Fix nth of selectors in css modules

Fixes #883

selectors/parser.rs

@@ -1302,7 +1302,7 @@ impl NthSelectorData {
 
   /// Writes the beginning of the selector.
   #[inline]
-  fn write_start<W: fmt::Write>(&self, dest: &mut W, is_function: bool) -> fmt::Result {
+  pub fn write_start<W: fmt::Write>(&self, dest: &mut W, is_function: bool) -> fmt::Result {
     dest.write_str(match self.ty {
       NthType::Child if is_function => ":nth-child(",
       NthType::Child => ":first-child",
@@ -1322,7 +1322,7 @@ impl NthSelectorData {
   /// Serialize <an+b> (part of the CSS Syntax spec, but currently only used here).
   /// <https://drafts.csswg.org/css-syntax-3/#serialize-an-anb-value>
   #[inline]
-  fn write_affine<W: fmt::Write>(&self, dest: &mut W) -> fmt::Result {
+  pub fn write_affine<W: fmt::Write>(&self, dest: &mut W) -> fmt::Result {
     match (self.a, self.b) {
       (0, 0) => dest.write_char('0'),
 

src/lib.rs

@@ -24993,6 +24993,27 @@ mod tests {
         Default::default(),
         true,
       );
+
+      css_modules_test(
+        ":nth-child(1 of .foo) {width: 20px}",
+        ":nth-child(1 of .EgL3uq_foo){width:20px}",
+        map! {
+          "foo" => "EgL3uq_foo"
+        },
+        HashMap::new(),
+        Default::default(),
+        true,
+      );
+      css_modules_test(
+        ":nth-last-child(1 of .foo) {width: 20px}",
+        ":nth-last-child(1 of .EgL3uq_foo){width:20px}",
+        map! {
+          "foo" => "EgL3uq_foo"
+        },
+        HashMap::new(),
+        Default::default(),
+        true,
+      );
     }
 
     // Stable hashes between project roots.

src/selector.rs

@@ -1622,6 +1622,14 @@ where
       selector.to_css(dest)?;
       dest.write_char(')')
     }
+    Component::NthOf(ref nth_of_data) => {
+      let nth_data = nth_of_data.nth_data();
+      nth_data.write_start(dest, true)?;
+      nth_data.write_affine(dest)?;
+      dest.write_str(" of ")?;
+      serialize_selector_list(nth_of_data.selectors().iter(), dest, context, true)?;
+      dest.write_char(')')
+    }
     _ => {
       cssparser::ToCss::to_css(component, dest)?;
       Ok(())