xml: Move XmlRoot implementation into dedicated derive macro

crates/xml/derive/src/de/attrs.rs

@@ -24,7 +24,8 @@ pub struct VariantAttrs {
 #[darling(attributes(xml))]
 pub struct EnumAttrs {
     #[darling(flatten)]
-    container: ContainerAttrs,
+    pub container: ContainerAttrs,
+    pub untagged: Flag,
 }
 
 #[derive(Default, FromDeriveInput, Clone)]

crates/xml/derive/src/de/de_struct.rs

@@ -56,6 +56,17 @@ pub struct NamedStruct {
 }
 
 impl NamedStruct {
+    pub fn impl_xml_root(&self) -> proc_macro2::TokenStream {
+        let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
+        let ident = &self.ident;
+        let root = self.attrs.root.as_ref().expect("No root attribute found");
+        quote! {
+            impl #impl_generics ::rustical_xml::XmlRoot for #ident #type_generics #where_clause {
+                fn root_tag() -> &'static [u8] { #root }
+            }
+        }
+    }
+
     pub fn impl_de(&self) -> proc_macro2::TokenStream {
         let (impl_generics, type_generics, where_clause) = self.generics.split_for_impl();
         let ident = &self.ident;
@@ -76,21 +87,9 @@ impl NamedStruct {
 
         let builder_field_builds = self.fields.iter().map(Field::builder_field_build);
 
-        let xml_root_impl = if let Some(root) = &self.attrs.root {
-            quote! {
-                impl #impl_generics ::rustical_xml::XmlRoot for #ident #type_generics #where_clause {
-                    fn root_tag() -> &'static [u8] { #root }
-                }
-            }
-        } else {
-            quote! {}
-        };
-
         let invalid_field_branch = invalid_field_branch(self.attrs.allow_invalid.is_present());
 
         quote! {
-            #xml_root_impl
-
             impl #impl_generics ::rustical_xml::XmlDeserialize for #ident #type_generics #where_clause {
                 fn deserialize<R: BufRead>(
                     reader: &mut quick_xml::NsReader<R>,

crates/xml/derive/src/lib.rs

@@ -2,7 +2,6 @@ use core::panic;
 use syn::{parse_macro_input, DeriveInput};
 
 mod de;
-
 use de::{impl_de_enum, NamedStruct};
 
 #[proc_macro_derive(XmlDeserialize, attributes(xml))]
@@ -16,3 +15,15 @@ pub fn derive_xml_deserialize(input: proc_macro::TokenStream) -> proc_macro::Tok
     }
     .into()
 }
+
+#[proc_macro_derive(XmlRoot, attributes(xml))]
+pub fn derive_xml_root(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+
+    match &input.data {
+        syn::Data::Struct(s) => NamedStruct::parse(&input, s).impl_xml_root(),
+        syn::Data::Enum(_) => panic!("Enum not supported as root"),
+        syn::Data::Union(_) => panic!("Union not supported as root"),
+    }
+    .into()
+}

crates/xml/src/de.rs

@@ -86,4 +86,4 @@ pub trait XmlRootParseStr<'i>: XmlRoot + XmlDeserialize {
     }
 }
 
-impl<'i, T: XmlRoot + XmlDeserialize> XmlRootParseStr<'i> for T {}
+impl<T: XmlRoot + XmlDeserialize> XmlRootParseStr<'_> for T {}

crates/xml/tests/de_struct.rs

@@ -2,10 +2,11 @@ use rustical_xml::de::XmlRootParseStr;
 use rustical_xml::{Unit, Unparsed, XmlDeserialize};
 use std::collections::HashSet;
 use std::io::BufRead;
+use xml_derive::XmlRoot;
 
 #[test]
 fn test_struct_text_field() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document")]
     struct Document {
         #[xml(ty = "text")]
@@ -26,7 +27,7 @@ fn test_struct_text_field() {
 
 #[test]
 fn test_struct_document() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document")]
     struct Document {
         child: Child,
@@ -51,7 +52,7 @@ fn test_struct_document() {
 
 #[test]
 fn test_struct_rename_field() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document")]
     struct Document {
         #[xml(rename = b"ok-wow")]
@@ -77,7 +78,7 @@ fn test_struct_rename_field() {
 
 #[test]
 fn test_struct_optional_field() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document")]
     struct Document {
         #[xml(default = "Default::default")]
@@ -96,7 +97,7 @@ fn test_struct_optional_field() {
 
 #[test]
 fn test_struct_vec() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document")]
     struct Document {
         #[xml(rename = b"child", flatten)]
@@ -124,7 +125,7 @@ fn test_struct_vec() {
 
 #[test]
 fn test_struct_set() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document")]
     struct Document {
         #[xml(rename = b"child", flatten)]
@@ -152,7 +153,7 @@ fn test_struct_set() {
 
 #[test]
 fn test_struct_ns() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document", ns_strict)]
     struct Document {
         #[xml(ns = b"hello")]
@@ -165,7 +166,7 @@ fn test_struct_ns() {
 
 #[test]
 fn test_struct_attr() {
-    #[derive(Debug, XmlDeserialize, PartialEq)]
+    #[derive(Debug, XmlDeserialize, XmlRoot, PartialEq)]
     #[xml(root = b"document", ns_strict)]
     struct Document {
         #[xml(ns = b"hello")]
@@ -192,7 +193,7 @@ fn test_struct_attr() {
 
 #[test]
 fn test_struct_generics() {
-    #[derive(XmlDeserialize)]
+    #[derive(XmlDeserialize, XmlRoot)]
     #[xml(root = b"document", ns_strict)]
     struct Document<T: XmlDeserialize> {
         child: T,
@@ -212,7 +213,7 @@ fn test_struct_generics() {
 
 #[test]
 fn test_struct_unparsed() {
-    #[derive(XmlDeserialize)]
+    #[derive(XmlDeserialize, XmlRoot)]
     #[xml(root = b"document", ns_strict)]
     struct Document {
         child: Unparsed,