From a24af35ca1b17c648880f78e28f616caac59c918 Mon Sep 17 00:00:00 2001
From: Shannon Booth <shannon@serenityos.org>
Date: Tue, 19 May 2026 21:23:04 +0200
Subject: [PATCH] LibGC: Default-construct RootHashMap from the global heap

---
 Libraries/LibGC/RootHashMap.cpp                       |  5 +++++
 Libraries/LibGC/RootHashMap.h                         |  5 +++--
 .../CSS/Invalidation/HasMutationInvalidator.cpp       |  2 +-
 .../LibJSGCTests/root_container_non_gc_type.cpp       |  2 +-
 Tests/LibGC/TestGCContainers.cpp                      | 11 +++++------
 5 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/Libraries/LibGC/RootHashMap.cpp b/Libraries/LibGC/RootHashMap.cpp
index 439d7e108b..dc47844300 100644
--- a/Libraries/LibGC/RootHashMap.cpp
+++ b/Libraries/LibGC/RootHashMap.cpp
@@ -9,6 +9,11 @@
 
 namespace GC {
 
+RootHashMapBase::RootHashMapBase()
+    : RootHashMapBase(Heap::the())
+{
+}
+
 RootHashMapBase::RootHashMapBase(Heap& heap)
     : m_heap(&heap)
 {
diff --git a/Libraries/LibGC/RootHashMap.h b/Libraries/LibGC/RootHashMap.h
index 20a86a3ee3..2dcb8feb7d 100644
--- a/Libraries/LibGC/RootHashMap.h
+++ b/Libraries/LibGC/RootHashMap.h
@@ -19,6 +19,7 @@ public:
     virtual void gather_roots(HashMap<Cell*, GC::HeapRoot>&) const = 0;
 
 protected:
+    RootHashMapBase();
     explicit RootHashMapBase(Heap&);
     ~RootHashMapBase();
 
@@ -39,8 +40,8 @@ class RootHashMap final
     using HashMapBase = HashMap<K, V, KeyTraits, ValueTraits, IsOrdered>;
 
 public:
-    explicit RootHashMap(Heap& heap)
-        : RootHashMapBase(heap)
+    RootHashMap()
+        : RootHashMapBase()
     {
     }
 
diff --git a/Libraries/LibWeb/CSS/Invalidation/HasMutationInvalidator.cpp b/Libraries/LibWeb/CSS/Invalidation/HasMutationInvalidator.cpp
index ce32bb2028..799b3a7385 100644
--- a/Libraries/LibWeb/CSS/Invalidation/HasMutationInvalidator.cpp
+++ b/Libraries/LibWeb/CSS/Invalidation/HasMutationInvalidator.cpp
@@ -338,7 +338,7 @@ static void invalidate_style_of_elements_affected_by_pending_has_mutations(Style
     ++counters.has_ancestor_walk_invocations;
 
     GC::RootHashTable<GC::Ref<DOM::Element>> elements_already_invalidated_for_has;
-    GC::OrderedRootHashMap<GC::Ref<DOM::Node>, PendingHasInvalidationMutationFeatures> pending_has_invalidations { style_scope.node().heap() };
+    GC::OrderedRootHashMap<GC::Ref<DOM::Node>, PendingHasInvalidationMutationFeatures> pending_has_invalidations;
     for (auto& [node, features] : style_scope.m_pending_has_invalidations)
         pending_has_invalidations.set(node, features);
     bool should_scan_ancestor_siblings = style_scope.have_has_selectors_with_relative_selector_that_has_sibling_combinator();
diff --git a/Tests/ClangPlugins/LibJSGCTests/root_container_non_gc_type.cpp b/Tests/ClangPlugins/LibJSGCTests/root_container_non_gc_type.cpp
index e9656faf45..e1a054d2c3 100644
--- a/Tests/ClangPlugins/LibJSGCTests/root_container_non_gc_type.cpp
+++ b/Tests/ClangPlugins/LibJSGCTests/root_container_non_gc_type.cpp
@@ -23,7 +23,7 @@ void test_root_hash_map_non_gc_types(GC::Heap& heap)
 {
     // expected-error@*{{RootHashMap requires at least one of key or value types to be convertible to Cell const* or derive from NanBoxedValue}}
     // expected-note@+1 {{in instantiation of member function}}
-    GC::RootHashMap<int, int> bad_map(heap);
+    GC::RootHashMap<int, int> bad_map;
 }
 
 // RootHashTable with a non-GC element type should fail.
diff --git a/Tests/LibGC/TestGCContainers.cpp b/Tests/LibGC/TestGCContainers.cpp
index d3ac905108..beca403aee 100644
--- a/Tests/LibGC/TestGCContainers.cpp
+++ b/Tests/LibGC/TestGCContainers.cpp
@@ -90,7 +90,7 @@ TEST_CASE(root_vector_ptr_reports_roots)
 TEST_CASE(root_hash_map_value_reports_roots)
 {
     auto& heap = test_heap();
-    GC::RootHashMap<int, GC::Ref<TestCell>> map(heap);
+    GC::RootHashMap<int, GC::Ref<TestCell>> map;
 
     auto cell = heap.allocate<TestCell>();
     map.set(42, cell);
@@ -105,7 +105,7 @@ TEST_CASE(root_hash_map_value_reports_roots)
 TEST_CASE(root_hash_map_key_reports_roots)
 {
     auto& heap = test_heap();
-    GC::RootHashMap<GC::Ref<TestCell>, int> map(heap);
+    GC::RootHashMap<GC::Ref<TestCell>, int> map;
 
     auto cell = heap.allocate<TestCell>();
     map.set(cell, 42);
@@ -120,7 +120,7 @@ TEST_CASE(root_hash_map_key_reports_roots)
 TEST_CASE(root_hash_map_key_and_value_reports_roots)
 {
     auto& heap = test_heap();
-    GC::RootHashMap<GC::Ref<TestCell>, GC::Ref<TestCell>> map(heap);
+    GC::RootHashMap<GC::Ref<TestCell>, GC::Ref<TestCell>> map;
 
     auto key_cell = heap.allocate<TestCell>();
     auto value_cell = heap.allocate<TestCell>();
@@ -137,7 +137,7 @@ TEST_CASE(root_hash_map_key_and_value_reports_roots)
 TEST_CASE(root_hash_map_non_gc_key_skipped)
 {
     auto& heap = test_heap();
-    GC::RootHashMap<int, GC::Ref<TestCell>> map(heap);
+    GC::RootHashMap<int, GC::Ref<TestCell>> map;
 
     auto cell = heap.allocate<TestCell>();
     map.set(42, cell);
@@ -243,10 +243,9 @@ TEST_CASE(root_hash_table_reports_roots)
 
 TEST_CASE(empty_containers_report_no_roots)
 {
-    auto& heap = test_heap();
     GC::RootVector<GC::Ref<TestCell>> vector;
     GC::RootHashTable<GC::Ref<TestCell>> table;
-    GC::RootHashMap<int, GC::Ref<TestCell>> map(heap);
+    GC::RootHashMap<int, GC::Ref<TestCell>> map;
 
     HashMap<GC::Cell*, GC::HeapRoot> roots;
     vector.gather_roots(roots);