"Convert lambda to reference": do not remove required backticks

#KT-15700 Fixed

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

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.idea.util.IdeDescriptorRenderers
 import org.jetbrains.kotlin.idea.util.approximateFlexibleTypes
 import org.jetbrains.kotlin.idea.util.getResolutionScope
 import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.renderer.render
 import org.jetbrains.kotlin.resolve.BindingContext.FUNCTION
 import org.jetbrains.kotlin.resolve.BindingContext.REFERENCE_TARGET
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
@@ -229,8 +230,7 @@ open class ConvertLambdaToReferenceIntention(text: String) :
     companion object {
 
         private fun buildReferenceText(lambdaExpression: KtLambdaExpression, shortTypes: Boolean): String? {
-            val singleStatement = lambdaExpression.singleStatementOrNull()
-            return when (singleStatement) {
+            return when (val singleStatement = lambdaExpression.singleStatementOrNull()) {
                 is KtCallExpression -> {
                     val calleeReferenceExpression = singleStatement.calleeExpression as? KtNameReferenceExpression ?: return null
                     val resolvedCall = calleeReferenceExpression.resolveToCall() ?: return null
@@ -244,10 +244,9 @@ open class ConvertLambdaToReferenceIntention(text: String) :
                     "$receiverText::${singleStatement.getCallReferencedName()}"
                 }
                 is KtDotQualifiedExpression -> {
-                    val selector = singleStatement.selectorExpression
-                    val selectorReferenceName = when (selector) {
+                    val selectorReferenceName = when (val selector = singleStatement.selectorExpression) {
                         is KtCallExpression -> selector.getCallReferencedName() ?: return null
-                        is KtNameReferenceExpression -> selector.getReferencedName()
+                        is KtNameReferenceExpression -> selector.getSafeReferencedName()
                         else -> return null
                     }
                     val receiver = singleStatement.receiverExpression
@@ -278,7 +277,9 @@ open class ConvertLambdaToReferenceIntention(text: String) :
             }
         }
 
-        private fun KtCallExpression.getCallReferencedName() = (calleeExpression as? KtNameReferenceExpression)?.getReferencedName()
+        private fun KtCallExpression.getCallReferencedName() = (calleeExpression as? KtNameReferenceExpression)?.getSafeReferencedName()
+
+        private fun KtNameReferenceExpression.getSafeReferencedName() = getReferencedNameAsName().render()
 
         private fun KtLambdaExpression.singleStatementOrNull() = bodyExpression?.statements?.singleOrNull()
     }

idea/testData/intentions/convertLambdaToReference/backtickEscaped.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+fun `super`(x: Int): Int = TODO()
+
+fun main(args: Array<String>) {
+    listOf(1).map { <caret>`super`(it) }
+}

idea/testData/intentions/convertLambdaToReference/backtickEscaped.kt.after

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+fun `super`(x: Int): Int = TODO()
+
+fun main(args: Array<String>) {
+    listOf(1).map(::`super`)
+}

idea/testData/intentions/convertLambdaToReference/backtickEscaped2.kt

@@ -0,0 +1,3 @@
+class Person(val `super`: String)
+
+val reader = { p: Person -> p.`super`<caret> }

idea/testData/intentions/convertLambdaToReference/backtickEscaped2.kt.after

@@ -0,0 +1,3 @@
+class Person(val `super`: String)
+
+val reader = Person::`super`

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

@@ -4700,6 +4700,16 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             runTest("idea/testData/intentions/convertLambdaToReference/argumentWithReceiver.kt");
         }
 
+        @TestMetadata("backtickEscaped.kt")
+        public void testBacktickEscaped() throws Exception {
+            runTest("idea/testData/intentions/convertLambdaToReference/backtickEscaped.kt");
+        }
+
+        @TestMetadata("backtickEscaped2.kt")
+        public void testBacktickEscaped2() throws Exception {
+            runTest("idea/testData/intentions/convertLambdaToReference/backtickEscaped2.kt");
+        }
+
         @TestMetadata("classReference.kt")
         public void testClassReference() throws Exception {
             runTest("idea/testData/intentions/convertLambdaToReference/classReference.kt");