Keep native order of get members call from Type

src/coreclr/System.Private.CoreLib/src/System/RuntimeType.CoreCLR.cs

@@ -467,7 +467,7 @@ internal void Insert(ref T[] list, string? name, MemberListType listType)
                             case MemberListType.All:
                                 if (!m_cacheComplete)
                                 {
-                                    MergeWithGlobalList(list);
+                                    MergeWithGlobalListInOrder(list);
 
                                     // Trim null entries at the end of m_allMembers array
                                     int memberCount = m_allMembers!.Length;
@@ -499,6 +499,36 @@ internal void Insert(ref T[] list, string? name, MemberListType listType)
                     }
                 }
 
+                private void MergeWithGlobalListInOrder(T[] list)
+                {
+                    T?[]? cachedMembers = m_allMembers;
+
+                    if (cachedMembers == null)
+                    {
+                        m_allMembers = list;
+                        return;
+                    }
+
+                    foreach (T? cachedMemberInfo in cachedMembers)
+                    {
+                        if (cachedMemberInfo == null)
+                            break;
+
+                        for (int i = 0; i < list.Length; i++)
+                        {
+                            T newMemberInfo = list[i];
+
+                            if (newMemberInfo.CacheEquals(cachedMemberInfo))
+                            {
+                                list[i] = cachedMemberInfo;
+                                break;
+                            }
+                        }
+                    }
+
+                    m_allMembers = list;
+                }
+
                 // Modifies the existing list.
                 private void MergeWithGlobalList(T[] list)
                 {

src/coreclr/vm/class.cpp

@@ -2702,8 +2702,22 @@ void EEClass::AddChunk (MethodDescChunk* pNewChunk)
     STATIC_CONTRACT_FORBID_FAULT;
 
     _ASSERTE(pNewChunk->GetNextChunk() == NULL);
-    pNewChunk->SetNextChunk(GetChunks());
-    SetChunks(pNewChunk);
+
+    MethodDescChunk* head = GetChunks();
+
+    if (head == NULL)
+    {
+        SetChunks(pNewChunk);
+    }
+    else
+    {
+        // Current chunk needs to be added to the end of the list so that
+        // when reflection is iterating all methods, they would come in declared order
+        while (head->GetNextChunk() != NULL)
+            head = head->GetNextChunk();
+
+        head->SetNextChunk(pNewChunk);
+    }
 }
 
 //*******************************************************************************

src/libraries/System.Runtime/tests/System.Runtime.Tests.csproj

@@ -115,6 +115,7 @@
     <Compile Include="System\RangeTests.cs" />
     <Compile Include="System\RankExceptionTests.cs" />
     <Compile Include="System\Reflection\NullabilityInfoContextTests.cs" />
+    <Compile Include="System\Reflection\RuntimeTypeMemberCacheTests.cs" />
     <Compile Include="System\SByteTests.cs" />
     <Compile Include="System\SingleTests.cs" />
     <Compile Include="System\StackOverflowExceptionTests.cs" />