From b5f6eae5be2d24cd2403ac8a1c6d978b0d445daf Mon Sep 17 00:00:00 2001
From: Tim te Beek <tim@moderne.io>
Date: Sun, 6 Oct 2024 17:53:52 +0200
Subject: [PATCH] Use reflection to invoke getCommentTree to support Java 21 &
 23 (#4555)

* Use reflection to invoke getCommentTree to support Java 21 & 23

Fixes https://github.com/openrewrite/rewrite/issues/4540

* Catch new exceptions from Method invoke
---
 .../ReloadableJava21ParserVisitor.java        | 54 +++++++++++--------
 1 file changed, 33 insertions(+), 21 deletions(-)

diff --git a/rewrite-java-21/src/main/java/org/openrewrite/java/isolated/ReloadableJava21ParserVisitor.java b/rewrite-java-21/src/main/java/org/openrewrite/java/isolated/ReloadableJava21ParserVisitor.java
index 2c59e8f8924..016248562e1 100644
--- a/rewrite-java-21/src/main/java/org/openrewrite/java/isolated/ReloadableJava21ParserVisitor.java
+++ b/rewrite-java-21/src/main/java/org/openrewrite/java/isolated/ReloadableJava21ParserVisitor.java
@@ -44,6 +44,8 @@
 import javax.lang.model.element.Modifier;
 import javax.lang.model.element.Name;
 import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.nio.charset.Charset;
 import java.nio.file.Path;
 import java.util.*;
@@ -1664,32 +1666,42 @@ private <J2 extends J> J2 convert(Tree t) {
         try {
             String prefix = source.substring(cursor, max(((JCTree) t).getStartPosition(), cursor));
             cursor += prefix.length();
-            @SuppressWarnings("unchecked") J2 j = (J2) scan(t, formatWithCommentTree(prefix, (JCTree) t, docCommentTable.getCommentTree((JCTree) t)));
+            // Java 21 and 23 have a different return type from getCommentTree; with reflection we can support both
+            Method getCommentTreeMethod = DocCommentTable.class.getMethod("getCommentTree", JCTree.class);
+            DocCommentTree commentTree = (DocCommentTree) getCommentTreeMethod.invoke(docCommentTable, (JCTree) t);
+            @SuppressWarnings("unchecked") J2 j = (J2) scan(t, formatWithCommentTree(prefix, (JCTree) t, commentTree));
             return j;
+        } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException ex) {
+            reportJavaParsingException(ex);
+            throw new IllegalStateException("Failed to invoke getCommentTree method", ex);
         } catch (Throwable ex) {
-            // this SHOULD never happen, but is here simply as a diagnostic measure in the event of unexpected exceptions
-            StringBuilder message = new StringBuilder("Failed to convert for the following cursor stack:");
-            message.append("--- BEGIN PATH ---\n");
-
-            List<Tree> paths = stream(getCurrentPath().spliterator(), false).toList();
-            for (int i = paths.size(); i-- > 0; ) {
-                JCTree tree = (JCTree) paths.get(i);
-                if (tree instanceof JCCompilationUnit) {
-                    message.append("JCCompilationUnit(sourceFile = ").append(((JCCompilationUnit) tree).sourcefile.getName()).append(")\n");
-                } else if (tree instanceof JCClassDecl) {
-                    message.append("JCClassDecl(name = ").append(((JCClassDecl) tree).name).append(", line = ").append(lineNumber(tree)).append(")\n");
-                } else if (tree instanceof JCVariableDecl) {
-                    message.append("JCVariableDecl(name = ").append(((JCVariableDecl) tree).name).append(", line = ").append(lineNumber(tree)).append(")\n");
-                } else {
-                    message.append(tree.getClass().getSimpleName()).append("(line = ").append(lineNumber(tree)).append(")\n");
-                }
-            }
+            reportJavaParsingException(ex);
+            throw ex;
+        }
+    }
 
-            message.append("--- END PATH ---\n");
+    private void reportJavaParsingException(Throwable ex) {
+        // this SHOULD never happen, but is here simply as a diagnostic measure in the event of unexpected exceptions
+        StringBuilder message = new StringBuilder("Failed to convert for the following cursor stack:");
+        message.append("--- BEGIN PATH ---\n");
 
-            ctx.getOnError().accept(new JavaParsingException(message.toString(), ex));
-            throw ex;
+        List<Tree> paths = stream(getCurrentPath().spliterator(), false).toList();
+        for (int i = paths.size(); i-- > 0; ) {
+            JCTree tree = (JCTree) paths.get(i);
+            if (tree instanceof JCCompilationUnit) {
+                message.append("JCCompilationUnit(sourceFile = ").append(((JCCompilationUnit) tree).sourcefile.getName()).append(")\n");
+            } else if (tree instanceof JCClassDecl) {
+                message.append("JCClassDecl(name = ").append(((JCClassDecl) tree).name).append(", line = ").append(lineNumber(tree)).append(")\n");
+            } else if (tree instanceof JCVariableDecl) {
+                message.append("JCVariableDecl(name = ").append(((JCVariableDecl) tree).name).append(", line = ").append(lineNumber(tree)).append(")\n");
+            } else {
+                message.append(tree.getClass().getSimpleName()).append("(line = ").append(lineNumber(tree)).append(")\n");
+            }
         }
+
+        message.append("--- END PATH ---\n");
+
+        ctx.getOnError().accept(new JavaParsingException(message.toString(), ex));
     }
 
     private <J2 extends J> JRightPadded<J2> convert(Tree t, Function<Tree, Space> suffix) {