fix: don't render a comment node for () attributes in template (closes #4079)

tachys/src/html/class.rs

@@ -540,20 +540,11 @@ impl IntoClass for (&'static str, bool) {
     fn rebuild(self, state: &mut Self::State) {
         let (name, include) = self;
         let (class_list, prev_include, prev_name) = state;
-        if name == *prev_name {
-            if include != *prev_include {
-                if include {
-                    Rndr::add_class(class_list, name);
-                } else {
-                    Rndr::remove_class(class_list, name);
-                }
-            }
-        } else {
-            if *prev_include {
-                Rndr::remove_class(class_list, prev_name);
-            }
+        if include != *prev_include {
             if include {
                 Rndr::add_class(class_list, name);
+            } else {
+                Rndr::remove_class(class_list, name);
             }
         }
         *prev_include = include;

tachys/src/html/element/mod.rs

@@ -709,7 +709,7 @@ where
 
             buf.push('<');
             buf.push_str(E::TAG);
-            <At as ToTemplate>::to_template(
+            <At as ToTemplate>::to_template_attribute(
                 buf,
                 &mut class,
                 &mut style,

tachys/src/reactive_graph/class.rs

@@ -209,15 +209,6 @@ where
 
     fn rebuild(self, state: &mut Self::State) {
         let (name, mut f) = self;
-
-        let prev_name = state.name;
-        let prev_state = state.effect.take_value();
-        if let Some((list, prev_include)) = &prev_state {
-            if prev_name != name && *prev_include {
-                Rndr::remove_class(list, prev_name);
-            }
-        }
-
         // Name might've updated:
         state.name = name;
         let mut first_run = true;
@@ -241,7 +232,7 @@ where
                     }
                 }
             },
-            prev_state,
+            state.effect.take_value(),
         );
     }
 

tachys/src/view/mod.rs

@@ -437,6 +437,17 @@ pub trait ToTemplate {
         inner_html: &mut String,
         position: &mut Position,
     );
+
+    /// Renders a view type to a template in attribute position.
+    fn to_template_attribute(
+        buf: &mut String,
+        class: &mut String,
+        style: &mut String,
+        inner_html: &mut String,
+        position: &mut Position,
+    ) {
+        Self::to_template(buf, class, style, inner_html, position);
+    }
 }
 
 /// Keeps track of what position the item currently being hydrated is in, relative to its siblings

tachys/src/view/tuples.rs

@@ -103,6 +103,15 @@ impl ToTemplate for () {
     ) {
         buf.push_str("<!>");
     }
+
+    fn to_template_attribute(
+        _buf: &mut String,
+        _class: &mut String,
+        _style: &mut String,
+        _inner_html: &mut String,
+        _position: &mut Position,
+    ) {
+    }
 }
 
 impl<A: Render> Render for (A,) {