Fix for KT-12892 J2K: Wrong placing of comments when constructor converted to primary constructor & init

j2k/src/org/jetbrains/kotlin/j2k/ClassBodyConverter.kt

@@ -106,7 +106,7 @@ class ClassBodyConverter(private val psiClass: PsiClass,
                 }
             }
 
-            return ClassBody(null, null, convertedMembers.values.toList(), emptyList(), lBrace, rBrace, classKind)
+            return ClassBody(null, null, null, convertedMembers.values.toList(), emptyList(), lBrace, rBrace, classKind)
         }
 
         val useCompanionObject = shouldGenerateCompanionObject(convertedMembers)
@@ -114,11 +114,13 @@ class ClassBodyConverter(private val psiClass: PsiClass,
         val members = ArrayList<Member>()
         val companionObjectMembers = ArrayList<Member>()
         var primaryConstructorSignature: PrimaryConstructorSignature? = null
+        var primaryConstructor: PrimaryConstructor? = null
         for ((psiMember, member) in convertedMembers) {
             if (member is PrimaryConstructor) {
+                primaryConstructor = member
                 assert(primaryConstructorSignature == null)
-                primaryConstructorSignature = member.createSignature(converter)
+                primaryConstructorSignature = primaryConstructor.createSignature(converter)
-                members.add(member.initializer())
+                members.add(primaryConstructor.initializer)
             }
             else if (useCompanionObject && member !is Class && psiMember !is PsiEnumConstant && psiMember.hasModifierProperty(PsiModifier.STATIC)) {
                 companionObjectMembers.add(member)
@@ -131,7 +133,8 @@ class ClassBodyConverter(private val psiClass: PsiClass,
             }
         }
 
-        if (primaryConstructorSignature != null
+        if (primaryConstructor != null
+            && primaryConstructorSignature != null
             && classKind != ClassKind.ANONYMOUS_OBJECT
             && primaryConstructorSignature.annotations.isEmpty
             && primaryConstructorSignature.accessModifier == null
@@ -141,7 +144,7 @@ class ClassBodyConverter(private val psiClass: PsiClass,
             primaryConstructorSignature = null // no "()" after class name is needed in this case
         }
 
-        return ClassBody(primaryConstructorSignature, constructorConverter?.baseClassParams, members, companionObjectMembers, lBrace, rBrace, classKind)
+        return ClassBody(primaryConstructor, primaryConstructorSignature, constructorConverter?.baseClassParams, members, companionObjectMembers, lBrace, rBrace, classKind)
     }
 
     private fun convertMember(

j2k/src/org/jetbrains/kotlin/j2k/Converter.kt

@@ -175,7 +175,7 @@ class Converter private constructor(
         val implementsTypes = convertToNotNullableTypes(psiClass.implementsListTypes)
         val name = psiClass.declarationIdentifier()
 
-        return when {
+        val converted = when {
             psiClass.isInterface -> {
                 val classBody = ClassBodyConverter(psiClass, ClassKind.INTERFACE, this).convertBody()
                 Interface(name, annotations, modifiers, typeParameters, extendsTypes, implementsTypes, classBody)
@@ -208,6 +208,18 @@ class Converter private constructor(
                 }
             }
         }.assignPrototype(psiClass)
+
+        if (converted.body.primaryConstructorSignature == null)
+            addPostUnfoldDeferredElementsAction {
+                val primaryConstructor = converted.body.primaryConstructor
+                if (primaryConstructor != null) {
+                    if (primaryConstructor.initializer.isEmpty)
+                        converted.prototypes = converted.prototypes!! + primaryConstructor.prototypes!!
+                    else
+                        primaryConstructor.initializer.assignPrototypesFrom(primaryConstructor, CommentsAndSpacesInheritance.NO_SPACES)
+                }
+            }
+        return converted
     }
 
     fun needOpenModifier(psiClass: PsiClass): Boolean {
@@ -285,7 +297,7 @@ class Converter private constructor(
 
         // to convert fields and nested types - they are not allowed in Kotlin but we convert them and let user refactor code
         var classBody = ClassBodyConverter(psiClass, ClassKind.ANNOTATION_CLASS, this).convertBody()
-        classBody = ClassBody(constructorSignature, classBody.baseClassParams, classBody.members,
+        classBody = ClassBody(null, constructorSignature, classBody.baseClassParams, classBody.members,
                               classBody.companionObjectMembers, classBody.lBrace, classBody.rBrace, classBody.classKind)
 
         return Class(psiClass.declarationIdentifier(),

j2k/src/org/jetbrains/kotlin/j2k/ast/ClassBody.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.j2k.append
 abstract class Member(var annotations: Annotations, val modifiers: Modifiers) : Element()
 
 class ClassBody (
+        val primaryConstructor: PrimaryConstructor?,
         val primaryConstructorSignature: PrimaryConstructorSignature?,
         val baseClassParams: List<DeferredElement<Expression>>?,
         val members: List<Member>,

j2k/src/org/jetbrains/kotlin/j2k/ast/Constructors.kt

@@ -39,10 +39,12 @@ class PrimaryConstructor(
 
     override fun generateCode(builder: CodeBuilder) { throw IncorrectOperationException() }
 
-    fun initializer(): Initializer
+    // Should be lazy, to defer `assignPrototypesFrom(this,...)` a bit,
-            = Initializer(body!!, Modifiers.Empty).assignPrototypesFrom(this, CommentsAndSpacesInheritance(commentsBefore = false))
+    // cause when `PrimaryConstructor` created prototypes not yet assigned
+    val initializer: Initializer by
+    lazy { Initializer(body, Modifiers.Empty).assignPrototypesFrom(this, CommentsAndSpacesInheritance(commentsBefore = false)) }
 
-    fun createSignature(converter: Converter): PrimaryConstructorSignature {
+    fun createSignature(converter: Converter): PrimaryConstructorSignature? {
         val signature = PrimaryConstructorSignature(annotations, modifiers, parameterList)
 
         // assign prototypes later because we don't know yet whether the body is empty or not

j2k/testData/fileOrElement/comments/commentsForConstructors.java

@@ -26,4 +26,24 @@ class B {
     } // end of constructor body
 
     void foo(){}
+}
+
+class CtorComment {
+    public String myA;
+
+    /*
+     * The magic of comments
+     */
+    // single line magic comments
+    public CtorComment() {
+        myA = "a";
+    }
+}
+
+class CtorComment2 {
+    /*
+     * The magic of comments
+     */
+    // single line magic comments
+    public CtorComment() {}
 }

j2k/testData/fileOrElement/comments/commentsForConstructors.kt

@@ -18,4 +18,22 @@ internal class B// this constructor will disappear
 
     fun foo() {
     }
-}
+}
+
+internal class CtorComment {
+    var myA: String
+
+    /*
+     * The magic of comments
+     */
+    // single line magic comments
+    init {
+        myA = "a"
+    }
+}
+
+/*
+     * The magic of comments
+     */
+// single line magic comments
+internal class CtorComment2

j2k/testData/fileOrElement/docComments/primaryConstructorDoc.java

@@ -0,0 +1,18 @@
+class CtorComment {
+    public String myA;
+
+    /**
+     * This constructor is especially useful
+     */
+    public CtorComment() {
+        myA = "str";
+    }
+}
+
+class CtorComment2 {
+
+    /**
+     * This constructor is especially useful
+     */
+    public CtorComment() {}
+}

j2k/testData/fileOrElement/docComments/primaryConstructorDoc.kt

@@ -0,0 +1,15 @@
+internal class CtorComment {
+    var myA: String
+
+    /**
+     * This constructor is especially useful
+     */
+    init {
+        myA = "str"
+    }
+}
+
+/**
+ * This constructor is especially useful
+ */
+internal class CtorComment2

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterForWebDemoTestGenerated.java

@@ -1807,6 +1807,12 @@ public class JavaToKotlinConverterForWebDemoTestGenerated extends AbstractJavaTo
             doTest(fileName);
         }
 
+        @TestMetadata("primaryConstructorDoc.java")
+        public void testPrimaryConstructorDoc() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/docComments/primaryConstructorDoc.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("quoted.java")
         public void testQuoted() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/docComments/quoted.java");

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterSingleFileTestGenerated.java

@@ -1807,6 +1807,12 @@ public class JavaToKotlinConverterSingleFileTestGenerated extends AbstractJavaTo
             doTest(fileName);
         }
 
+        @TestMetadata("primaryConstructorDoc.java")
+        public void testPrimaryConstructorDoc() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/docComments/primaryConstructorDoc.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("quoted.java")
         public void testQuoted() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/docComments/quoted.java");