Feature Query API

src/Build.UnitTests/Evaluation/Expander_Tests.cs

@@ -4333,6 +4333,18 @@ public void PropertyFunctionGuidNewGuid()
             Assert.True(Guid.TryParse(result, out Guid guid));
         }
 
+        // TODO: update features list
+        [Theory]
+        [InlineData("NonExistingFeature", "Undefined")]
+        public void PropertyFunctionCheckFeatureAvailability(string featureName, string availability)
+        {
+            var expander = new Expander<ProjectPropertyInstance, ProjectItemInstance>(new PropertyDictionary<ProjectPropertyInstance>(), FileSystems.Default);
+
+            var result = expander.ExpandIntoStringLeaveEscaped($"$([MSBuild]::CheckFeatureAvailability({featureName}))", ExpanderOptions.ExpandProperties, MockElementLocation.Instance);
+
+            Assert.Equal(availability, result);
+        }
+
         [Fact]
         public void PropertyFunctionIntrinsicFunctionGetCurrentToolsDirectory()
         {

src/Build/Evaluation/Expander.cs

@@ -4171,6 +4171,14 @@ private bool TryExecuteWellKnownFunction(out object returnVal, object objectInst
                                 return true;
                             }
                         }
+                        else if (string.Equals(_methodMethodName, nameof(IntrinsicFunctions.CheckFeatureAvailability), StringComparison.OrdinalIgnoreCase))
+                        {
+                            if (TryGetArg(args, out string arg0))
+                            {
+                                returnVal = IntrinsicFunctions.CheckFeatureAvailability(arg0);
+                                return true;
+                            }
+                        }
                         else if (string.Equals(_methodMethodName, nameof(IntrinsicFunctions.BitwiseOr), StringComparison.OrdinalIgnoreCase))
                         {
                             if (TryGetArgs(args, out int arg0, out int arg1))

src/Build/Evaluation/IntrinsicFunctions.cs

@@ -574,6 +574,11 @@ internal static bool AreFeaturesEnabled(Version wave)
             return ChangeWaves.AreFeaturesEnabled(wave);
         }
 
+        internal static string CheckFeatureAvailability(string featureName)
+        {
+            return Features.CheckFeatureAvailability(featureName).ToString();
+        }
+
         public static string GetCurrentToolsDirectory()
         {
             return BuildEnvironmentHelper.Instance.CurrentMSBuildToolsDirectory;

src/Framework/Features.cs

@@ -0,0 +1,59 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Microsoft.Build.Framework
+{
+    /// <summary>
+    /// The status of a feature.
+    /// </summary>
+    public enum FeatureStatus
+    {
+        /// <summary>
+        /// The feature availability is not determined.
+        /// </summary>
+        Undefined,
+
+        /// <summary>
+        /// The feature is available.
+        /// </summary>
+        Available,
+
+        /// <summary>
+        /// The feature is not available.
+        /// </summary>
+        NotAvailable,
+
+        /// <summary>
+        /// The feature is in preview, subject to change API or behavior between releases.
+        /// </summary>
+        Preview,
+    }
+
+    /// <summary>
+    /// This class is used to manage features.
+    /// </summary>
+    public static class Features
+    {
+        private static readonly Dictionary<string, FeatureStatus> _featureStatusMap = new Dictionary<string, FeatureStatus>
+        {
+            // TODO: Fill in the dictionary with the features and their status
+        };
+
+        /// <summary>
+        /// Checks if a feature is available or not.
+        /// </summary>
+        /// <param name="featureName">The name of the feature.</param>
+        /// <returns>A feature status <see cref="FeatureStatus"/>.</returns>
+        public static FeatureStatus CheckFeatureAvailability(string featureName)
+        {
+            return _featureStatusMap.TryGetValue(featureName, out FeatureStatus status) ?
+                 status : FeatureStatus.Undefined;
+        }
+    }
+}

src/MSBuild.UnitTests/CommandLineSwitches_Tests.cs

@@ -576,6 +576,26 @@ public void TargetsSwitchIdentificationTests(string @switch)
             emptyParametersAllowed.ShouldBeFalse();
         }
 
+        [Theory]
+        [InlineData("featureavailability")]
+        [InlineData("fa")]
+        public void FeatureAvailibilitySwitchIdentificationTest(string switchName)
+        {
+            CommandLineSwitches.IsParameterizedSwitch(
+                switchName,
+                out CommandLineSwitches.ParameterizedSwitch parameterizedSwitch,
+                out string duplicateSwitchErrorMessage,
+                out bool multipleParametersAllowed,
+                out string missingParametersErrorMessage,
+                out _,
+                out _);
+
+            parameterizedSwitch.ShouldBe(CommandLineSwitches.ParameterizedSwitch.FeatureAvailability);
+            duplicateSwitchErrorMessage.ShouldBeNull();
+            multipleParametersAllowed.ShouldBeTrue();
+            missingParametersErrorMessage.ShouldNotBeNullOrEmpty();
+        }
+
         [Fact]
         public void TargetsSwitchParameter()
         {

src/MSBuild/CommandLineSwitches.cs

@@ -50,6 +50,7 @@ internal enum ParameterlessSwitch
 #if DEBUG
             WaitForDebugger,
 #endif
+            // This has to be kept as last enum value
             NumberOfParameterlessSwitches
         }
 
@@ -115,6 +116,8 @@ internal enum ParameterizedSwitch
             GetProperty,
             GetItem,
             GetTargetResult,
+            FeatureAvailability,
+            // This has to be kept as last enum value
             NumberOfParameterizedSwitches,
         }
 
@@ -280,6 +283,7 @@ internal ParameterizedSwitchInfo(
             new ParameterizedSwitchInfo(  new string[] { "getProperty" },                       ParameterizedSwitch.GetProperty,                null,                           true,           "MissingGetPropertyError",             true,   false),
             new ParameterizedSwitchInfo(  new string[] { "getItem" },                           ParameterizedSwitch.GetItem,                    null,                           true,           "MissingGetItemError",                 true,   false),
             new ParameterizedSwitchInfo(  new string[] { "getTargetResult" },                   ParameterizedSwitch.GetTargetResult,            null,                           true,           "MissingGetTargetResultError",         true,   false),
+            new ParameterizedSwitchInfo(  new string[] { "featureavailability", "fa" },         ParameterizedSwitch.FeatureAvailability,        null,                           true,           "MissingFeatureAvailabilityError",     true,   false),
         };
 
         /// <summary>

src/MSBuild/Resources/Strings.resx

@@ -1053,6 +1053,14 @@
       LOCALIZATION: The prefix "MSBUILD : error MSBxxxx:" should not be localized.
     </comment>
   </data>
+  <data name="MissingFeatureAvailabilityError" UESanitized="true" Visibility="Public">
+    <value>MSBUILD : error MSB1067: Must provide a feature name for the featureavailability switch.</value>
+    <comment>
+      {StrBegin="MSBUILD : error MSB1067: "}UE: This happens if the user does something like "msbuild.exe -featureavailability". The user must pass in an actual feature name
+      following the switch, as in "msbuild.exe -featureavailability:blah".
+      LOCALIZATION: The prefix "MSBUILD : error MSBxxxx:" should not be localized.
+    </comment>
+  </data>
   <data name="MissingGetItemError" UESanitized="true" Visibility="Public">
     <value>MSBUILD : error MSB1014: Must provide an item name for the getItem switch.</value>
     <comment>
@@ -1559,7 +1567,7 @@
     <!--
         The command line message bucket is: MSB1001 - MSB1999
 
-        Next error code should be MSB1067.
+        Next error code should be MSB1068.
 
         Don't forget to update this comment after using the new code.
   -->