"Merge 'if's" intention: do not remove nested comments

#KT-33258 Fixed
#KT-39552 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/MergeIfsIntention.kt

@@ -6,8 +6,12 @@
 package org.jetbrains.kotlin.idea.intentions
 
 import com.intellij.openapi.editor.Editor
+import com.intellij.psi.PsiComment
 import org.jetbrains.kotlin.idea.KotlinBundle
+import org.jetbrains.kotlin.idea.inspections.findExistingEditor
 import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.allChildren
+import org.jetbrains.kotlin.psi.psiUtil.startOffset
 
 class MergeIfsIntention : SelfTargetingIntention<KtIfExpression>(KtIfExpression::class.java, KotlinBundle.lazyMessage("merge.if.s")) {
     override fun isApplicableTo(element: KtIfExpression, caretOffset: Int): Boolean {
@@ -33,6 +37,18 @@ class MergeIfsIntention : SelfTargetingIntention<KtIfExpression>(KtIfExpression:
 
             val factory = KtPsiFactory(element)
 
+            val comments = element.allChildren.filter { it is PsiComment }.toList() +
+                    (element.then as? KtBlockExpression)?.allChildren?.filter { it is PsiComment }?.toList().orEmpty()
+            if (comments.isNotEmpty()) {
+                val parent = element.parent
+                comments.forEach { comment ->
+                    parent.addBefore(comment, element)
+                    parent.addBefore(factory.createNewLine(), element)
+                    comment.delete()
+                }
+                element.findExistingEditor()?.caretModel?.moveToOffset(element.startOffset)
+            }
+
             condition.replace(factory.createExpressionByPattern("$0 && $1", condition, secondCondition))
             val newBody = element.then!!.replace(nestedBody)
 

idea/testData/intentions/mergeIfs/comments.kt.after

@@ -1,6 +1,8 @@
 fun foo() {
     // comment 1
-    <caret>if (/* comment 2 */ true && false /* comment 3 */) {
+    /* comment 2 */
+    /* comment 3 */
+    <caret>if (true && false) {
         // comment 4
         foo()
     }

idea/testData/intentions/mergeIfs/comments2.kt

@@ -0,0 +1,11 @@
+fun foo() {
+    // comment1
+    <caret>if (true) /* comment2 */ /* comment3 */ {
+        // comment4
+        // comment5
+        if (false) {
+        }
+        // comment6
+        // comment7
+    }
+}

idea/testData/intentions/mergeIfs/comments2.kt.after

@@ -0,0 +1,11 @@
+fun foo() {
+    // comment1
+    /* comment2 */
+    /* comment3 */
+    // comment4
+    // comment5
+    // comment6
+    // comment7
+    <caret>if (true && false) {
+    }
+}

idea/testData/intentions/mergeIfs/comments3.kt

@@ -0,0 +1,8 @@
+fun foo() {
+    // comment1
+    <caret>if (true)
+        // comment2
+        // comment3
+        if (false) {
+        }
+}

idea/testData/intentions/mergeIfs/comments3.kt.after

@@ -0,0 +1,7 @@
+fun foo() {
+    // comment1
+    // comment2
+    // comment3
+    <caret>if (true && false) {
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -12225,6 +12225,16 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             runTest("idea/testData/intentions/mergeIfs/comments.kt");
         }
 
+        @TestMetadata("comments2.kt")
+        public void testComments2() throws Exception {
+            runTest("idea/testData/intentions/mergeIfs/comments2.kt");
+        }
+
+        @TestMetadata("comments3.kt")
+        public void testComments3() throws Exception {
+            runTest("idea/testData/intentions/mergeIfs/comments3.kt");
+        }
+
         @TestMetadata("else1.kt")
         public void testElse1() throws Exception {
             runTest("idea/testData/intentions/mergeIfs/else1.kt");