Add RuntimeFeature detection for default interface method (#11940)

1 files changed, 6 insertions, 4 deletions

diff --git a/src/mscorlib/shared/System/Runtime/CompilerServices/RuntimeFeature.cs b/src/mscorlib/shared/System/Runtime/CompilerServices/RuntimeFeature.cs
index 090acff559..4978b09b72 100644
--- a/src/mscorlib/shared/System/Runtime/CompilerServices/RuntimeFeature.cs
+++ b/src/mscorlib/shared/System/Runtime/CompilerServices/RuntimeFeature.cs
@@ -11,17 +11,19 @@ namespace System.Runtime.CompilerServices
         /// </summary>
         public const string PortablePdb = nameof(PortablePdb);
 
+        /// Indicates that this version of runtime supports default interface method implementations.
+        /// </summary>
+        public const string DefaultImplementationsOfInterfaces = nameof(DefaultImplementationsOfInterfaces);
+
         /// <summary>
         /// Checks whether a certain feature is supported by the Runtime.
         /// </summary>
         public static bool IsSupported(string feature)
         {
-            // Features should be added as public const string fields in the same class.
-            // Example: public const string FeatureName = nameof(FeatureName);
-
             switch (feature)
             {
-                case nameof(PortablePdb):
+                case PortablePdb:
+                case DefaultImplementationsOfInterfaces:
                     return true;
             }