Convert to expression body: insert new-line after = for long lines

idea/src/org/jetbrains/kotlin/idea/inspections/UseExpressionBodyInspection.kt

@@ -174,9 +174,21 @@ class UseExpressionBodyInspection(private val convertEmptyToUnit: Boolean) : Abs
 
         val commentSaver = CommentSaver(body)
 
-        declaration.addBefore(KtPsiFactory(declaration).createEQ(), body)
+        val factory = KtPsiFactory(declaration)
+        declaration.addBefore(factory.createEQ(), body)
         val newBody = body.replaced(value)
 
+        val editor = declaration.findExistingEditor()
+        if (editor != null) {
+            val startOffset = newBody.startOffset
+            val document = editor.document
+            val startLine = document.getLineNumber(startOffset)
+            val rightMargin = editor.settings.getRightMargin(editor.project)
+            if (document.getLineEndOffset(startLine) - document.getLineStartOffset(startLine) >= rightMargin) {
+                declaration.addBefore(factory.createNewLine(), newBody)
+            }
+        }
+
         commentSaver.restore(newBody)
 
         if (deleteTypeHandler != null && declaration is KtCallableDeclaration) {

idea/testData/inspectionsLocal/useExpressionBody/veryVeryLong.kt

@@ -0,0 +1,5 @@
+fun foo(s1: String, s2: String) = s1 + s2
+
+fun bar(): String {
+    <caret>return foo("gjahkrgkjuyrtetyuairytoiuyareoihuyitouy897304hkdjgnba", "uiyiuye987130423toiuywtuiyrwityriwyhw")
+}

idea/testData/inspectionsLocal/useExpressionBody/veryVeryLong.kt.after

@@ -0,0 +1,4 @@
+fun foo(s1: String, s2: String) = s1 + s2
+
+fun bar(): String =
+        foo("gjahkrgkjuyrtetyuairytoiuyareoihuyitouy897304hkdjgnba", "uiyiuye987130423toiuywtuiyrwityriwyhw")

idea/testData/refactoring/extractFunction/basic/callableReferenceSelector.kt.after

@@ -10,6 +10,7 @@ class Foo {
             arguments = map(arg)
         }
 
-        private fun map(arg: String) = mapOf(Foo::arguments.name to arg)
+        private fun map(arg: String) =
+                mapOf(Foo::arguments.name to arg)
     }
 }

idea/testData/refactoring/extractFunction/parameters/capturedFunctions/localExtensionFunChainedCalls.kt.after

@@ -13,4 +13,5 @@ fun foo(n: Int): Int {
     return i(n, Int::bar1, Int::bar2)
 }
 
-private fun i(n: Int, bar1: Int.(m: Int) -> Int, bar2: Int.(m: Int) -> Int) = n.bar1(n + 1).bar2(n + 2)
+private fun i(n: Int, bar1: Int.(m: Int) -> Int, bar2: Int.(m: Int) -> Int) =
+        n.bar1(n + 1).bar2(n + 2)

idea/testData/refactoring/extractFunction/typeParameters/typeParametersAndConstraintsCombined1.kt.after

@@ -17,4 +17,5 @@ class A<T: Data>(val t: T) where T: DataEx {
     }
 }
 
-private fun <T : Data, U : Data, V : Data> i(a: A<T>, b: A<T>.B<U>, v: V) where T : DataEx, U : DataExEx, V : DataEx = a.t.x + b.u.x + v.x
+private fun <T : Data, U : Data, V : Data> i(a: A<T>, b: A<T>.B<U>, v: V) where T : DataEx, U : DataExEx, V : DataEx =
+        a.t.x + b.u.x + v.x

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -863,6 +863,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("veryVeryLong.kt")
+        public void testVeryVeryLong() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/useExpressionBody/veryVeryLong.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("when.kt")
         public void testWhen() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/useExpressionBody/when.kt");