Prepare for javac API changes to AST end positions

After the upcoming changes in https://bugs.openjdk.org/browse/JDK-8372948, end positions will be stored directly in each `JCTree`, and the separate `EndPosTable` map will no longer exist.

This change uses reflection to support both versions of the internal API, before and after the changes in JDK-8372948.

RELNOTES=n/a
PiperOrigin-RevId: 862702224

Author: cushon

src/main/java/com/google/testing/compile/Parser.java

@@ -63,7 +63,8 @@ static ParseResult parse(Iterable<? extends JavaFileObject> sources, String sour
       for (JavaFileObject source : sources) {
         log.useSource(source);
         JavacParser parser =
-            parserFactory.newParser(
+            newParser(
+                parserFactory,
                 source.getCharContent(false),
                 /* keepDocComments= */ true,
                 /* keepEndPos= */ true,
@@ -84,6 +85,31 @@ static ParseResult parse(Iterable<? extends JavaFileObject> sources, String sour
     }
   }
 
+  private static final boolean IS_END_POS_TABLE_PRESENT = getIsEndPosTablePresent();
+
+  private static boolean getIsEndPosTablePresent() {
+    try {
+      // JDK versions before https://bugs.openjdk.org/browse/JDK-8372948
+      Class.forName("com.sun.tools.javac.tree.EndPosTable");
+      return true;
+    } catch (ClassNotFoundException e) {
+      return false;
+    }
+  }
+
+  private static JavacParser newParser(
+      ParserFactory parserFactory,
+      CharSequence source,
+      boolean keepDocComments,
+      boolean keepEndPos,
+      boolean keepLineMap) {
+    if (IS_END_POS_TABLE_PRESENT) {
+      return parserFactory.newParser(source, keepDocComments, keepEndPos, keepLineMap);
+    }
+    return parserFactory.newParser(
+        source, keepDocComments, keepLineMap, /* parseModuleInfo */ false);
+  }
+
   /** Returns {@code true} if errors were found while parsing source files. */
   private static boolean foundParseErrors(List<Diagnostic<? extends JavaFileObject>> diagnostics) {
     return diagnostics.stream().anyMatch(d -> d.getKind().equals(ERROR));