Hiding default constructor with respect to its access modifiers

src/org/jetbrains/java/decompiler/main/ClassWriter.java

@@ -820,7 +820,7 @@ public class ClassWriter {
             BytecodeMappingTracer codeTracer = new BytecodeMappingTracer(tracer.getCurrentSourceLine());
             TextBuffer code = root.toJava(indent + 1, codeTracer);
 
-            hideMethod = (clinit || dinit || hideConstructor(wrapper, init, throwsExceptions, paramCount)) && code.length() == 0;
+            hideMethod = (code.length() == 0) && (clinit || dinit || hideConstructor(node, init, throwsExceptions, paramCount, flags));
 
             buffer.append(code);
 
@@ -859,13 +859,25 @@ public class ClassWriter {
     return !hideMethod;
   }
 
-  private static boolean hideConstructor(ClassWrapper wrapper, boolean init, boolean throwsExceptions, int paramCount) {
+  private static boolean hideConstructor(ClassNode node, boolean init, boolean throwsExceptions, int paramCount, int methodAccessFlags) {
+
     if (!init || throwsExceptions || paramCount > 0 || !DecompilerContext.getOption(IFernflowerPreferences.HIDE_DEFAULT_CONSTRUCTOR)) {
       return false;
     }
 
+    ClassWrapper wrapper = node.getWrapper();
+	  StructClass cl = wrapper.getClassStruct();
+
+	  int classAccesFlags = node.type == ClassNode.CLASS_ROOT ? cl.getAccessFlags() : node.access;
+    boolean isEnum = cl.hasModifier(CodeConstants.ACC_ENUM) && DecompilerContext.getOption(IFernflowerPreferences.DECOMPILE_ENUM);
+
+    // default constructor requires same accessibility flags. Exception: enum constructor which is always private
+  	if(!isEnum && ((classAccesFlags & ACCESSIBILITY_FLAGS) != (methodAccessFlags & ACCESSIBILITY_FLAGS))) {
+  	  return false;
+  	}
+
     int count = 0;
-    for (StructMethod mt : wrapper.getClassStruct().getMethods()) {
+    for (StructMethod mt : cl.getMethods()) {
       if (CodeConstants.INIT_NAME.equals(mt.getName())) {
         if (++count > 1) {
           return false;
@@ -1031,6 +1043,8 @@ public class ClassWriter {
   private static final int FIELD_EXCLUDED = CodeConstants.ACC_PUBLIC | CodeConstants.ACC_STATIC | CodeConstants.ACC_FINAL;
   private static final int METHOD_EXCLUDED = CodeConstants.ACC_PUBLIC | CodeConstants.ACC_ABSTRACT;
 
+  private static final int ACCESSIBILITY_FLAGS = CodeConstants.ACC_PUBLIC | CodeConstants.ACC_PROTECTED | CodeConstants.ACC_PRIVATE;
+
   private static void appendModifiers(TextBuffer buffer, int flags, int allowed, boolean isInterface, int excluded) {
     flags &= allowed;
     if (!isInterface) excluded = 0;

test/org/jetbrains/java/decompiler/SingleClassesTest.java

@@ -108,6 +108,7 @@ public class SingleClassesTest {
   @Test public void testMissingConstructorCallGood() { doTest("pkg/TestMissingConstructorCallGood"); }
   @Test public void testMissingConstructorCallBad() { doTest("pkg/TestMissingConstructorCallBad"); }
   @Test public void testEmptyBlocks() { doTest("pkg/TestEmptyBlocks"); }
+  @Test public void testPrivateEmptyConstructor() { doTest("pkg/TestPrivateEmptyConstructor"); }
 
 
   // TODO: fix all below

testData/results/TestPrivateEmptyConstructor.dec

@@ -0,0 +1,26 @@
+public final class TestPrivateEmptyConstructor {
+   private TestPrivateEmptyConstructor() {
+   }// 4
+
+   public final void test() {
+      System.out.println("test");// 7
+   }// 8
+}
+
+class 'TestPrivateEmptyConstructor' {
+   method '<init> ()V' {
+      4      2
+   }
+
+   method 'test ()V' {
+      0      5
+      3      5
+      5      5
+      8      6
+   }
+}
+
+Lines mapping:
+4 <-> 3
+7 <-> 6
+8 <-> 7

testData/src/pkg/TestPrivateEmptyConstructor.java

@@ -0,0 +1,10 @@
+
+public final class PrivateEmptyConstructor {
+
+   private PrivateEmptyConstructor() {}
+
+   public final void test() {
+		System.out.println("test");
+   }
+}
+