Expose RuntimeFeature.IsDynamicCodeSupported/Compiled (#33928)

Fixes #29258

src/System.Runtime/ref/System.Runtime.cs

@@ -128,7 +128,6 @@ public void End() { }
         [System.CLSCompliantAttribute(false)]
         public System.TypedReference GetNextArg(System.RuntimeTypeHandle rth) { throw null; }
         public System.RuntimeTypeHandle GetNextArgType() { throw null; }
-        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.InternalCall)]
         public int GetRemainingCount() { throw null; }
     }
     public partial class ArgumentException : System.SystemException
@@ -6756,6 +6755,8 @@ public static partial class RuntimeFeature
         public const string DefaultImplementationsOfInterfaces = "DefaultImplementationsOfInterfaces";
 #endif
         public const string PortablePdb = "PortablePdb";
+        public static bool IsDynamicCodeCompiled { get { throw null; } }
+        public static bool IsDynamicCodeSupported { get { throw null; } }
         public static bool IsSupported(string feature) { throw null; }
     }
     public static partial class RuntimeHelpers

src/System.Runtime/src/ApiCompatBaseline.netcoreappaot.txt

@@ -1,14 +1,4 @@
-Compat issues with assembly System.Runtime:
 MembersMustExist : Member 'System.String System.Runtime.CompilerServices.RuntimeFeature.DefaultImplementationsOfInterfaces' does not exist in the implementation but it does exist in the contract.
-TypeCannotChangeClassification : Type 'System.DateTimeOffset' is marked as readonly in the contract so it must also be marked readonly in the implementation.
-TypeCannotChangeClassification : Type 'System.TimeSpan' is marked as readonly in the contract so it must also be marked readonly in the implementation.
-TypeCannotChangeClassification : Type 'System.Runtime.Serialization.SerializationEntry' is marked as readonly in the contract so it must also be marked readonly in the implementation.
 TypesMustExist : Type 'System.ArgIterator' does not exist in the implementation but it does exist in the contract.
-TypesMustExist : Type 'System.Index' does not exist in the implementation but it does exist in the contract. 
-TypesMustExist : Type 'System.Range' does not exist in the implementation but it does exist in the contract.
-TypesMustExist : Type 'System.Text.Rune' does not exist in the implementation but it does exist in the contract.
-TypesMustExist : Type 'System.Text.StringRuneEnumerator' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'System.ReadOnlySpan<T>.Item.get(System.Index)' does not exist in the implementation but it does exist in the contract. 
-MembersMustExist : Member 'System.ReadOnlySpan<T>.Item.get(System.Range)' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'System.Span<T>.Item.get(System.Index)' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'System.Span<T>.Item.get(System.Range)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeCompiled.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeSupported.get()' does not exist in the implementation but it does exist in the contract.

src/System.Runtime/src/ApiCompatBaseline.uapaot.txt

@@ -1,9 +1,3 @@
 TypesMustExist : Type 'System.ArgIterator' does not exist in the implementation but it does exist in the contract.
-TypesMustExist : Type 'System.Index' does not exist in the implementation but it does exist in the contract. 
-TypesMustExist : Type 'System.Range' does not exist in the implementation but it does exist in the contract.
-TypesMustExist : Type 'System.Text.Rune' does not exist in the implementation but it does exist in the contract.
-TypesMustExist : Type 'System.Text.StringRuneEnumerator' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'System.ReadOnlySpan<T>.Item.get(System.Index)' does not exist in the implementation but it does exist in the contract. 
-MembersMustExist : Member 'System.ReadOnlySpan<T>.Item.get(System.Range)' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'System.Span<T>.Item.get(System.Index)' does not exist in the implementation but it does exist in the contract.
-MembersMustExist : Member 'System.Span<T>.Item.get(System.Range)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeCompiled.get()' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeSupported.get()' does not exist in the implementation but it does exist in the contract.

src/System.Runtime/tests/System/Runtime/CompilerServices/RuntimeFeatureTests.netcoreapp.cs

@@ -15,5 +15,24 @@ public static void PortablePdb()
         {
             Assert.True(RuntimeFeature.IsSupported("PortablePdb"));
         }
+
+        [Fact]
+        public static void DynamicCode()
+        {
+            Assert.Equal(RuntimeFeature.IsDynamicCodeSupported, RuntimeFeature.IsSupported("IsDynamicCodeSupported"));
+            Assert.Equal(RuntimeFeature.IsDynamicCodeCompiled, RuntimeFeature.IsSupported("IsDynamicCodeCompiled"));
+
+            if (RuntimeFeature.IsDynamicCodeCompiled)
+            {
+                Assert.True(RuntimeFeature.IsDynamicCodeSupported);
+            }
+        }
+
+        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsNotNetNative))]
+        public static void DynamicCode_Jit()
+        {
+            Assert.True(RuntimeFeature.IsDynamicCodeSupported);
+            Assert.True(RuntimeFeature.IsDynamicCodeCompiled);
+        }
     }
 }