Imported Upstream version 5.14.0.78

Former-commit-id: 3494343bcc9ddb42b36b82dd9ae7b69e85e0229f

external/linker/corebuild/integration/ILLink.Tasks/FindDuplicatesByMetadata.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+
+namespace ILLink.Tasks
+{
+	public class FindDuplicatesByMetadata : Task
+	{
+		/// <summary>
+		///   Items to scan.
+		/// </summary>
+		[Required]
+		public ITaskItem [] Items { get; set; }
+
+		/// <summary>
+		///   Name of metadata to scan for.
+		/// </summary>
+		[Required]
+		public String MetadataName { get; set; }
+
+		/// <summary>
+		///   Duplicate items: the input items for which the
+		///   specified metadata was shared by multiple input
+		///   items.
+		/// </summary>
+		[Output]
+		public ITaskItem [] DuplicateItems { get; set; }
+
+		/// <summary>
+		///   Duplicate representatives: includes one input
+		///   item from each set of duplicates.
+		/// </summary>
+		[Output]
+		public ITaskItem [] DuplicateRepresentatives { get; set; }
+
+		public override bool Execute ()
+		{
+			var duplicateGroups = Items.GroupBy (i => i.GetMetadata (MetadataName))
+				.Where (g => g.Count () > 1);
+			DuplicateItems = duplicateGroups.SelectMany (g => g).ToArray ();
+			DuplicateRepresentatives = duplicateGroups.Select (g => g.First ()).ToArray ();
+			return true;
+		}
+	}
+}