Fix "Specify explicit lambda signature" when no parameters exists

So #KT-15075 Fixed

compiler/frontend/src/org/jetbrains/kotlin/psi/KtPsiFactory.kt

@@ -345,8 +345,10 @@ class KtPsiFactory @JvmOverloads constructor(private val project: Project, val m
 
     fun createTypeParameter(text: String) = createTypeParameterList("<$text>").parameters.first()!!
 
-    fun createLambdaParameterList(text: String) =
-            createLambdaExpression(text, "0").functionLiteral.valueParameterList!!
+    fun createLambdaParameterListIfAny(text: String) =
+            createLambdaExpression(text, "0").functionLiteral.valueParameterList
+
+    fun createLambdaParameterList(text: String) = createLambdaParameterListIfAny(text)!!
 
     fun createLambdaExpression(parameters: String, body: String): KtLambdaExpression =
             (if (parameters.isNotEmpty()) createExpression("{ $parameters -> $body }")

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

@@ -54,9 +54,9 @@ class SpecifyExplicitLambdaSignatureIntention : SelfTargetingIntention<KtLambdaE
                 .map { "${it.name}: ${IdeDescriptorRenderers.SOURCE_CODE.renderType(it.type)}" }
                 .joinToString(", ")
 
-        val newParameterList = psiFactory.createLambdaParameterList(parameterString)
+        val newParameterList = psiFactory.createLambdaParameterListIfAny(parameterString)
         val oldParameterList = functionLiteral.valueParameterList
-        if (oldParameterList != null) {
+        if (oldParameterList != null && newParameterList != null) {
             oldParameterList.replace(newParameterList)
         }
         else {
@@ -65,7 +65,7 @@ class SpecifyExplicitLambdaSignatureIntention : SelfTargetingIntention<KtLambdaE
             val addNewline = nextSibling is PsiWhiteSpace && nextSibling.text?.contains("\n") ?: false
             val (whitespace, arrow) = psiFactory.createWhitespaceAndArrow()
             functionLiteral.addRangeAfter(whitespace, arrow, openBraceElement)
-            functionLiteral.addAfter(newParameterList, openBraceElement)
+            newParameterList?.let { functionLiteral.addAfter(it, openBraceElement) }
             if (addNewline) {
                 functionLiteral.addAfter(psiFactory.createNewLine(), openBraceElement)
             }

idea/testData/intentions/specifyExplicitLambdaSignature/delegate.kt

@@ -0,0 +1,14 @@
+// IS_APPLICABLE: true
+// SKIP_ERRORS_BEFORE
+// ERROR: Modifier 'override' is not applicable to 'local function'
+// ERROR: Type mismatch: inferred type is () -> Unit but Base was expected
+
+// See also KT-15075
+
+interface Base {
+    fun foo()
+}
+
+class Derived : Base by <caret>{
+    override fun foo() {}
+}

idea/testData/intentions/specifyExplicitLambdaSignature/delegate.kt.after

@@ -0,0 +1,15 @@
+// IS_APPLICABLE: true
+// SKIP_ERRORS_BEFORE
+// ERROR: Modifier 'override' is not applicable to 'local function'
+// ERROR: Type mismatch: inferred type is () -> Unit but Base was expected
+
+// See also KT-15075
+
+interface Base {
+    fun foo()
+}
+
+class Derived : Base by {
+    ->
+    override fun foo() {}
+}

idea/testData/intentions/specifyExplicitLambdaSignature/noParameters.kt

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+
+fun bar() {}
+
+fun foo() {
+    run <caret>{
+        bar()
+    }
+}

idea/testData/intentions/specifyExplicitLambdaSignature/noParameters.kt.after

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+
+fun bar() {}
+
+fun foo() {
+    run {
+        ->
+        bar()
+    }
+}

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

@@ -14218,6 +14218,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("delegate.kt")
+        public void testDelegate() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/specifyExplicitLambdaSignature/delegate.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("emptyParamListWithBrackets.kt")
         public void testEmptyParamListWithBrackets() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/specifyExplicitLambdaSignature/emptyParamListWithBrackets.kt");
@@ -14266,6 +14272,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("noParameters.kt")
+        public void testNoParameters() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/specifyExplicitLambdaSignature/noParameters.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("shortenReferencesForParams.kt")
         public void testShortenReferencesForParams() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/specifyExplicitLambdaSignature/shortenReferencesForParams.kt");