MoveVariableDeclarationIntoWhenInspection shouldn't report a multi-line variable

#KT-30457 Fixed

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

@@ -13,6 +13,7 @@ import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElementVisitor
 import com.intellij.psi.SmartPsiElementPointer
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isOneLiner
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.countUsages
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.previousStatement
 import org.jetbrains.kotlin.psi.*
@@ -23,6 +24,8 @@ class MoveVariableDeclarationIntoWhenInspection : AbstractKotlinInspection(), Cl
         whenExpressionVisitor(fun(expression: KtWhenExpression) {
             val subjectExpression = expression.subjectExpression ?: return
             val property = expression.findDeclarationNear() ?: return
+            if (!property.isOneLiner()) return
+
             val action = property.action(expression)
             if (action == Action.NOTHING) return
 

idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableMultyLine.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+
+fun foo(): Int {
+    val a<caret> = if (true) true
+    else false
+
+    return when (a) {
+        true -> 42
+        else -> null
+    } ?: 55
+}

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

@@ -4525,6 +4525,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableInBinaryExpression.kt");
         }
 
+        @TestMetadata("notApplicableMultyLine.kt")
+        public void testNotApplicableMultyLine() throws Exception {
+            runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableMultyLine.kt");
+        }
+
         @TestMetadata("notApplicableOtherName.kt")
         public void testNotApplicableOtherName() throws Exception {
             runTest("idea/testData/inspectionsLocal/moveVariableDeclarationIntoWhen/notApplicableOtherName.kt");