Add missing readonly modifiers to GCHandle and DependentHandle

src/coreclr/System.Private.CoreLib/src/System/Runtime/DependentHandle.cs

@@ -71,7 +71,7 @@ public DependentHandle(object? target, object? dependent)
         /// <see cref="DependentHandle(object?, object?)"/> and has not yet been disposed.
         /// </summary>
         /// <remarks>This property is thread-safe.</remarks>
-        public bool IsAllocated => (nint)_handle != 0;
+        public readonly bool IsAllocated => (nint)_handle != 0;
 
         /// <summary>
         /// Gets or sets the target object instance for the current handle. The target can only be set to a <see langword="null"/> value
@@ -83,7 +83,7 @@ public DependentHandle(object? target, object? dependent)
         /// <remarks>This property is thread-safe.</remarks>
         public object? Target
         {
-            get
+            readonly get
             {
                 IntPtr handle = _handle;
 
@@ -120,7 +120,7 @@ public object? Target
         /// <remarks>This property is thread-safe.</remarks>
         public object? Dependent
         {
-            get
+            readonly get
             {
                 IntPtr handle = _handle;
 
@@ -154,7 +154,7 @@ public object? Dependent
         /// <returns>The values of <see cref="Target"/> and <see cref="Dependent"/>.</returns>
         /// <exception cref="InvalidOperationException">Thrown if <see cref="IsAllocated"/> is <see langword="false"/>.</exception>
         /// <remarks>This property is thread-safe.</remarks>
-        public (object? Target, object? Dependent) TargetAndDependent
+        public readonly (object? Target, object? Dependent) TargetAndDependent
         {
             get
             {
@@ -176,7 +176,7 @@ public object? Dependent
         /// </summary>
         /// <returns>The target object instance, if present.</returns>
         /// <remarks>This method mirrors <see cref="Target"/>, but without the allocation check.</remarks>
-        internal object? UnsafeGetTarget()
+        internal readonly object? UnsafeGetTarget()
         {
             return InternalGetTarget(_handle);
         }
@@ -191,7 +191,7 @@ public object? Dependent
         /// The signature is also kept the same as the one for the internal call, to improve the codegen.
         /// Note that <paramref name="dependent"/> is required to be on the stack (or it might not be tracked).
         /// </remarks>
-        internal object? UnsafeGetTargetAndDependent(out object? dependent)
+        internal readonly object? UnsafeGetTargetAndDependent(out object? dependent)
         {
             return InternalGetTargetAndDependent(_handle, out dependent);
         }
@@ -200,7 +200,7 @@ public object? Dependent
         /// Sets the dependent object instance for the current handle to <see langword="null"/>.
         /// </summary>
         /// <remarks>This method mirrors the <see cref="Target"/> setter, but without allocation and input checks.</remarks>
-        internal void UnsafeSetTargetToNull()
+        internal readonly void UnsafeSetTargetToNull()
         {
             InternalSetTargetToNull(_handle);
         }
@@ -209,7 +209,7 @@ internal void UnsafeSetTargetToNull()
         /// Sets the dependent object instance for the current handle.
         /// </summary>
         /// <remarks>This method mirrors <see cref="Dependent"/>, but without the allocation check.</remarks>
-        internal void UnsafeSetDependent(object? dependent)
+        internal readonly void UnsafeSetDependent(object? dependent)
         {
             InternalSetDependent(_handle, dependent);
         }

src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/GCHandle.cs

@@ -78,7 +78,7 @@ public void Free()
         // Target property - allows getting / updating of the handle's referent.
         public object? Target
         {
-            get
+            readonly get
             {
                 IntPtr handle = _handle;
                 ThrowIfInvalid(handle);
@@ -103,7 +103,7 @@ public object? Target
         /// Retrieve the address of an object in a Pinned handle.  This throws
         /// an exception if the handle is any type other than Pinned.
         /// </summary>
-        public IntPtr AddrOfPinnedObject()
+        public readonly IntPtr AddrOfPinnedObject()
         {
             // Check if the handle was not a pinned handle.
             // You can only get the address of pinned handles.
@@ -141,7 +141,7 @@ public IntPtr AddrOfPinnedObject()
         }
 
         /// <summary>Determine whether this handle has been allocated or not.</summary>
-        public bool IsAllocated => (nint)_handle != 0;
+        public readonly bool IsAllocated => (nint)_handle != 0;
 
         /// <summary>
         /// Used to create a GCHandle from an int.  This is intended to
@@ -160,14 +160,14 @@ public static GCHandle FromIntPtr(IntPtr value)
 
         public static IntPtr ToIntPtr(GCHandle value) => value._handle;
 
-        public override int GetHashCode() => _handle.GetHashCode();
+        public override readonly int GetHashCode() => _handle.GetHashCode();
 
-        public override bool Equals([NotNullWhen(true)] object? o) => o is GCHandle other && Equals(other);
+        public override readonly bool Equals([NotNullWhen(true)] object? o) => o is GCHandle other && Equals(other);
 
         /// <summary>Indicates whether the current instance is equal to another instance of the same type.</summary>
         /// <param name="other">An instance to compare with this instance.</param>
         /// <returns>true if the current instance is equal to the other instance; otherwise, false.</returns>
-        public bool Equals(GCHandle other) => _handle == other._handle;
+        public readonly bool Equals(GCHandle other) => _handle == other._handle;
 
         public static bool operator ==(GCHandle a, GCHandle b) => (nint)a._handle == (nint)b._handle;
 

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

@@ -12428,10 +12428,10 @@ public partial struct DependentHandle : System.IDisposable
         private object _dummy;
         private int _dummyPrimitive;
         public DependentHandle(object? target, object? dependent) { throw null; }
-        public object? Dependent { get { throw null; } set { } }
-        public bool IsAllocated { get { throw null; } }
-        public object? Target { get { throw null; } set { } }
-        public (object? Target, object? Dependent) TargetAndDependent { get { throw null; } }
+        public object? Dependent { readonly get { throw null; } set { } }
+        public readonly bool IsAllocated { get { throw null; } }
+        public object? Target { readonly get { throw null; } set { } }
+        public readonly (object? Target, object? Dependent) TargetAndDependent { get { throw null; } }
         public void Dispose() { }
     }
     public enum GCLargeObjectHeapCompactionMode
@@ -13455,16 +13455,16 @@ public FieldOffsetAttribute(int offset) { }
     public partial struct GCHandle : System.IEquatable<System.Runtime.InteropServices.GCHandle>
     {
         private int _dummyPrimitive;
-        public bool IsAllocated { get { throw null; } }
-        public object? Target { get { throw null; } set { } }
-        public System.IntPtr AddrOfPinnedObject() { throw null; }
+        public readonly bool IsAllocated { get { throw null; } }
+        public object? Target { readonly get { throw null; } set { } }
+        public readonly System.IntPtr AddrOfPinnedObject() { throw null; }
         public static System.Runtime.InteropServices.GCHandle Alloc(object? value) { throw null; }
         public static System.Runtime.InteropServices.GCHandle Alloc(object? value, System.Runtime.InteropServices.GCHandleType type) { throw null; }
-        public override bool Equals([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] object? o) { throw null; }
-        public bool Equals(System.Runtime.InteropServices.GCHandle other) { throw null; }
+        public override readonly bool Equals([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] object? o) { throw null; }
+        public readonly bool Equals(System.Runtime.InteropServices.GCHandle other) { throw null; }
         public void Free() { }
         public static System.Runtime.InteropServices.GCHandle FromIntPtr(System.IntPtr value) { throw null; }
-        public override int GetHashCode() { throw null; }
+        public override readonly int GetHashCode() { throw null; }
         public static bool operator ==(System.Runtime.InteropServices.GCHandle a, System.Runtime.InteropServices.GCHandle b) { throw null; }
         public static explicit operator System.Runtime.InteropServices.GCHandle (System.IntPtr value) { throw null; }
         public static explicit operator System.IntPtr (System.Runtime.InteropServices.GCHandle value) { throw null; }