Add OverloadResolutionPriorityAttribute

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -877,6 +877,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\PoolingAsyncValueTaskMethodBuilder.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\PoolingAsyncValueTaskMethodBuilderT.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\PreserveBaseOverridesAttribute.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\OverloadResolutionPriorityAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\RefSafetyRulesAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\RequiredMemberAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\RequiresLocationAttribute.cs" />

src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/OverloadResolutionPriorityAttribute.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>
+    /// Specifies the priority of a member in overload resolution. When unspecified, the default priority is 0.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor | AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
+    public sealed class OverloadResolutionPriorityAttribute : Attribute
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OverloadResolutionPriorityAttribute"/> class.
+        /// </summary>
+        /// <param name="priority">The priority of the attributed member. Higher numbers are prioritized, lower numbers are deprioritized. 0 is the default if no attribute is present.</param>
+        public OverloadResolutionPriorityAttribute(int priority)
+        {
+            Priority = priority;
+        }
+
+        /// <summary>
+        /// The priority of the member.
+        /// </summary>
+        public int Priority { get; }
+    }
+}

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

@@ -13091,6 +13091,12 @@ public sealed partial class NullablePublicOnlyAttribute : System.Attribute
         public readonly bool IncludesInternals;
         public NullablePublicOnlyAttribute(bool value) { }
     }
+    [System.AttributeUsageAttribute(System.AttributeTargets.Method | System.AttributeTargets.Constructor | System.AttributeTargets.Property, AllowMultiple=false, Inherited=false)]
+    public sealed partial class OverloadResolutionPriorityAttribute : System.Attribute
+    {
+        public OverloadResolutionPriorityAttribute(int priority) { }
+		public int Priority { get { throw null; } }
+    }
     [System.AttributeUsageAttribute(System.AttributeTargets.Parameter, Inherited = true, AllowMultiple = false)]
     public sealed partial class ParamCollectionAttribute : System.Attribute
     {

src/libraries/System.Runtime/tests/System.Runtime.Tests/System/Runtime/CompilerServices/AttributesTests.cs

@@ -399,5 +399,12 @@ public static void RequiresLocationAttributeTests()
         {
             new RequiresLocationAttribute();
         }
+
+        [Fact]
+        public static void OverloadResolutionPriorityAttributeTests()
+        {
+            var attr = new OverloadResolutionPriorityAttribute(42);
+            Assert.Equal(42, attr.Priority);
+        }
     }
 }