 use proc_macro2::{Span, TokenStream};
-use quote::quote;
+use quote::format_ident;
 use syn::{
 	punctuated::Punctuated, Attribute, DeriveInput, Ident, ImplGenerics, Meta, Path, Result,
 	TypeGenerics, WhereClause,
 };
 
 use super::serde;
-use crate::{util, DeriveTrait, Trait, TraitImpl, DERIVE_WHERE};
+use crate::{util, DeriveTrait, Trait, TraitImpl};
 
 /// [`TraitImpl`] for [`Serialize`](https://docs.rs/serde/latest/serde/derive.Serialize.html).
 #[derive(Eq, PartialEq)]
@@ -58,19 +58,16 @@ impl TraitImpl for Serialize {
 		_: &ImplGenerics<'_>,
 		_: &Ident,
 		_: &TypeGenerics<'_>,
-		_: &Option<Cow<'_, WhereClause>>,
+		where_clause: &Option<Cow<'_, WhereClause>>,
 		_: TokenStream,
 	) -> TokenStream {
-		let derive_where = crate_
-			.map(Cow::Borrowed)
-			.unwrap_or_else(|| Cow::Owned(util::path_from_strs(&[DERIVE_WHERE])));
-		let serde = self.crate_();
-
-		quote! {
-			#[::core::prelude::v1::derive(#serde::Serialize)]
-			#[#derive_where::derive_where_serde]
-			#full_item
-		}
+		serde::impl_item(
+			crate_,
+			&self.crate_(),
+			format_ident!("Serialize"),
+			full_item,
+			where_clause,
+		)
 	}
 }
 

tests/serde.rs

@@ -1,10 +1,12 @@
 #![cfg(feature = "serde")]
 
+use std::marker::PhantomData;
+
 use derive_where::derive_where;
 
 #[test]
 fn test() {
-	#[derive_where(Deserialize, Serialize)]
+	#[derive_where(Deserialize, Serialize; T)]
 	#[serde(crate = "serde_")]
-	struct Test<T>(T);
+	struct Test<T, U>(T, PhantomData<U>);
 }