Ignore changes to synthetic methods

.gitignore

@@ -13,4 +13,6 @@ bin
 # intellij
 out
 *.idea
-*.iml
+*.iml
+
+output.json

src/main/java/net/neoforged/jarcompatibilitychecker/core/ClassInfoComparer.java

@@ -15,6 +15,7 @@
 import net.neoforged.jarcompatibilitychecker.data.MemberInfo;
 import net.neoforged.jarcompatibilitychecker.data.MethodInfo;
 import net.neoforged.jarcompatibilitychecker.sort.TopologicalSort;
+import net.neoforged.jarcompatibilitychecker.util.AccessHelpers;
 import org.jetbrains.annotations.Nullable;
 import org.objectweb.asm.Opcodes;
 
@@ -111,6 +112,9 @@ public static ClassInfoComparisonResults compare(boolean checkBinary, @Nullable
  Set<MethodInfo> seenMethods = new HashSet<>();
 
  for (MethodInfo baseInfo : baseClassInfo.getMethods().values()) {
+ // base synthetic -> ignore changes
+ if (AccessHelpers.isSynthetic(baseInfo)) continue;
+
  boolean isStatic = (baseInfo.access & Opcodes.ACC_STATIC) != 0;
  MethodInfo inputInfo = getMethodInfo(concreteClassInfo, concreteParents, isStatic, baseInfo.name, baseInfo.desc);
  boolean methodInternal = isInternalApi(baseInfo, internalAnnotations, internalAnnotationCheckMode);
@@ -120,7 +124,8 @@ public static ClassInfoComparisonResults compare(boolean checkBinary, @Nullable
  boolean isMethodError = !methodInternal || internalAnnotationCheckMode == InternalAnnotationCheckMode.ERROR;
  boolean methodVisible = isVisible(checkBinary, baseInfo.access);
 
- if (inputInfo == null) {
+ // base non-synthetic -> synthetic should be considered an error as synthetic methods aren't stable
+ if (inputInfo == null || AccessHelpers.isSynthetic(inputInfo)) {
  if (checkBinary) {
  results.addMethodIncompatibility(baseInfo, IncompatibilityMessages.METHOD_REMOVED, isMethodError);
  } else if (methodVisible) {

src/main/java/net/neoforged/jarcompatibilitychecker/util/AccessHelpers.java

@@ -0,0 +1,14 @@
+package net.neoforged.jarcompatibilitychecker.util;
+
+import net.neoforged.jarcompatibilitychecker.data.MemberInfo;
+import org.objectweb.asm.Opcodes;
+
+public class AccessHelpers {
+ public static boolean isSynthetic(int access) {
+ return ((access & Opcodes.ACC_SYNTHETIC)) != 0;
+ }
+
+ public static boolean isSynthetic(MemberInfo info) {
+ return isSynthetic(info.getAccess());
+ }
+}

tests/base/src/main/java/com/example/test/TestClassA.java

@@ -7,6 +7,9 @@
 
 public class TestClassA {
  public String field;
+ public Runnable lambdaThing = () -> {
+ System.out.println("Hi!");
+ };
  public void publicMethodA(String p1) {
 
  }

tests/top/src/main/java/com/example/test/TestClassA.java

@@ -2,6 +2,7 @@
 
 abstract class TestClassA {
  public final String field = "a";
+ public Runnable lambdaThing;
  private void publicMethodA(String p1) {
 
  }