Add new TargetBuiltReasons

src/Build/BackEnd/Components/RequestBuilder/TargetBuilder.cs

@@ -153,7 +153,21 @@ public async Task<BuildResult> BuildTargets(ProjectLoggingContext loggingContext
                 }
                 else
                 {
-                    targets.Add(new TargetSpecification(targetName, targetExists ? targetInstance.Location : _projectInstance.ProjectFileLocation));
+                    TargetBuiltReason buildReason = TargetBuiltReason.None;
+                    if (entry.Request.Targets.Contains(targetName))
+                    {
+                        buildReason = TargetBuiltReason.EntryTarget;
+                    }
+                    else if (configuration.ProjectInitialTargets.Contains(targetName))
+                    {
+                        buildReason = TargetBuiltReason.InitialTarget;
+                    } 
+                    else if (configuration.ProjectDefaultTargets.Contains(targetName))
+                    {
+                        buildReason = TargetBuiltReason.DefaultTarget;
+                    }
+
+                    targets.Add(new TargetSpecification(targetName, targetExists ? targetInstance.Location : _projectInstance.ProjectFileLocation, buildReason));
                 }
             }
 
@@ -737,7 +751,15 @@ private async Task<bool> PushTargets(IList<TargetSpecification> targets, TargetE
 
                 // Add to the list of targets to push.  We don't actually put it on the stack here because we could run into a circular dependency
                 // during this loop, in which case the target stack would be out of whack.
-                TargetEntry newEntry = new TargetEntry(_requestEntry, this as ITargetBuilderCallback, targetSpecification, baseLookup, parentTargetEntry, buildReason, _componentHost, stopProcessingOnCompletion);
+                TargetEntry newEntry;
+                if (buildReason == TargetBuiltReason.None)
+                {
+                    newEntry = new TargetEntry(_requestEntry, this as ITargetBuilderCallback, targetSpecification, baseLookup, parentTargetEntry, targetSpecification._targetBuiltReason, _componentHost, stopProcessingOnCompletion);
+                }
+                else
+                {
+                    newEntry = new TargetEntry(_requestEntry, this as ITargetBuilderCallback, targetSpecification, baseLookup, parentTargetEntry, buildReason, _componentHost, stopProcessingOnCompletion);
+                }
                 newEntry.ErrorTarget = addAsErrorTarget;
                 targetsToPush.Add(newEntry);
                 stopProcessingOnCompletion = false; // The first target on the stack (the last one to be run) always inherits the stopProcessing flag.

src/Build/BackEnd/Components/RequestBuilder/TargetSpecification.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using Microsoft.Build.Framework;
 using Microsoft.Build.Shared;
 using ElementLocation = Microsoft.Build.Construction.ElementLocation;
 
@@ -18,18 +19,22 @@ internal class TargetSpecification : ITranslatable
         private string _targetName;
         private ElementLocation _referenceLocation;
 
+        internal TargetBuiltReason _targetBuiltReason;
+
         /// <summary>
         /// Construct a target specification.
         /// </summary>
         /// <param name="targetName">The name of the target</param>
         /// <param name="referenceLocation">The location from which it was referred.</param>
-        internal TargetSpecification(string targetName, ElementLocation referenceLocation)
+        /// <param name="targetBuiltReason">Reason the target is being built</param>
+        internal TargetSpecification(string targetName, ElementLocation referenceLocation, TargetBuiltReason targetBuiltReason = TargetBuiltReason.None)
         {
             ErrorUtilities.VerifyThrowArgumentLength(targetName, nameof(targetName));
             ErrorUtilities.VerifyThrowArgumentNull(referenceLocation, nameof(referenceLocation));
 
             this._targetName = targetName;
             this._referenceLocation = referenceLocation;
+            this._targetBuiltReason = targetBuiltReason;
         }
 
         private TargetSpecification()
@@ -41,6 +46,8 @@ private TargetSpecification()
         /// </summary>
         public string TargetName => _targetName;
 
+        public TargetBuiltReason TargetBuiltReason => _targetBuiltReason;
+
         /// <summary>
         /// Gets or sets the reference location
         /// </summary>

src/Framework/TargetBuiltReason.cs

@@ -28,6 +28,22 @@ public enum TargetBuiltReason
         /// <summary>
         /// The target was part of the parent's AfterTargets list.
         /// </summary>
-        AfterTargets
+        AfterTargets,
+
+        /// <summary>
+        /// The target was defined as an initial target of the project.
+        /// </summary>
+        InitialTarget,
+
+
+        /// <summary>
+        /// The target was the default target of the project
+        /// </summary>
+        DefaultTarget,
+
+        /// <summary>
+        /// The target was the target explicitly called to be built.
+        /// </summary>
+        EntryTarget
     }
 }