REGRESSION (Safari 17): Named at-rule container skipped when containe…

…r named in a :host selector https://bugs.webkit.org/show_bug.cgi?id=267046 rdar://120428386 Reviewed by Alan Baradlay. * LayoutTests/imported/w3c/web-platform-tests/css/css-contain/container-queries/container-name-tree-scoped-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/css/css-contain/container-queries/container-name-tree-scoped.html: * Source/WebCore/style/ContainerQueryEvaluator.cpp: (WebCore::Style::ContainerQueryEvaluator::selectContainer): A container query should be allowed to match a host element with container name that defined by :host rule in the same shadow tree as the query. Canonical link: https://commits.webkit.org/273987@main
WebKit · Feb 2, 2024 · 14e1048 · 14e1048
1 parent 2ec06d7
commit 14e1048
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Showing 3 changed files with 29 additions and 5 deletions.
diff --git a/...-platform-tests/css/css-contain/container-queries/container-name-tree-scoped-expected.txt b/...-platform-tests/css/css-contain/container-queries/container-name-tree-scoped-expected.txt
@@ -1,4 +1,5 @@
 
 PASS Outer scope query should not match container-name set by :host rule in shadow tree
 PASS Outer scope query should not match container-name set by ::slotted rule in shadow tree
+PASS Inner scope query should match container-name set by :host rule in shadow tree
 
diff --git a/.../w3c/web-platform-tests/css/css-contain/container-queries/container-name-tree-scoped.html b/.../w3c/web-platform-tests/css/css-contain/container-queries/container-name-tree-scoped.html
@@ -52,6 +52,21 @@
       #t2 { color: red; }
     }
   </style>
+
+  <div id="container-name-host-inner-container-rule">
+    <div id="t3host">
+      <template shadowrootmode="open">
+        <style>
+          :host { container-name: foo; }
+          #t3 { color: red; }
+          @container foo (width > 0px) {
+            #t3 { color: green; }
+          }
+        </style>
+        <div id="t3"></div>
+      </template>
+    </div>
+  </div>
 </div>
 
 <script>
@@ -70,4 +85,8 @@
     assert_equals(getComputedStyle(t2).color, green);
   }, "Outer scope query should not match container-name set by ::slotted rule in shadow tree");
 
+  test(() => {
+    assert_equals(getComputedStyle(t3host.shadowRoot.querySelector('#t3')).color, green);
+  }, "Inner scope query should match container-name set by :host rule in shadow tree");
+
 </script>
diff --git a/Source/WebCore/style/ContainerQueryEvaluator.cpp b/Source/WebCore/style/ContainerQueryEvaluator.cpp
@@ -117,11 +117,15 @@ const Element* ContainerQueryEvaluator::selectContainer(OptionSet<CQ::Axis> axes
         if (name.isEmpty())
             return true;
         return style->containerNames().containsIf([&](auto& scopedName) {
-            // Names from the inner scopes are ignored.
-            // FIXME: Should names from inner scopes be allowed in some cases?
-            if (scopedName.scopeOrdinal > ScopeOrdinal::Element)
-                return false;
-            return scopedName.name == name;
+            auto isNameFromAllowedScope = [&](auto& scopedName) {
+                // Names from :host rules are allowed when the candidate is the host element.
+                auto isHost = element.shadowHost() == &candidateElement;
+                if (scopedName.scopeOrdinal == ScopeOrdinal::Shadow && isHost)
+                    return true;
+                // Otherwise names from the inner scopes are ignored.
+                return scopedName.scopeOrdinal <= ScopeOrdinal::Element;
+            };
+            return isNameFromAllowedScope(scopedName) && scopedName.name == name;
         });
     };