Allow all selectors after unknown pseudo elements

#495

Author: devongovett

selectors/parser.rs

@@ -44,6 +44,10 @@ pub trait PseudoElement<'i>: Sized + ToCss {
   fn is_view_transition(&self) -> bool {
     false
   }
+
+  fn is_unknown(&self) -> bool {
+    false
+  }
 }
 
 /// A trait that represents a pseudo-class.
@@ -2600,7 +2604,10 @@ where
         builder.push_simple_selector(Component::Slotted(selector));
       }
       SimpleSelectorParseResult::PseudoElement(p) => {
+        if !p.is_unknown() {
         state.insert(SelectorParsingState::AFTER_PSEUDO_ELEMENT);
+          builder.push_combinator(Combinator::PseudoElement);
+        }
         if !p.accepts_state_pseudo_classes() {
           state.insert(SelectorParsingState::AFTER_NON_STATEFUL_PSEUDO_ELEMENT);
         }
@@ -2610,7 +2617,6 @@ where
         if p.is_view_transition() {
           state.insert(SelectorParsingState::AFTER_VIEW_TRANSITION);
         }
-        builder.push_combinator(Combinator::PseudoElement);
         builder.push_simple_selector(Component::PseudoElement(p));
       }
     }

src/lib.rs

@@ -6668,6 +6668,19 @@ mod tests {
         ParserError::SelectorError(SelectorError::InvalidState),
       );
     }
+
+    minify_test(".foo ::deep .bar {width: 20px}", ".foo ::deep .bar{width:20px}");
+    minify_test(".foo::deep .bar {width: 20px}", ".foo::deep .bar{width:20px}");
+    minify_test(".foo ::deep.bar {width: 20px}", ".foo ::deep.bar{width:20px}");
+    minify_test(".foo ::unknown .bar {width: 20px}", ".foo ::unknown .bar{width:20px}");
+    minify_test(
+      ".foo ::unknown(foo) .bar {width: 20px}",
+      ".foo ::unknown(foo) .bar{width:20px}",
+    );
+    minify_test(
+      ".foo ::unknown:only-child {width: 20px}",
+      ".foo ::unknown:only-child{width:20px}",
+    );
   }
 
   #[test]

src/selector.rs

@@ -1131,6 +1131,13 @@ impl<'i> parcel_selectors::parser::PseudoElement<'i> for PseudoElement<'i> {
         | PseudoElement::ViewTransitionOld { .. }
     )
   }
+
+  fn is_unknown(&self) -> bool {
+    matches!(
+      *self,
+      PseudoElement::Custom { .. } | PseudoElement::CustomFunction { .. },
+    )
+  }
 }
 
 impl<'i> PseudoElement<'i> {