fix: check for annotations before remove empty default constructor (s…

…kylot#1863)

.editorconfig

@@ -14,14 +14,14 @@ trim_trailing_whitespace = true
 [*.java]
 ij_java_continuation_indent_size = 8
 ij_java_use_single_class_imports = true
-ij_java_class_count_to_use_import_on_demand = 999
-ij_java_names_count_to_use_import_on_demand = 999
+ij_java_class_count_to_use_import_on_demand = 99
+ij_java_names_count_to_use_import_on_demand = 99
 ij_java_packages_to_use_import_on_demand = *
 
 [*.kt]
 ij_kotlin_continuation_indent_size = 8
-ij_kotlin_name_count_to_use_star_import = 999
-ij_kotlin_name_count_to_use_star_import_for_members = 999
+ij_kotlin_name_count_to_use_star_import = 99
+ij_kotlin_name_count_to_use_star_import_for_members = 99
 ij_kotlin_packages_to_use_import_on_demand = *
 
 [*.yml]

jadx-core/src/main/java/jadx/core/dex/visitors/ClassModifier.java

@@ -8,6 +8,7 @@
 import java.util.Objects;
 
 import jadx.api.plugins.input.data.AccessFlags;
+import jadx.api.plugins.input.data.attributes.JadxAttrType;
 import jadx.core.Consts;
 import jadx.core.dex.attributes.AFlag;
 import jadx.core.dex.attributes.AType;
@@ -306,19 +307,24 @@ private static boolean registersAndCastsOnly(InsnArg arg) {
 	 * Remove public empty constructors (static or default)
 	 */
 	private static void removeEmptyMethods(MethodNode mth) {
+		if (!mth.getArgRegs().isEmpty()) {
+			return;
+		}
 		AccessInfo af = mth.getAccessFlags();
-		boolean publicConstructor = af.isConstructor() && af.isPublic();
+		boolean publicConstructor = mth.isConstructor() && af.isPublic();
 		boolean clsInit = mth.getMethodInfo().isClassInit() && af.isStatic();
-		if ((publicConstructor || clsInit) && mth.getArgRegs().isEmpty()) {
-			List<BlockNode> bb = mth.getBasicBlocks();
-			if (bb == null || bb.isEmpty() || BlockUtils.isAllBlocksEmpty(bb)) {
-				if (clsInit) {
+		if (publicConstructor || clsInit) {
+			if (!BlockUtils.isAllBlocksEmpty(mth.getBasicBlocks())) {
+				return;
+			}
+			if (clsInit) {
+				mth.add(AFlag.DONT_GENERATE);
+			} else {
+				// don't remove default constructor if other constructors exists or constructor has annotations
+				if (mth.isDefaultConstructor()
+						&& !isNonDefaultConstructorExists(mth)
+						&& !mth.contains(JadxAttrType.ANNOTATION_LIST)) {
 					mth.add(AFlag.DONT_GENERATE);
-				} else {
-					// don't remove default constructor if other constructors exists
-					if (mth.isDefaultConstructor() && !isNonDefaultConstructorExists(mth)) {
-						mth.add(AFlag.DONT_GENERATE);
-					}
 				}
 			}
 		}

jadx-core/src/main/java/jadx/core/utils/BlockUtils.java

@@ -981,6 +981,9 @@ public static BlockNode skipSyntheticPredecessor(BlockNode block) {
 	}
 
 	public static boolean isAllBlocksEmpty(List<BlockNode> blocks) {
+		if (Utils.isEmpty(blocks)) {
+			return true;
+		}
 		for (BlockNode block : blocks) {
 			if (!block.getInstructions().isEmpty()) {
 				return false;

jadx-core/src/test/java/jadx/tests/integration/others/TestDefConstructorWithAnnotation.java

@@ -0,0 +1,33 @@
+package jadx.tests.integration.others;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.junit.jupiter.api.Test;
+
+import jadx.tests.api.IntegrationTest;
+
+import static jadx.tests.api.utils.assertj.JadxAssertions.assertThat;
+
+public class TestDefConstructorWithAnnotation extends IntegrationTest {
+
+	public static class TestCls {
+		@AnnotationTest
+		public TestCls() {
+		}
+
+		@Target(ElementType.CONSTRUCTOR)
+		@Retention(RetentionPolicy.RUNTIME)
+		public @interface AnnotationTest {
+		}
+	}
+
+	@Test
+	public void test() {
+		assertThat(getClassNode(TestCls.class))
+				.code()
+				.containsOne("@AnnotationTest");
+	}
+}