[mono] When creating an array type, don't do full initialization of the element type

src/mono/mono/metadata/class-init.c

@@ -1183,8 +1183,10 @@ mono_class_create_bounded_array (MonoClass *eclass, guint32 rank, gboolean bound
 
 	mono_class_setup_supertypes (klass);
 
-	if (mono_class_is_ginst (eclass))
-		mono_class_init_internal (eclass);
+	// NOTE: this is probably too aggressive if eclass is not a valuetype.  It looks like we
+	// only need the size info in order to set MonoClass:has_references for this array type -
+	// and for that we only need to setup the fields of the element type if it's not a reference
+	// type.
 	if (!eclass->size_inited)
 		mono_class_setup_fields (eclass);
 	mono_class_set_type_load_failure_causedby_class (klass, eclass, "Could not load array element type");

src/tests/Loader/classloader/regressions/GitHub_85821/GitHub_85821.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="repro.cs" />
+  </ItemGroup>
+</Project>

src/tests/Loader/classloader/regressions/GitHub_85821/repro.cs

@@ -0,0 +1,53 @@
+using System;
+
+/* Regression test for https://github.com/dotnet/runtime/issues/85821
+ * ensure that self-referencing generic instances are initialized correctly and don't TLE
+ */
+
+public class Program
+{
+    public static int Main()
+    {
+        var test = typeof(Node<double>);
+        var fit = test.GetField("Children").FieldType;
+        if (fit == null)
+            return 101;
+
+        var test2 = typeof(Node2<int>);
+        var fit2 = test2.GetField("Children").FieldType;
+        if (fit2 == null)
+            return 102;
+
+        var test3 = typeof(NodeVT<double>);
+        var fit3 = test3.GetField("Children").FieldType;
+        if (fit3 == null)
+            return 103;
+
+        var test4 = typeof(NodeVT2<int>);
+        var fit4 = test4.GetField("Children").FieldType;
+        if (fit4 == null)
+            return 104;
+
+        return 100;
+    }
+}
+
+public class Node<T>
+{
+    public Node<T>[] Children;
+}
+
+public class Node2<T>
+{
+    public Node2<T>[][] Children;
+}
+
+public struct NodeVT<T>
+{
+    public NodeVT<T>[] Children;
+}
+
+public struct NodeVT2<T>
+{
+    public NodeVT2<T>[][] Children;
+}