Properly override IsEquivalentTo() API in RuntimeType (#23137)

* Properly override IsEquivalentTo() API in RuntimeType
* Add tests for API validation

5 files changed, 46 insertions, 0 deletions

diff --git a/src/System.Private.CoreLib/src/System/RtType.cs b/src/System.Private.CoreLib/src/System/RtType.cs
index 2a71d2e759..3d03771258 100644
--- a/src/System.Private.CoreLib/src/System/RtType.cs
+++ b/src/System.Private.CoreLib/src/System/RtType.cs
@@ -3225,6 +3225,25 @@ namespace System
             return false;
         }
 
+#if FEATURE_TYPEEQUIVALENCE
+        // Reflexive, symmetric, transitive.
+        public override bool IsEquivalentTo(Type other)
+        {
+            var otherRtType = other as RuntimeType;
+            if (otherRtType is null)
+            {
+                return false;
+            }
+
+            if (otherRtType == this)
+            {
+                return true;
+            }
+
+            return RuntimeTypeHandle.IsEquivalentTo(this, otherRtType);
+        }
+#endif // FEATURE_TYPEEQUIVALENCE
+
         public override Type BaseType => GetBaseType();
 
         private RuntimeType GetBaseType()
diff --git a/src/System.Private.CoreLib/src/System/RuntimeHandles.cs b/src/System.Private.CoreLib/src/System/RuntimeHandles.cs
index 1325aa831f..56694c63b8 100644
--- a/src/System.Private.CoreLib/src/System/RuntimeHandles.cs
+++ b/src/System.Private.CoreLib/src/System/RuntimeHandles.cs
@@ -615,6 +615,11 @@ namespace System
         {
             throw new PlatformNotSupportedException();
         }
+
+#if FEATURE_TYPEEQUIVALENCE
+        [MethodImplAttribute(MethodImplOptions.InternalCall)]
+        internal static extern bool IsEquivalentTo(RuntimeType rtType1, RuntimeType rtType2);
+#endif // FEATURE_TYPEEQUIVALENCE
     }
 
     // This type is used to remove the expense of having a managed reference object that is dynamically 
diff --git a/src/vm/ecalllist.h b/src/vm/ecalllist.h
index 35fbae2160..0298939dbf 100644
--- a/src/vm/ecalllist.h
+++ b/src/vm/ecalllist.h
@@ -268,6 +268,7 @@ FCFuncStart(gCOMTypeHandleFuncs)
     FCFuncElement("Allocate", RuntimeTypeHandle::Allocate) //for A.CI
     FCFuncElement("CompareCanonicalHandles", RuntimeTypeHandle::CompareCanonicalHandles)
     FCIntrinsic("GetValueInternal", RuntimeTypeHandle::GetValueInternal, CORINFO_INTRINSIC_RTH_GetValueInternal)
+    FCFuncElement("IsEquivalentTo", RuntimeTypeHandle::IsEquivalentTo)
 FCFuncEnd()
 
 FCFuncStart(gMetaDataImport)
diff --git a/src/vm/runtimehandles.cpp b/src/vm/runtimehandles.cpp
index dda5d1d139..c8782db7ef 100644
--- a/src/vm/runtimehandles.cpp
+++ b/src/vm/runtimehandles.cpp
@@ -250,6 +250,25 @@ FCIMPL1_V(EnregisteredTypeHandle, RuntimeTypeHandle::GetValueInternal, FCALLRunt
 }
 FCIMPLEND
 
+FCIMPL2(FC_BOOL_RET, RuntimeTypeHandle::IsEquivalentTo, ReflectClassBaseObject *rtType1UNSAFE, ReflectClassBaseObject *rtType2UNSAFE)
+{
+    FCALL_CONTRACT;
+
+    REFLECTCLASSBASEREF rtType1 = (REFLECTCLASSBASEREF)ObjectToOBJECTREF(rtType1UNSAFE);
+    REFLECTCLASSBASEREF rtType2 = (REFLECTCLASSBASEREF)ObjectToOBJECTREF(rtType2UNSAFE);
+
+    BOOL areEquivalent = FALSE;
+    HELPER_METHOD_FRAME_BEGIN_RET_2(rtType1, rtType2);
+
+    if (rtType1 != NULL && rtType2 != NULL)
+        areEquivalent = rtType1->GetType().IsEquivalentTo(rtType2->GetType());
+
+    HELPER_METHOD_FRAME_END();
+
+    FC_RETURN_BOOL(areEquivalent);
+}
+FCIMPLEND
+
 // TypeEqualsHelper and TypeNotEqualsHelper are almost identical.
 // Unfortunately we cannot combime them because they need to hardcode the caller's name
 NOINLINE static BOOL TypeEqualSlow(OBJECTREF refL, OBJECTREF refR, LPVOID __me)
diff --git a/src/vm/runtimehandles.h b/src/vm/runtimehandles.h
index 6edf61ec99..66a27f4626 100644
--- a/src/vm/runtimehandles.h
+++ b/src/vm/runtimehandles.h
@@ -152,6 +152,8 @@ public:
     static FCDECL1_V(ReflectClassBaseObject*, GetTypeFromHandle, FCALLRuntimeTypeHandle th);
     static FCDECL1_V(EnregisteredTypeHandle, GetValueInternal, FCALLRuntimeTypeHandle RTH);
 
+    static FCDECL2(FC_BOOL_RET, IsEquivalentTo, ReflectClassBaseObject *rtType1UNSAFE, ReflectClassBaseObject *rtType2UNSAFE);
+
     static FCDECL2(FC_BOOL_RET, TypeEQ, Object* left, Object* right);
     static FCDECL2(FC_BOOL_RET, TypeNEQ, Object* left, Object* right);