[Xamarin.Android.Build.Tasks] Use a Response file for javac

Context https://devdiv.visualstudio.com/DevDiv/_workitems/edit/599161

We currently only use a resposen file for .java files.
Looking at the docs there is no reason why we can't use
them for all of the arguments.

Using a response file should get rid of the following
errors

	error MSB4018: System.IO.PathTooLongException: The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.

for `javac` anyway.

Author: dellis1972

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

@@ -148,21 +148,6 @@ static string GetNdkToolchainLibraryDir(string binDir)
 			return libPath;
 		}
 
-		static string GetShortPath (string path)
-		{
-			if (Environment.OSVersion.Platform != PlatformID.Win32NT)
-				return QuoteFileName (path);
-			var shortPath = KernelEx.GetShortPathName (Path.GetDirectoryName (path));
-			return Path.Combine (shortPath, Path.GetFileName (path));
-		}
-
-		static string QuoteFileName(string fileName)
-		{
-			var builder = new CommandLineBuilder();
-			builder.AppendFileNameIfNotNull(fileName);
-			return builder.ToString();
-		}
-
 		static bool ValidateAotConfiguration (TaskLoggingHelper log, AndroidTargetArch arch, bool enableLLVM)
 		{
 			return true;
@@ -388,9 +373,9 @@ IEnumerable<Config> GetAotConfigs ()
 						Diagnostic.Error (5101, ex.Message);
 					}
 					var libs = new List<string>() {
-						GetShortPath (Path.Combine(GetNdkToolchainLibraryDir(toolchainPath), "libgcc.a")),
-						GetShortPath (Path.Combine(androidLibPath, "libc.so")),
-						GetShortPath (Path.Combine(androidLibPath, "libm.so"))
+						Files.GetShortPath (Path.Combine(GetNdkToolchainLibraryDir(toolchainPath), "libgcc.a")),
+						Files.GetShortPath (Path.Combine(androidLibPath, "libc.so")),
+						Files.GetShortPath (Path.Combine(androidLibPath, "libm.so"))
 					};
 					ldFlags = string.Join(";", libs);
 				}
@@ -411,17 +396,17 @@ IEnumerable<Config> GetAotConfigs ()
 					if (!string.IsNullOrEmpty (AotAdditionalArguments))
 						aotOptions.Add (AotAdditionalArguments);
 					if (sequencePointsMode == SequencePointsMode.Offline)
-						aotOptions.Add ("msym-dir=" + GetShortPath (outdir));
+						aotOptions.Add ("msym-dir=" + Files.GetShortPath (outdir));
 					if (AotMode != AotMode.Normal)
 						aotOptions.Add (AotMode.ToString ().ToLowerInvariant ());
 
-					aotOptions.Add ("outfile="     + GetShortPath (outputFile));
+					aotOptions.Add ("outfile="     + Files.GetShortPath (outputFile));
 					aotOptions.Add ("asmwriter");
 					aotOptions.Add ("mtriple="     + mtriple);
-					aotOptions.Add ("tool-prefix=" + GetShortPath (toolPrefix));
+					aotOptions.Add ("tool-prefix=" + Files.GetShortPath (toolPrefix));
 					aotOptions.Add ("ld-flags="    + ldFlags);
-					aotOptions.Add ("llvm-path="   + GetShortPath (sdkBinDirectory));
-					aotOptions.Add ("temp-path="   + GetShortPath (tempDir));
+					aotOptions.Add ("llvm-path="   + Files.GetShortPath (sdkBinDirectory));
+					aotOptions.Add ("temp-path="   + Files.GetShortPath (tempDir));
 
 					string aotOptionsStr = (EnableLLVM ? "--llvm " : "") + "--aot=" + string.Join (",", aotOptions);
 
@@ -443,9 +428,9 @@ IEnumerable<Config> GetAotConfigs ()
 					}
 
 					var assembliesPath = Path.GetFullPath (Path.GetDirectoryName (resolvedPath));
-					var assemblyPath = QuoteFileName (Path.GetFullPath (resolvedPath));
+					var assemblyPath = Files.QuoteFileName (Path.GetFullPath (resolvedPath));
 
-					yield return new Config (assembliesPath, QuoteFileName (aotCompiler), aotOptionsStr, assemblyPath, outputFile);
+					yield return new Config (assembliesPath, Files.QuoteFileName (aotCompiler), aotOptionsStr, assemblyPath, outputFile);
 				}
 			}
 		}

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

@@ -63,12 +63,18 @@ public override bool Execute ()
 			return retval;
 		}
 
+		protected virtual void WriteOptionsToResponseFile (StreamWriter sw)
+		{
+		}
+
 		private void GenerateResponseFile ()
 		{
 			TemporarySourceListFile = Path.GetTempFileName ();
 
 			using (var sw = new StreamWriter (path:TemporarySourceListFile, append:false,
 						encoding:new UTF8Encoding (encoderShouldEmitUTF8Identifier:false))) {
+
+				WriteOptionsToResponseFile (sw);
 				// Include any user .java files
 				if (JavaSourceFiles != null)
 					foreach (var file in JavaSourceFiles.Where (p => Path.GetExtension (p.ItemSpec) == ".java"))

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

@@ -7,6 +7,7 @@
 using Microsoft.Build.Utilities;
 using System.Text;
 using System.Collections.Generic;
+using Xamarin.Android.Tools;
 
 namespace Xamarin.Android.Tasks
 {
@@ -56,16 +57,19 @@ protected override string GenerateCommandLineCommands ()
 
 			cmd.AppendSwitchIfNotNull ("-J-Dfile.encoding=", "UTF8");
 
-			cmd.AppendSwitchIfNotNull ("-d ", ClassesOutputDirectory);
-
-			cmd.AppendSwitchIfNotNull ("-classpath ", Jars == null || !Jars.Any () ? null : string.Join (Path.PathSeparator.ToString (), Jars.Select (i => i.ItemSpec)));
-			cmd.AppendSwitchIfNotNull ("-bootclasspath ", JavaPlatformJarPath);
-			cmd.AppendSwitchIfNotNull ("-encoding ", "UTF-8");
 			cmd.AppendFileNameIfNotNull (string.Format ("@{0}", TemporarySourceListFile));
 			cmd.AppendSwitchIfNotNull ("-target ", JavacTargetVersion);
 			cmd.AppendSwitchIfNotNull ("-source ", JavacSourceVersion);
 
 			return cmd.ToString ();
 		}
+
+		protected override void WriteOptionsToResponseFile (StreamWriter sw)
+		{
+			sw.WriteLine ($"-d {ClassesOutputDirectory}");
+			sw.WriteLine ("-classpath {0}", Jars == null || !Jars.Any () ? null : string.Join (Path.PathSeparator.ToString (), Jars.Select (i => Files.GetShortPath (i.ItemSpec).Replace (@"\", @"\\"))));
+			sw.WriteLine ("-bootclasspath {0}", Files.GetShortPath (JavaPlatformJarPath).Replace (@"\", @"\\"));
+			sw.WriteLine ($"-encoding UTF8");
+		}
 	}
 }

src/Xamarin.Android.Build.Tasks/Utilities/Files.cs

@@ -310,6 +310,21 @@ public static bool IsPortablePdb (string filename)
 				return false;
 			}
 		}
+
+		internal static string QuoteFileName(string fileName)
+		{
+			var builder = new CommandLineBuilder();
+			builder.AppendFileNameIfNotNull(fileName);
+			return builder.ToString();
+		}
+
+		internal static string GetShortPath (string path)
+		{
+			if (Environment.OSVersion.Platform != PlatformID.Win32NT)
+				return QuoteFileName (path);
+			var shortPath = KernelEx.GetShortPathName (Path.GetDirectoryName (path));
+			return Path.Combine (shortPath, Path.GetFileName (path));
+		}
 	}
 }