Make metadata collections no longer implement generic IReadOnlyCollection

This has a positive size on disk impact since generic IEnumerable and IEnumerator interfaces come with a bunch of costs. Low level metadata APIs don't have to be fancy. This also removes a bunch of boxing as an added bonus.

[tfs-changeset: 1666112]

2 files changed, 6 insertions, 5 deletions

diff --git a/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/IntPtrConstructorMethodInvoker.cs b/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/IntPtrConstructorMethodInvoker.cs
index 51e101e42..1cbe6ed6c 100644
--- a/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/IntPtrConstructorMethodInvoker.cs
+++ b/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/IntPtrConstructorMethodInvoker.cs
@@ -27,10 +27,12 @@ namespace Internal.Reflection.Execution.MethodInvokers
             // Since we control the definition of System.IntPtr, we only do enough analysis of the signature to disambiguate the constructors we support.
             _id = IntPtrConstructorId.None;
             Method method = methodHandle.GetMethod(reader);
-            Handle[] parameterTypeSignatureHandles = method.Signature.GetMethodSignature(reader).Parameters.ToArray();
-            if (parameterTypeSignatureHandles.Length == 1)
+            HandleCollection parameterTypeSignatureHandles = method.Signature.GetMethodSignature(reader).Parameters;
+            if (parameterTypeSignatureHandles.Count == 1)
             {
-                Handle parameterTypeHandle = parameterTypeSignatureHandles[0];
+                HandleCollection.Enumerator enumerator = parameterTypeSignatureHandles.GetEnumerator();
+                enumerator.MoveNext();
+                Handle parameterTypeHandle = enumerator.Current;
 
                 // If any parameter is a pointer type, bail as we don't support Invokes on pointers.
                 if (parameterTypeHandle.HandleType != HandleType.TypeDefinition)
diff --git a/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/NullableInstanceMethodInvoker.cs b/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/NullableInstanceMethodInvoker.cs
index be7f54a35..31d817f73 100644
--- a/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/NullableInstanceMethodInvoker.cs
+++ b/src/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/MethodInvokers/NullableInstanceMethodInvoker.cs
@@ -71,8 +71,7 @@ namespace Internal.Reflection.Execution.MethodInvokers
                         break;
 
                     case "GetValueOrDefault":
-                        IEnumerator<Handle> parameters = method.Signature.GetMethodSignature(reader).Parameters.GetEnumerator();
-                        if (parameters.MoveNext())
+                        if (method.Signature.GetMethodSignature(reader).Parameters.Count == 1)
                             _id = NullableMethodId.GetValueOrDefault_1;
                         else
                             _id = NullableMethodId.GetValueOrDefault_0;