REGRESSION(264248@main): A floating element can cause a list item's b…

…ullet to be orphaned on overconstrained lines

https://bugs.webkit.org/show_bug.cgi?id=266801
<rdar://problem/120022893>

Reviewed by Antti Koivisto.

Do not disconnect list marker and the associated list item when they are embedded in a list element (e.g. <div><ul><li> vs. <div><li>) -and they are not positioned inside.
This quirky behavior matches both Chrome and legacy line layout.

* LayoutTests/fast/inline/list-item-inside-list-and-wrap-expected.html: Added.
* LayoutTests/fast/inline/list-item-inside-list-and-wrap.html: Added.
* Source/WebCore/layout/formattingContexts/inline/InlineFormattingUtils.cpp:
(WebCore::Layout::isAtSoftWrapOpportunity): Check whether we are inside a list element to decide whether we can break after the list marker.
* Source/WebCore/layout/integration/LayoutIntegrationBoxTree.cpp:
(WebCore::LayoutIntegration::BoxTree::createLayoutBox):
* Source/WebCore/layout/layouttree/LayoutElementBox.h:
(WebCore::Layout::ElementBox::isListMarkerInsideList const):

Canonical link: https://commits.webkit.org/272451@main

LayoutTests/fast/inline/list-item-inside-list-and-wrap-expected.html

@@ -0,0 +1,20 @@
+<style>
+.container {
+  width: 400px;
+  font-family: Monospace;
+}
+.float_box {
+  float: left;
+  width: 400px;
+  height: 20px;
+}
+</style>
+<div class=container>
+  <ul style="margin-top: 28px;">
+      <li>Pass if bullet appears in front of item</li>
+  </ul>
+<div class=container>
+  <div class=float_box style="width: 380px"></div>
+      <li><br>Pass if item wraps</li>
+</div>
+</div>

LayoutTests/fast/inline/list-item-inside-list-and-wrap.html

@@ -0,0 +1,22 @@
+<style>
+.container {
+  width: 400px;
+  font-family: Monospace;
+}
+
+.float_box {
+  float: left;
+  width: 400px;
+  height: 20px;
+}
+</style>
+<div class=container>
+  <div class=float_box></div>
+  <ul>
+      <li>Pass if bullet appears in front of item</li>
+  </ul>
+</div>
+<div class=container>
+  <div class=float_box style="width: 380px"></div>
+      <li>Pass if item wraps</li>
+</div>

Source/WebCore/layout/formattingContexts/inline/InlineFormattingUtils.cpp

@@ -404,8 +404,14 @@ static inline bool isAtSoftWrapOpportunity(const InlineItem& previous, const Inl
         // [text-][text] : after [hyphen] position is a soft wrap opportunity.
         return endsWithSoftWrapOpportunity(currentInlineTextItem, nextInlineTextItem);
     }
-    if (previous.layoutBox().isListMarkerBox() || next.layoutBox().isListMarkerBox())
+    if (previous.layoutBox().isListMarkerBox()) {
+        auto& listMarkerBox = downcast<ElementBox>(previous.layoutBox());
+        return !listMarkerBox.isListMarkerInsideList() || !listMarkerBox.isListMarkerOutside();
+    }
+    if (next.layoutBox().isListMarkerBox()) {
+        // FIXME: SHould this ever be the case?
         return true;
+    }
     if (previous.isBox() || next.isBox()) {
         // [text][inline box start][inline box end][inline box] (text<span></span><img>) : there's a soft wrap opportunity between the [text] and [img].
         // The line breaking behavior of a replaced element or other atomic inline is equivalent to an ideographic character.

Source/WebCore/layout/integration/LayoutIntegrationBoxTree.cpp

@@ -231,6 +231,8 @@ UniqueRef<Layout::Box> BoxTree::createLayoutBox(RenderObject& renderer)
             listMarkerAttributes.add(Layout::ElementBox::ListMarkerAttribute::Image);
         if (!listMarkerRenderer.isInside())
             listMarkerAttributes.add(Layout::ElementBox::ListMarkerAttribute::Outside);
+        if (listMarkerRenderer.listItem() && !listMarkerRenderer.listItem()->notInList())
+            listMarkerAttributes.add(Layout::ElementBox::ListMarkerAttribute::HasListElementAncestor);
         return makeUniqueRef<Layout::ElementBox>(elementAttributes(renderElement), listMarkerAttributes, WTFMove(style), WTFMove(firstLineStyle));
     }
 

Source/WebCore/layout/layouttree/LayoutElementBox.h

@@ -41,7 +41,11 @@ class ElementBox : public Box {
 public:
     ElementBox(ElementAttributes&&, RenderStyle&&, std::unique_ptr<RenderStyle>&& firstLineStyle = nullptr, OptionSet<BaseTypeFlag> = { ElementBoxFlag });
 
-    enum class ListMarkerAttribute : uint8_t { Image = 1 << 0, Outside = 1 << 1 };
+    enum class ListMarkerAttribute : uint8_t {
+        Image = 1 << 0,
+        Outside = 1 << 1,
+        HasListElementAncestor = 1 << 2
+    };
     ElementBox(ElementAttributes&&, OptionSet<ListMarkerAttribute>, RenderStyle&&, std::unique_ptr<RenderStyle>&& firstLineStyle = nullptr);
 
     struct ReplacedAttributes {
@@ -85,6 +89,7 @@ class ElementBox : public Box {
 
     bool isListMarkerImage() const { return m_replacedData && m_replacedData->listMarkerAttributes.contains(ListMarkerAttribute::Image); }
     bool isListMarkerOutside() const { return m_replacedData && m_replacedData->listMarkerAttributes.contains(ListMarkerAttribute::Outside); }
+    bool isListMarkerInsideList() const { return m_replacedData && m_replacedData->listMarkerAttributes.contains(ListMarkerAttribute::HasListElementAncestor); }
 
     // FIXME: This doesn't belong.
     CachedImage* cachedImage() const { return m_replacedData ? m_replacedData->cachedImage : nullptr; }