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

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

We currently only use a response file for .java files.
Looking at the docs there is no reason why we can't use
them for all of the arguments. This should help with
problems where windows has a max command line length.

Author: dellis1972

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

@@ -172,21 +172,6 @@ static string GetNdkToolchainLibraryDir (string binDir, AndroidTargetArch arch)
 			return GetNdkToolchainLibraryDir (binDir, NdkUtil.GetArchDirName (arch));
 		}
 
-		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;
@@ -380,20 +365,19 @@ IEnumerable<Config> GetAotConfigs ()
 
 					var libs = new List<string>();
 					if (NdkUtil.UsingClangNDK) {
-						libs.Add ($"-L{GetShortPath (toolchainLibDir)}");
-						libs.Add ($"-L{GetShortPath (androidLibPath)}");
+						libs.Add ($"-L{Files.GetShortPath (toolchainLibDir)}");
+						libs.Add ($"-L{Files.GetShortPath (androidLibPath)}");
 
 						if (arch == AndroidTargetArch.Arm) {
 							// Needed for -lunwind to work
 							string compilerLibDir = Path.Combine (toolchainPath, "..", "sysroot", "usr", "lib", NdkUtil.GetArchDirName (arch));
-							libs.Add ($"-L{GetShortPath (compilerLibDir)}");
+							libs.Add ($"-L{Files.GetShortPath (compilerLibDir)}");
 						}
 					}
 
-					libs.Add (GetShortPath (Path.Combine (toolchainLibDir, "libgcc.a")));
-					libs.Add (GetShortPath (Path.Combine (androidLibPath, "libc.so")));
-					libs.Add (GetShortPath (Path.Combine (androidLibPath, "libm.so")));
-
+					libs.Add (Files.GetShortPath (Path.Combine (toolchainLibDir, "libgcc.a")));
+					libs.Add (Files.GetShortPath (Path.Combine (androidLibPath, "libc.so")));
+					libs.Add (Files.GetShortPath (Path.Combine (androidLibPath, "libm.so")));
 					ldFlags = string.Join(";", libs);
 				}
 
@@ -420,17 +404,17 @@ 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);
 
@@ -452,9 +436,9 @@ 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

@@ -52,12 +52,18 @@ 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

@@ -8,6 +8,7 @@
 using System.Text;
 using System.Collections.Generic;
 using Xamarin.Tools.Zip;
+using Xamarin.Android.Tools;
 
 namespace Xamarin.Android.Tasks
 {
@@ -50,16 +51,19 @@ 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 ($"-d {Files.GetShortPath (ClassesOutputDirectory).Replace (@"\", "\\")}");
+			sw.WriteLine ("-classpath \"{0}\"", Jars == null || !Jars.Any () ? null : string.Join (Path.PathSeparator.ToString (), Jars.Select (i => i.ItemSpec.Replace (@"\", "\\"))));
+			sw.WriteLine ("-bootclasspath {0}", Files.GetShortPath (JavaPlatformJarPath).Replace (@"\", "\\"));
+			sw.WriteLine ($"-encoding UTF8");
+		}
 	}
 }

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

@@ -401,6 +401,21 @@ 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));
+		}
 	}
 }