[WIP] Don't generate empty include files

Author: grendello

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

@@ -49,12 +49,24 @@ protected override void WriteSymbols (StreamWriter output)
 			output.WriteLine ();
 			WriteHeaderField (output, "java_name_width", mappingData.JavaNameWidth);
 
+			bool haveAssemblyNames = mappingData.AssemblyNames.Count > 0;
+			bool haveModules = mappingData.Modules.Count > 0;
+
 			output.WriteLine ();
-			output.WriteLine ($"{Indent}.include{Indent}\"{Path.GetFileName (SharedIncludeFile)}\"");
-			output.WriteLine ($"{Indent}.include{Indent}\"{Path.GetFileName (TypemapsIncludeFile)}\"");
+			if (haveAssemblyNames) {
+				output.WriteLine ($"{Indent}.include{Indent}\"{Path.GetFileName (SharedIncludeFile)}\"");
+			} else {
+				WriteCommentLine (output, $"No shared data present, {Path.GetFileName (SharedIncludeFile)} not generated");
+			}
+
+			if (haveModules) {
+				output.WriteLine ($"{Indent}.include{Indent}\"{Path.GetFileName (TypemapsIncludeFile)}\"");
+			} else {
+				WriteCommentLine (output, $"No modules defined, {Path.GetFileName (TypemapsIncludeFile)} not generated");
+			}
 			output.WriteLine ();
 
-			if (!sharedBitsWritten) {
+			if (!sharedBitsWritten && haveAssemblyNames) {
 				using (var fs = File.Open (SharedIncludeFile, FileMode.Create)) {
 					using (var sharedOutput = new StreamWriter (fs, output.Encoding)) {
 						WriteAssemblyNames (sharedOutput);
@@ -63,10 +75,14 @@ protected override void WriteSymbols (StreamWriter output)
 				}
 			}
 
-			using (var fs = File.Open (TypemapsIncludeFile, FileMode.Create)) {
-				using (var mapOutput = new StreamWriter (fs, output.Encoding)) {
-					WriteMapModules (output, mapOutput, "map_modules");
+			if (haveModules) {
+				using (var fs = File.Open (TypemapsIncludeFile, FileMode.Create)) {
+					using (var mapOutput = new StreamWriter (fs, output.Encoding)) {
+						WriteMapModules (output, mapOutput, "map_modules");
+					}
 				}
+			} else {
+				WriteMapModules (output, null, "map_modules");
 			}
 
 			WriteJavaMap (output, "map_java");
@@ -128,7 +144,8 @@ void WriteMapModules (StreamWriter output, StreamWriter mapOutput, string symbol
 
 				string mapName = $"module{moduleCounter++}_managed_to_java";
 				size += WriteStructure (output, fieldAlignBytes, () => WriteMapModule (output, mapName, mvid, data));
-				WriteManagedMaps (mapOutput, mapName, data);
+				if (mapOutput != null)
+					WriteManagedMaps (mapOutput, mapName, data);
 			}
 
 			WriteStructureSize (output, symbolName, size);