Support JDK27: end positions moved from EndPosTable to JCTree.endpos

JDK27 removed com.sun.tools.javac.tree.EndPosTable and stores end
positions directly on tree nodes (JDK-8372948). Lombok resolved that
class in a static initializer and rethrew on failure, so the processor
never initialized and every compilation on JDK27 failed.

- Javac: probe for EndPosTable; when absent, use the no-arg
  DiagnosticPosition.getEndPosition() and write JCTree.endpos directly
- CommentCatcher: skip setting genEndPos where the field no longer exists
- new java27 parser factory: JDK27 dropped the keepEndPositions
  parameter from JavacParser and ParserFactory.newParser
- DocCommentIntegrator: implement the new no-arg getEndPosition()
- PrettyPrinter: drop an unused reflective getEndPosition lookup that
  would fail class init on JDK27
- add an opt-in test.javac27 target

Fixes #4072

buildScripts/tests.ant.xml

@@ -167,6 +167,11 @@ This buildfile is part of projectlombok.org. It takes care of compiling and runn
 		<test.javacX version="26" />
 	</target>
 	
+	<!-- 27 is non-LTS, not yet released -->
+	<target name="test.javac27" depends="test.compile, test.formatter.compile" description="runs the tests on your default VM, using javac27 as underlying compiler">
+		<test.javacX version="27" />
+	</target>
+	
 	<target name="test.javacCurrent" depends="test.compile, test.formatter.compile" description="runs the tests on your default VM, using its javac as underlying compiler">
 		<echo>Running TestJavac on JVM${ant.java.version}, with the javac built into your VM distributon.</echo>
 		<junit haltonfailure="yes" fork="true" forkmode="once">

src/delombok/lombok/delombok/DocCommentIntegrator.java

@@ -152,6 +152,13 @@ public class DocCommentIntegrator {
 							return pos;
 						}
 						
+						@SuppressWarnings("unused") // As of JDK27 this is the only getEndPosition; EndPosTable is gone.
+						public int getEndPosition() {
+							int end = Javac.getTreeEndPos(node);
+							if (end > pos) return end;
+							return pos + docCommentContent_.length();
+						}
+						
 						@SuppressWarnings("unused") // We compile against very old versions of javac intentionally (to support old stuff), but this is the method for newer impls.
 						public int getEndPosition(EndPosTable endPosTable) {
 							int end = endPosTable == null ? 0 : endPosTable.getEndPos(node);

src/delombok/lombok/delombok/PrettyPrinter.java

@@ -86,7 +86,6 @@ import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
 import com.sun.tools.javac.tree.JCTree.JCWhileLoop;
 import com.sun.tools.javac.tree.JCTree.JCWildcard;
 import com.sun.tools.javac.tree.JCTree.TypeBoundKind;
-import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
 import com.sun.tools.javac.util.List;
 import com.sun.tools.javac.util.Name;
 import com.sun.tools.javac.util.Position;
@@ -1615,17 +1614,10 @@ public class PrettyPrinter extends JCTree.Visitor {
 		}
 	}
 	
-	private static final Method getExtendsClause, getEndPosition;
+	private static final Method getExtendsClause;
 	
 	static {
 		getExtendsClause = getMethod(JCClassDecl.class, "getExtendsClause", new Class<?>[0]);
-		
-		if (getJavaCompilerVersion() < 8) {
-			getEndPosition = getMethod(DiagnosticPosition.class, "getEndPosition", java.util.Map.class);
-		} else {
-			getEndPosition = getMethod(DiagnosticPosition.class, "getEndPosition", "com.sun.tools.javac.tree.EndPosTable");
-		}
-		Permit.setAccessible(getEndPosition);
 	}
 	
 	private static Method getMethod(Class<?> clazz, String name, Class<?>... paramTypes) {
@@ -1636,18 +1628,6 @@ public class PrettyPrinter extends JCTree.Visitor {
 		}
 	}
 	
-	private static Method getMethod(Class<?> clazz, String name, String... paramTypes) {
-		try {
-			Class<?>[] c = new Class[paramTypes.length];
-			for (int i = 0; i < paramTypes.length; i++) c[i] = Class.forName(paramTypes[i]);
-			return Permit.getMethod(clazz, name, c);
-		} catch (NoSuchMethodException e) {
-			throw sneakyThrow(e);
-		} catch (ClassNotFoundException e) {
-			throw sneakyThrow(e);
-		}
-	}
-	
 	public static JCTree getExtendsClause(JCClassDecl decl) {
 		return (JCTree) Permit.invokeSneaky(getExtendsClause, decl);
 	}

src/stubs/com/sun/tools/javac/parser/JavacParser.java

@@ -6,6 +6,7 @@ package com.sun.tools.javac.parser;
 import com.sun.tools.javac.tree.JCTree;
 
 public class JavacParser {
+	// Up to javac26 the last boolean is keepEndPositions; as of javac27 (JDK-8372948) it is parseModuleInfo.
 	protected JavacParser(ParserFactory fac, Lexer S, boolean keepDocComments, boolean keepLineMap, boolean keepEndPositions) {
 	}
 	

src/utils/lombok/javac/CommentCatcher.java

@@ -44,7 +44,8 @@ public class CommentCatcher {
 		setInCompiler(compiler, context);
 		
 		compiler.keepComments = true;
-		compiler.genEndPos = true;
+		// genEndPos no longer exists as of javac27.
+		if (!Javac.endPosStoredOnTree()) compiler.genEndPos = true;
 		
 		return new CommentCatcher(compiler);
 	}
@@ -105,6 +106,9 @@ public class CommentCatcher {
 				parserFactory = Class.forName("lombok.javac.java7.CommentCollectingParserFactory");
 			} else if (javaCompilerVersion == 8) {
 				parserFactory = Class.forName("lombok.javac.java8.CommentCollectingParserFactory");
+			} else if (Javac.endPosStoredOnTree()) {
+				// JDK-8372948 also reshaped JavacParser's constructors.
+				parserFactory = Class.forName("lombok.javac.java27.CommentCollectingParserFactory");
 			} else {
 				parserFactory = Class.forName("lombok.javac.java9.CommentCollectingParserFactory");
 			}

src/utils/lombok/javac/Javac.java

@@ -213,37 +213,51 @@ public class Javac {
 	
 	private static final Method getExtendsClause, getEndPosition, storeEnd;
 	
+	/** As of javac27 (JDK-8372948), end positions live in {@code JCTree.endpos} and {@code EndPosTable} no longer exists. */
+	private static final boolean ENDPOS_ON_TREE;
+	
 	static {
 		getExtendsClause = getMethod(JCClassDecl.class, "getExtendsClause", new Class<?>[0]);
 		
 		if (getJavaCompilerVersion() < 8) {
+			ENDPOS_ON_TREE = false;
 			getEndPosition = getMethod(DiagnosticPosition.class, "getEndPosition", java.util.Map.class);
 			storeEnd = getMethod(java.util.Map.class, "put", Object.class, Object.class);
 		} else {
-			getEndPosition = getMethod(DiagnosticPosition.class, "getEndPosition", "com.sun.tools.javac.tree.EndPosTable");
-			Method storeEndMethodTemp;
 			Class<?> endPosTable;
 			try {
 				endPosTable = Class.forName("com.sun.tools.javac.tree.EndPosTable");
 			} catch (ClassNotFoundException ex) {
-				throw sneakyThrow(ex);
+				endPosTable = null;
 			}
-			try {
-				storeEndMethodTemp = Permit.getMethod(endPosTable, "storeEnd", JCTree.class, int.class);
-			} catch (NoSuchMethodException e) {
+			ENDPOS_ON_TREE = endPosTable == null;
+			if (ENDPOS_ON_TREE) {
+				getEndPosition = getMethod(DiagnosticPosition.class, "getEndPosition", new Class<?>[0]);
+				storeEnd = null;
+			} else {
+				getEndPosition = getMethod(DiagnosticPosition.class, "getEndPosition", endPosTable);
+				Method storeEndMethodTemp;
 				try {
-					endPosTable = Class.forName("com.sun.tools.javac.parser.JavacParser$AbstractEndPosTable");
 					storeEndMethodTemp = Permit.getMethod(endPosTable, "storeEnd", JCTree.class, int.class);
-				} catch (NoSuchMethodException ex) {
-					throw sneakyThrow(ex);
-				} catch (ClassNotFoundException ex) {
-					throw sneakyThrow(ex);
+				} catch (NoSuchMethodException e) {
+					try {
+						endPosTable = Class.forName("com.sun.tools.javac.parser.JavacParser$AbstractEndPosTable");
+						storeEndMethodTemp = Permit.getMethod(endPosTable, "storeEnd", JCTree.class, int.class);
+					} catch (NoSuchMethodException ex) {
+						throw sneakyThrow(ex);
+					} catch (ClassNotFoundException ex) {
+						throw sneakyThrow(ex);
+					}
 				}
+				storeEnd = storeEndMethodTemp;
 			}
-			storeEnd = storeEndMethodTemp;
 		}
 		Permit.setAccessible(getEndPosition);
-		Permit.setAccessible(storeEnd);
+		if (storeEnd != null) Permit.setAccessible(storeEnd);
+	}
+	
+	static boolean endPosStoredOnTree() {
+		return ENDPOS_ON_TREE;
 	}
 	
 	private static Method getMethod(Class<?> clazz, String name, Class<?>... paramTypes) {
@@ -423,6 +437,7 @@ public class Javac {
 	
 	public static int getEndPosition(DiagnosticPosition pos, JCCompilationUnit top) {
 		try {
+			if (ENDPOS_ON_TREE) return (Integer) getEndPosition.invoke(pos);
 			Object endPositions = JCCOMPILATIONUNIT_ENDPOSITIONS.get(top);
 			return (Integer) getEndPosition.invoke(pos, endPositions);
 		} catch (IllegalAccessException e) {
@@ -432,8 +447,22 @@ public class Javac {
 		}
 	}
 
+	/** Returns -1 if this javac has no {@code JCTree.endpos} field (pre-27). */
+	public static int getTreeEndPos(JCTree tree) {
+		if (JCTREE_ENDPOS == null) return -1;
+		try {
+			return JCTREE_ENDPOS.getInt(tree);
+		} catch (IllegalAccessException e) {
+			throw sneakyThrow(e);
+		}
+	}
+	
 	public static void storeEnd(JCTree tree, int pos, JCCompilationUnit top) {
 		try {
+			if (ENDPOS_ON_TREE) {
+				if (JCTREE_ENDPOS != null) JCTREE_ENDPOS.setInt(tree, pos);
+				return;
+			}
 			Object endPositions = JCCOMPILATIONUNIT_ENDPOSITIONS.get(top);
 			if (endPositions == null) return;
 			storeEnd.invoke(endPositions, tree, pos);
@@ -513,6 +542,15 @@ public class Javac {
 		}
 	}
 	
+	private static final Field JCTREE_ENDPOS;
+	static {
+		Field f = null;
+		try {
+			f = Permit.getField(JCTree.class, "endpos");
+		} catch (NoSuchFieldException e) {}
+		JCTREE_ENDPOS = f;
+	}
+	
 	private static final Field JCCOMPILATIONUNIT_ENDPOSITIONS, JCCOMPILATIONUNIT_DOCCOMMENTS;
 	static {
 		Field f = null;

src/utils/lombok/javac/java27/CommentCollectingParser.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2026 The Project Lombok Authors.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package lombok.javac.java27;
+
+import static lombok.javac.CommentCatcher.JCCompilationUnit_comments;
+import static lombok.javac.CommentCatcher.JCCompilationUnit_textBlockStarts;
+
+import lombok.javac.java8.CommentCollectingScanner;
+
+import com.sun.tools.javac.parser.JavacParser;
+import com.sun.tools.javac.parser.Lexer;
+import com.sun.tools.javac.parser.ParserFactory;
+import com.sun.tools.javac.tree.JCTree.JCCompilationUnit;
+
+class CommentCollectingParser extends JavacParser {
+	private final Lexer lexer;
+	
+	// The stub constructor's last param is named keepEndPositions, but on javac27 this descriptor resolves to the constructor ending in parseModuleInfo.
+	protected CommentCollectingParser(ParserFactory fac, Lexer S,
+			boolean keepDocComments, boolean keepLineMap, boolean parseModuleInfo) {
+		super(fac, S, keepDocComments, keepLineMap, parseModuleInfo);
+		lexer = S;
+	}
+	
+	public JCCompilationUnit parseCompilationUnit() {
+		JCCompilationUnit result = super.parseCompilationUnit();
+		if (lexer instanceof CommentCollectingScanner) {
+			JCCompilationUnit_comments.set(result, ((CommentCollectingScanner) lexer).getComments());
+			JCCompilationUnit_textBlockStarts.set(result, ((CommentCollectingScanner) lexer).getTextBlockStarts());
+		}
+		return result;
+	}
+}

src/utils/lombok/javac/java27/CommentCollectingParserFactory.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2026 The Project Lombok Authors.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package lombok.javac.java27;
+
+import java.lang.reflect.Field;
+
+import com.sun.tools.javac.main.JavaCompiler;
+import com.sun.tools.javac.parser.JavacParser;
+import com.sun.tools.javac.parser.Lexer;
+import com.sun.tools.javac.parser.ParserFactory;
+import com.sun.tools.javac.parser.ScannerFactory;
+import com.sun.tools.javac.util.Context;
+
+import lombok.permit.Permit;
+
+public class CommentCollectingParserFactory extends ParserFactory {
+	private final Context context;
+	
+	static Context.Key<ParserFactory> key() {
+		return parserFactoryKey;
+	}
+	
+	protected CommentCollectingParserFactory(Context context) {
+		super(context);
+		this.context = context;
+	}
+	
+	public JavacParser newParser(CharSequence input, boolean keepDocComments, boolean keepLineMap, boolean parseModuleInfo) {
+		ScannerFactory scannerFactory = ScannerFactory.instance(context);
+		Lexer lexer = scannerFactory.newScanner(input, true);
+		Object x = new CommentCollectingParser(this, lexer, true, keepLineMap, parseModuleInfo);
+		return (JavacParser) x;
+		// CCP is based on a stub which extends nothing, but at runtime the stub is replaced with
+		//javac's JavacParser. Either way this will work out.
+	}
+	
+	public static void setInCompiler(JavaCompiler compiler, Context context) {
+		context.put(CommentCollectingParserFactory.key(), (ParserFactory) null);
+		Field field;
+		try {
+			field = Permit.getField(JavaCompiler.class, "parserFactory");
+			field.set(compiler, new CommentCollectingParserFactory(context));
+		} catch (Exception e) {
+			throw new IllegalStateException("Could not set comment sensitive parser in the compiler", e);
+		}
+	}
+}