Simplify trait bound declarations

instant-xml-macros/src/lib.rs

@@ -136,10 +136,7 @@ pub fn to_xml(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
 
     proc_macro::TokenStream::from(quote!(
         impl #generics ToXml for #ident #generics {
-            fn serialize<W>(&self, serializer: &mut instant_xml::Serializer<W>) -> Result<(), instant_xml::Error>
+            fn serialize<W: std::fmt::Write>(&self, serializer: &mut instant_xml::Serializer<W>) -> Result<(), instant_xml::Error> {
-            where
-                W: std::fmt::Write,
-            {
                 let _ = serializer.consume_field_context();
                 let mut field_context = instant_xml::FieldContext {
                     name: #root_name,

instant-xml/src/impls.rs

@@ -63,10 +63,10 @@ where
 macro_rules! to_xml_for_number {
     ($typ:ty) => {
         impl ToXml for $typ {
-            fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
+            fn serialize<W: fmt::Write>(
-            where
+                &self,
-                W: fmt::Write,
+                serializer: &mut Serializer<W>,
-            {
+            ) -> Result<(), Error> {
                 DisplayToXml(self).serialize(serializer)
             }
         }
@@ -87,10 +87,7 @@ to_xml_for_number!(f32);
 to_xml_for_number!(f64);
 
 impl ToXml for bool {
-    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
+    fn serialize<W: fmt::Write>(&self, serializer: &mut Serializer<W>) -> Result<(), Error> {
-    where
-        W: fmt::Write,
-    {
         let value = match self {
             true => "true",
             false => "false",
@@ -101,50 +98,32 @@ impl ToXml for bool {
 }
 
 impl ToXml for String {
-    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
+    fn serialize<W: fmt::Write>(&self, serializer: &mut Serializer<W>) -> Result<(), Error> {
-    where
-        W: fmt::Write,
-    {
         DisplayToXml(&escape(self)?).serialize(serializer)
     }
 }
 
 impl ToXml for char {
-    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
+    fn serialize<W: fmt::Write>(&self, serializer: &mut Serializer<W>) -> Result<(), Error> {
-    where
-        W: fmt::Write,
-    {
         let mut tmp = [0u8; 4];
         DisplayToXml(&escape(&*self.encode_utf8(&mut tmp))?).serialize(serializer)
     }
 }
 
 impl ToXml for &str {
-    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
+    fn serialize<W: fmt::Write>(&self, serializer: &mut Serializer<W>) -> Result<(), Error> {
-    where
-        W: fmt::Write,
-    {
         DisplayToXml(&escape(self)?).serialize(serializer)
     }
 }
 
 impl ToXml for Cow<'_, str> {
-    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
+    fn serialize<W: fmt::Write>(&self, serializer: &mut Serializer<W>) -> Result<(), Error> {
-    where
-        W: fmt::Write,
-    {
         DisplayToXml(&escape(self)?).serialize(serializer)
     }
 }
 
-impl<T> ToXml for Option<T>
+impl<T: ToXml> ToXml for Option<T> {
-where
+    fn serialize<W: fmt::Write>(&self, serializer: &mut Serializer<W>) -> Result<(), Error> {
-    T: ToXml,
-{
-    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
-    where
-        W: fmt::Write,
-    {
         match self {
             Some(v) => v.serialize(serializer),
             None => Ok(()),

instant-xml/src/lib.rs

@@ -34,15 +34,10 @@ pub trait ToXml {
         Ok(output)
     }
 
-    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
+    fn serialize<W: fmt::Write>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>;
-    where
-        W: fmt::Write;
 }
 
-pub struct Serializer<'xml, W>
+pub struct Serializer<'xml, W: fmt::Write> {
-where
-    W: fmt::Write,
-{
     // For parent namespaces the key is the namespace and the value is the prefix. We are adding to map
     // only if the namespaces do not exist, if it does exist then we are using an already defined parent prefix.
     #[doc(hidden)]
@@ -56,7 +51,7 @@ where
     next_field_context: Option<FieldContext<'xml>>,
 }
 
-impl<'xml, W: std::fmt::Write> Serializer<'xml, W> {
+impl<'xml, W: fmt::Write> Serializer<'xml, W> {
     pub fn new(output: &'xml mut W) -> Self {
         Self {
             parent_namespaces: HashMap::new(),
@@ -74,20 +69,14 @@ impl<'xml, W: std::fmt::Write> Serializer<'xml, W> {
         Ok(())
     }
 
-    pub fn add_attribute_key<T>(&mut self, attr_key: &T) -> Result<(), Error>
+    pub fn add_attribute_key(&mut self, attr_key: &impl fmt::Display) -> Result<(), Error> {
-    where
-        T: fmt::Display,
-    {
         self.current_attributes.push(' ');
         write!(self.current_attributes, "{}", attr_key)?;
         self.current_attributes.push('=');
         Ok(())
     }
 
-    pub fn add_attribute_value<T>(&mut self, attr_value: &T) -> Result<(), Error>
+    pub fn add_attribute_value(&mut self, attr_value: &impl fmt::Display) -> Result<(), Error> {
-    where
-        T: fmt::Display,
-    {
         self.current_attributes.push('"');
         write!(self.current_attributes, "{}", attr_value)?;
         self.current_attributes.push('"');