From bfa493eef451adcf185787ffc7ac754adc330d20 Mon Sep 17 00:00:00 2001
From: Sam Atkins <sam@ladybird.org>
Date: Wed, 26 Mar 2025 14:40:23 +0000
Subject: [PATCH] LibWeb/CSS: Give all style values a visit_edges() method

Having this hidden away in ImageStyleValue meant that
CSSStyleProperties (and anyone else who holds style values) had to know
exactly which types need visiting. This is a footgun waiting to happen,
so make this a virtual method on CSSStyleValue instead.
---
 Libraries/LibWeb/CSS/CSSStyleProperties.cpp          | 3 +--
 Libraries/LibWeb/CSS/CSSStyleValue.h                 | 3 +++
 Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.cpp | 1 +
 Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.h   | 5 ++++-
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/Libraries/LibWeb/CSS/CSSStyleProperties.cpp b/Libraries/LibWeb/CSS/CSSStyleProperties.cpp
index 93f6a1dee41..1ac05042e8b 100644
--- a/Libraries/LibWeb/CSS/CSSStyleProperties.cpp
+++ b/Libraries/LibWeb/CSS/CSSStyleProperties.cpp
@@ -85,8 +85,7 @@ void CSSStyleProperties::visit_edges(Visitor& visitor)
 {
     Base::visit_edges(visitor);
     for (auto& property : m_properties) {
-        if (property.value->is_image())
-            property.value->as_image().visit_edges(visitor);
+        property.value->visit_edges(visitor);
     }
 }
 
diff --git a/Libraries/LibWeb/CSS/CSSStyleValue.h b/Libraries/LibWeb/CSS/CSSStyleValue.h
index 14f39ad61ac..73e5e00b84c 100644
--- a/Libraries/LibWeb/CSS/CSSStyleValue.h
+++ b/Libraries/LibWeb/CSS/CSSStyleValue.h
@@ -18,6 +18,7 @@
 #include <AK/Vector.h>
 #include <AK/WeakPtr.h>
 #include <LibGfx/Color.h>
+#include <LibJS/Heap/Cell.h>
 #include <LibURL/URL.h>
 #include <LibWeb/CSS/Keyword.h>
 #include <LibWeb/CSS/Length.h>
@@ -369,6 +370,8 @@ public:
     [[nodiscard]] int to_font_slope() const;
     [[nodiscard]] int to_font_width() const;
 
+    virtual void visit_edges(JS::Cell::Visitor&) const { }
+
     virtual bool equals(CSSStyleValue const& other) const = 0;
 
     bool operator==(CSSStyleValue const& other) const
diff --git a/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.cpp b/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.cpp
index df73bc93737..c35ddf8fcde 100644
--- a/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.cpp
+++ b/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.cpp
@@ -30,6 +30,7 @@ ImageStyleValue::~ImageStyleValue() = default;
 
 void ImageStyleValue::visit_edges(JS::Cell::Visitor& visitor) const
 {
+    Base::visit_edges(visitor);
     // FIXME: visit_edges in non-GC allocated classes is confusing pattern.
     //        Consider making CSSStyleValue to be GC allocated instead.
     visitor.visit(m_resource_request);
diff --git a/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.h b/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.h
index 878c900c402..d643635efe0 100644
--- a/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.h
+++ b/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.h
@@ -21,6 +21,9 @@ namespace Web::CSS {
 class ImageStyleValue final
     : public AbstractImageStyleValue
     , public Weakable<ImageStyleValue> {
+
+    using Base = AbstractImageStyleValue;
+
 public:
     static ValueComparingNonnullRefPtr<ImageStyleValue> create(URL::URL const& url)
     {
@@ -28,7 +31,7 @@ public:
     }
     virtual ~ImageStyleValue() override;
 
-    void visit_edges(JS::Cell::Visitor& visitor) const;
+    virtual void visit_edges(JS::Cell::Visitor& visitor) const override;
 
     virtual String to_string(SerializationMode) const override;
     virtual bool equals(CSSStyleValue const& other) const override;