Fixes issue 176 more thoroughly; even if both javac6 and javac7 are on the classpath, the 'right' BaseFileObject wrapper is now used.

src/core/lombok/javac/apt/InterceptingJavaFileManager.java

@@ -32,23 +32,24 @@ import javax.tools.JavaFileObject.Kind;
 import lombok.core.DiagnosticsReceiver;
 
 final class InterceptingJavaFileManager extends ForwardingJavaFileManager<JavaFileManager> {
-	
 	private final DiagnosticsReceiver diagnostics;
+	private final LombokFileObjects.Compiler compiler;
 	
 	InterceptingJavaFileManager(JavaFileManager original, DiagnosticsReceiver diagnostics) {
 		super(original);
+		this.compiler = LombokFileObjects.getCompiler(original);
 		this.diagnostics = diagnostics;
 	}
 	
 	@Override public JavaFileObject getJavaFileForOutput(Location location, String className, final Kind kind, FileObject sibling) throws IOException {
 		if (className.startsWith("lombok.dummy.ForceNewRound")) {
 			final String name = className.replace(".", "/") + kind.extension;
-			return LombokFileObjects.createEmpty(name, kind);
+			return LombokFileObjects.createEmpty(compiler, name, kind);
 		}
 		JavaFileObject fileObject = fileManager.getJavaFileForOutput(location, className, kind, sibling);
 		if (kind != Kind.CLASS) {
 			return fileObject;
 		}
-		return LombokFileObjects.createIntercepting(fileObject, className, diagnostics);
+		return LombokFileObjects.createIntercepting(compiler, fileObject, className, diagnostics);
 	}
 }

src/core/lombok/javac/apt/LombokFileObjects.java

@@ -23,7 +23,9 @@
 package lombok.javac.apt;
 
 import java.lang.reflect.Method;
+import java.util.concurrent.atomic.AtomicBoolean;
 
+import javax.tools.JavaFileManager;
 import javax.tools.JavaFileObject;
 import javax.tools.JavaFileObject.Kind;
 
@@ -32,63 +34,81 @@ import lombok.core.DiagnosticsReceiver;
 //Can't use SimpleJavaFileObject so we copy/paste most of its content here, because javac doesn't follow the interface,
 //and casts to its own BaseFileObject type. D'oh!
 final class LombokFileObjects {
-	
-	private enum Compiler {
+	enum Compiler {
 		JAVAC6 {
+			private Method decoderMethod = null;
+			private final AtomicBoolean decoderIsSet = new AtomicBoolean();
+			
 			@Override public JavaFileObject wrap(LombokFileObject fileObject) {
 				return new Javac6BaseFileObjectWrapper(fileObject);
 			}
-		}, 
+			
+			@Override public Method getDecoderMethod() {
+				synchronized (decoderIsSet) {
+					if (decoderIsSet.get()) return decoderMethod;
+					decoderMethod = getDecoderMethod("com.sun.tools.javac.util.BaseFileObject");
+					decoderIsSet.set(true);
+					return decoderMethod;
+				}
+			}
+		},
 		JAVAC7 {
+			private Method decoderMethod = null;
+			private final AtomicBoolean decoderIsSet = new AtomicBoolean();
+			
 			@Override public JavaFileObject wrap(LombokFileObject fileObject) {
 				return new Javac7BaseFileObjectWrapper(fileObject);
 			}
+			
+			@Override public Method getDecoderMethod() {
+				synchronized (decoderIsSet) {
+					if (decoderIsSet.get()) return decoderMethod;
+					decoderMethod = getDecoderMethod("com.sun.tools.javac.util.BaseFileObject");
+					decoderIsSet.set(true);
+					return decoderMethod;
+				}
+			}
 		};
 		
-		abstract JavaFileObject wrap(LombokFileObject fileObject);
-	}
-	
-	private static final Compiler compiler;
-	private static final Method decoderMethod;
-	
-	static {
-		Compiler c = null;
-		Method m = null;
-		try {
-			// In javac6, the BaseFileObject is located in 
-			// com.sun.tools.javac.util
-			Class<?> clazz = Class.forName("com.sun.tools.javac.util.BaseFileObject");
-			c = Compiler.JAVAC6;
+		static Method getDecoderMethod(String className) {
+			Method m = null;
 			try {
-				// The getDecoder method is not always present in javac6
-				m = clazz.getDeclaredMethod("getDecoder", boolean.class);
-			} catch (NoSuchMethodException e) {}
-		} catch (ClassNotFoundException cnfe) {
-			// In javac7, the BaseFileObject has been moved to the package 
-			// com.sun.tools.javac.file
-			try {
-				Class<?> clazz = Class.forName("com.sun.tools.javac.file.BaseFileObject");
-				c = Compiler.JAVAC7;
-				try {
-					m = clazz.getDeclaredMethod("getDecoder", boolean.class);
-				} catch (NoSuchMethodException e) {}
-			} catch (ClassNotFoundException cnfe2) {
+				m = Class.forName(className).getDeclaredMethod("getDecoder", boolean.class);
+				m.setAccessible(true);
+			} catch (NoSuchMethodException e) {
+				// Intentional fallthrough - getDecoder(boolean) is not always present.
+			} catch (ClassNotFoundException e) {
+				// Intentional fallthrough - getDecoder(boolean) is not always present.
 			}
+			return m;
 		}
-		compiler = c;
-		if (m != null) {
-			m.setAccessible(true);
-		}
-		decoderMethod = m;
+		
+		abstract JavaFileObject wrap(LombokFileObject fileObject);
+		abstract Method getDecoderMethod();
 	}
 	
 	private LombokFileObjects() {}
 	
-	static JavaFileObject createEmpty(String name, Kind kind) {
+	static Compiler getCompiler(JavaFileManager jfm) {
+		String jfmClassName = jfm != null ? jfm.getClass().getName() : "null";
+		if (jfmClassName.equals("com.sun.tools.javac.util.DefaultFileManager")) return Compiler.JAVAC6;
+		if (jfmClassName.equals("com.sun.tools.javac.file.JavacFileManager")) return Compiler.JAVAC7;
+		try {
+			if (Class.forName("com.sun.tools.javac.file.BaseFileObject") == null) throw new NullPointerException();
+			return Compiler.JAVAC7;
+		} catch (Exception e) {}
+		try {
+			if (Class.forName("com.sun.tools.javac.util.BaseFileObject") == null) throw new NullPointerException();
+			return Compiler.JAVAC6;
+		} catch (Exception e) {}
+		return null;
+	}
+	
+	static JavaFileObject createEmpty(Compiler compiler, String name, Kind kind) {
 		return compiler.wrap(new EmptyLombokFileObject(name, kind));
 	}
 	
-	static JavaFileObject createIntercepting(JavaFileObject delegate, String fileName, DiagnosticsReceiver diagnostics) {
-		return compiler.wrap(new InterceptingJavaFileObject(delegate, fileName, diagnostics, decoderMethod));
+	static JavaFileObject createIntercepting(Compiler compiler, JavaFileObject delegate, String fileName, DiagnosticsReceiver diagnostics) {
+		return compiler.wrap(new InterceptingJavaFileObject(delegate, fileName, diagnostics, compiler.getDecoderMethod()));
 	}
 }