Add formatting rule "new line between { and when entry"

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt

@@ -469,6 +469,10 @@ fun createSpacingBuilder(settings: CodeStyleSettings, builderUtil: KotlinSpacing
                 spacingForLeftBrace(block = parent.requireNode(), blockType = WHEN)
             }
 
+            inPosition(left = LBRACE, right = WHEN_ENTRY).customRule { _, _, _ ->
+                createSpacing(0, minLineFeeds = 1)
+            }
+
             val spacesInSimpleFunction = if (kotlinCustomSettings.INSERT_WHITESPACES_IN_SIMPLE_ONE_LINE_METHOD) 1 else 0
             inPosition(parent = FUNCTION_LITERAL,
                        left = LBRACE,

idea/src/org/jetbrains/kotlin/idea/quickfix/AddWhenRemainingBranchesFix.kt

@@ -27,7 +27,6 @@ import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.core.ShortenReferences
 import org.jetbrains.kotlin.idea.core.quoteIfNeeded
 import org.jetbrains.kotlin.idea.intentions.ImportAllMembersIntention
-import org.jetbrains.kotlin.idea.refactoring.isMultiLine
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getNonStrictParentOfType
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
@@ -80,10 +79,6 @@ class AddWhenRemainingBranchesFix(
             val elseBranch = element.entries.find { it.isElse }
             val psiFactory = KtPsiFactory(element)
 
-            if (missingCases.isNotEmpty() && !element.isMultiLine()) {
-                element.addBefore(psiFactory.createNewLine(), whenCloseBrace)
-            }
-
             for (case in missingCases) {
                 val branchConditionText = when (case) {
                     UnknownMissingCase, NullMissingCase, is BooleanMissingCase ->

idea/testData/formatter/WhenBraceAndEntry.after.kt

@@ -0,0 +1,5 @@
+fun foo(x: Int) = when (x) {
+    1 -> 2
+    3 -> 4
+    else -> 6
+}

idea/testData/formatter/WhenBraceAndEntry.kt

@@ -0,0 +1,4 @@
+fun foo(x: Int) = when(x) { 1 -> 2
+    3 -> 4
+    else -> 6
+}

idea/tests/org/jetbrains/kotlin/formatter/FormatterTestGenerated.java

@@ -746,6 +746,11 @@ public class FormatterTestGenerated extends AbstractFormatterTest {
             runTest("idea/testData/formatter/WhenBlockBlankLines.after.kt");
         }
 
+        @TestMetadata("WhenBraceAndEntry.after.kt")
+        public void testWhenBraceAndEntry() throws Exception {
+            runTest("idea/testData/formatter/WhenBraceAndEntry.after.kt");
+        }
+
         @TestMetadata("WhenComment.after.kt")
         public void testWhenComment() throws Exception {
             runTest("idea/testData/formatter/WhenComment.after.kt");