[Xamarin.Android.Build.Tasks] _CleanGeneratedDebuggingFiles removes *.pdb (#733)

Fixes: https://bugzilla.xamarin.com/show_bug.cgi?id=58646

Rather than just blindly delete ALL the debug files in the
`$(OutputPath)` we should be a bit more selective.

So instead we add the generated files to the file

	$(IntermediateOutputPath)$(CleanFile)

so that they can be cleaned up automatically using the in-build
xbuild/msbuild Clean systems.

Author: dellis1972

src/Xamarin.Android.Build.Tasks/Tasks/ConvertDebuggingFiles.cs

@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using System.Collections.Generic;
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
 using Pdb2Mdb;
@@ -12,11 +13,15 @@ public class ConvertDebuggingFiles : Task
 		[Required]
 		public ITaskItem[] Files { get; set; }
 
+		[Output]
+		public ITaskItem[] ConvertedFiles { get; set; }
+
 		public override bool Execute ()
 		{
 			Log.LogDebugMessage ("ConvertDebuggingFiles Task");
 			Log.LogDebugMessage ("  InputFiles: {0}", Files);
 
+			var convertedFiles = new List<ITaskItem> ();
 			foreach (var file in Files) {
 				var pdb = file.ToString ();
 
@@ -26,11 +31,13 @@ public override bool Execute ()
 				try {
 					MonoAndroidHelper.SetWriteable (pdb);
 					Converter.Convert (Path.ChangeExtension (pdb, ".dll"));
+					convertedFiles.Add (new TaskItem (Path.ChangeExtension (pdb, ".dll")));
 				} catch (Exception ex) {
 					Log.LogWarningFromException (ex, true);
 				}
 			}
-
+			ConvertedFiles = convertedFiles.ToArray ();
+			Log.LogDebugTaskItems ("[Output] ConvertedFiles:", ConvertedFiles);
 			return true;
 		}
 	}

src/Xamarin.Android.Build.Tasks/Tasks/CopyMdbFiles.cs

@@ -2,6 +2,7 @@
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
 using System.IO;
+using System.Collections.Generic;
 using Xamarin.Android.Tools;
 
 namespace Xamarin.Android.Tasks {
@@ -12,23 +13,31 @@ public class CopyMdbFiles : Task {
 
 		public ITaskItem[] DestinationFiles { get; set; }
 
+		[Output]
+		public ITaskItem[] CopiedFiles { get; set; }
+
 		public override bool Execute() {
 			Log.LogDebugTaskItems ("SourceFiles:", SourceFiles);
 			Log.LogDebugTaskItems ("DestinationFiles:", DestinationFiles);
 
 			if (SourceFiles.Length != DestinationFiles.Length)
 				throw new ArgumentException ("source and destination count mismatch");
 
+			var copiedFiles = new List<ITaskItem> ();
 			for (int i = 0; i < SourceFiles.Length; i++) {
 				var src = SourceFiles[i].ItemSpec;
 				if (File.Exists (src)) {
 					var dst = DestinationFiles [i].ItemSpec;
 					var date = DateTime.Now;
-					MonoAndroidHelper.CopyIfChanged (src, dst);
-					MonoAndroidHelper.SetWriteable (dst);
-					MonoAndroidHelper.SetLastAccessAndWriteTimeUtc (dst, date, Log);
+					if (MonoAndroidHelper.CopyIfChanged (src, dst)) {
+						copiedFiles.Add (DestinationFiles [i]);
+						MonoAndroidHelper.SetWriteable (dst);
+						MonoAndroidHelper.SetLastAccessAndWriteTimeUtc (dst, date, Log);
+					}
 				}
 			}
+			CopiedFiles = copiedFiles.ToArray ();
+			Log.LogDebugTaskItems ("[Output] CopiedFiles:", CopiedFiles);
 			return true;
 		}
 	}

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets

@@ -1557,7 +1557,13 @@ because xbuild doesn't support framework reference assemblies.
 		Inputs="@(_ResolvedPdbFiles)"
 		Outputs="@(_ResolvedPdbFiles->'%(RootDir)%(Directory)%(Filename).dll.mdb')"
 		DependsOnTargets="_CollectPdbFiles">
-	<ConvertDebuggingFiles Files="@(_ResolvedPdbFiles)" />
+	<ConvertDebuggingFiles Files="@(_ResolvedPdbFiles)">
+		<Output TaskParameter="ConvertedFiles" ItemName="_ConvertedDebuggingFiles" />
+	</ConvertDebuggingFiles>
+	<WriteLinesToFile
+		File="$(IntermediateOutputPath)$(CleanFile)"
+		Lines="@(_ConvertedDebuggingFiles)"
+		Overwrite="false" />
 </Target>
 
 <Target Name="_CopyMdbFiles"
@@ -1566,13 +1572,20 @@ because xbuild doesn't support framework reference assemblies.
 		DependsOnTargets="_ConvertPdbFiles;_CollectMdbFiles" >
 	<CopyMdbFiles
 			SourceFiles="@(_ResolvedMdbFiles);@(_ResolvedPortablePdbFiles)"
-			DestinationFiles="@(_ResolvedMdbFiles->'$(OutputPath)%(Filename)%(Extension)');@(_ResolvedPortablePdbFiles->'$(OutputPath)%(Filename)%(Extension)')"
-	/>
+			DestinationFiles="@(_ResolvedMdbFiles->'$(OutputPath)%(Filename)%(Extension)');@(_ResolvedPortablePdbFiles->'$(OutputPath)%(Filename)%(Extension)')">
+		<Output TaskParameter="CopiedFiles" ItemName="_MdbFilesCopied" />
+	</CopyMdbFiles>
 	<Copy
-		SourceFiles="@(_ResolvedMdbFiles->'$(OutputPath)%(Filename)%(Extension)');@(_ResolvedPortablePdbFiles->'$(OutputPath)%(Filename)%(Extension)')"
-		DestinationFiles="@(_ResolvedMdbFiles->'$(MonoAndroidLinkerInputDir)%(Filename)%(Extension)');@(_ResolvedPortablePdbFiles->'$(MonoAndroidLinkerInputDir)%(Filename)%(Extension)')"
-		SkipUnchangedFiles="true"
-	/>
+			SourceFiles="@(_ResolvedMdbFiles->'$(OutputPath)%(Filename)%(Extension)');@(_ResolvedPortablePdbFiles->'$(OutputPath)%(Filename)%(Extension)')"
+			DestinationFiles="@(_ResolvedMdbFiles->'$(MonoAndroidLinkerInputDir)%(Filename)%(Extension)');@(_ResolvedPortablePdbFiles->'$(MonoAndroidLinkerInputDir)%(Filename)%(Extension)')"
+			SkipUnchangedFiles="true">
+		<Output TaskParameter="CopiedFiles" ItemName="_DebugFilesCopiedToLinkerSrc" />
+	</Copy>
+	<Touch Files="@(_DebugFilesCopiedToLinkerSrc)" />
+	<WriteLinesToFile
+		File="$(IntermediateOutputPath)$(CleanFile)"
+		Lines="@(_MdbFilesCopied);@(_DebugFilesCopiedToLinkerSrc)"
+		Overwrite="false" />
 </Target>
 
 <Target Name="_LinkAssemblies"
@@ -2409,13 +2422,6 @@ because xbuild doesn't support framework reference assemblies.
 
 <!-- Cleaning -->
 
-<Target Name="_CleanGeneratedDebuggingFiles">
-	<ItemGroup>
-		<_OutputDebugSymbolFiles Include="$(OutputPath)*.dll.mdb;$(OutputPath)*.pdb" />
-	</ItemGroup>
-	<Delete Files="@(_OutputDebugSymbolFiles)"/>
-</Target>
-
 <Target Name="_CleanMsymArchive">
 	<GetAndroidPackageName ManifestFile="$(ProjectDir)$(AndroidManifest)" AssemblyName="$(AssemblyName)">
 		<Output TaskParameter="PackageName" PropertyName="_AndroidPackage" />
@@ -2430,7 +2436,7 @@ because xbuild doesn't support framework reference assemblies.
 	<Delete Files="@(_OutputDeploymentFiles)"/>
 </Target>
 
-<Target Name="_CleanMonoAndroidIntermediateDir" DependsOnTargets="_CleanGeneratedDebuggingFiles;_CleanGeneratedDeploymentFiles;_CleanMsymArchive">
+<Target Name="_CleanMonoAndroidIntermediateDir" DependsOnTargets="_CleanGeneratedDeploymentFiles;_CleanMsymArchive">
 	<RemoveDirFixed Directories="$(MonoAndroidIntermediate)android" Condition="Exists ('$(MonoAndroidIntermediate)android')" />
 	<!-- FIXME: remove this extraneous rmdir after a few release cycles since we release the one we killed it. -->
 	<RemoveDirFixed Directories="$(MonoAndroidIntermediate)assemblies" Condition="Exists ('$(MonoAndroidIntermediate)assemblies')" />