Inline refactoring: fix case with introduction of variable to return

#KT-39818 Fixed

idea/src/org/jetbrains/kotlin/idea/codeInliner/CodeInliner.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -181,6 +181,7 @@ class CodeInliner<TCallElement : KtElement>(
             val usages = codeToInline.collectDescendantsOfType<KtExpression> {
                 it[CodeToInline.PARAMETER_USAGE_KEY] == parameterName
             }
+
             usages.forEach {
                 val usageArgument = it.parent as? KtValueArgument
                 if (argument.isNamed) {
@@ -189,7 +190,8 @@ class CodeInliner<TCallElement : KtElement>(
                 if (argument.isDefaultValue) {
                     usageArgument?.mark(DEFAULT_PARAMETER_VALUE_KEY)
                 }
-                codeToInline.replaceExpression(it, argument.expression)
+
+                codeToInline.replaceExpression(it, argument.expression.copied())
             }
 
             //TODO: sometimes we need to add explicit type arguments here because we don't have expected type in the new context

idea/src/org/jetbrains/kotlin/idea/codeInliner/MutableCodeToInline.kt

@@ -72,13 +72,7 @@ internal class MutableCodeToInline(
     val expressions: Collection<KtExpression>
         get() = statementsBefore + listOfNotNull(mainExpression)
 
-    operator fun contains(element: PsiElement): Boolean {
-        return expressions.any { it.isAncestor(element) }
-    }
-
-    fun containsStrictlyInside(element: PsiElement): Boolean {
-        return expressions.any { it.isAncestor(element, strict = true) }
-    }
+    operator fun contains(element: PsiElement): Boolean = expressions.any { it.isAncestor(element) }
 }
 
 internal fun CodeToInline.toMutable(): MutableCodeToInline {

idea/src/org/jetbrains/kotlin/idea/codeInliner/introduceValue.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.idea.codeInliner
@@ -57,7 +46,7 @@ internal fun MutableCodeToInline.introduceValue(
     nameSuggestion: String? = null,
     safeCall: Boolean = false
 ) {
-    assert(usages.all { this.containsStrictlyInside(it) })
+    assert(usages.all { it in this })
 
     val psiFactory = KtPsiFactory(value)
 
@@ -68,7 +57,7 @@ internal fun MutableCodeToInline.introduceValue(
         for (usage in usages) {
             // there can be parenthesis around the expression which will become unnecessary
             val usageToReplace = (usage.parent as? KtParenthesizedExpression) ?: usage
-            usageToReplace.replace(nameInCode)
+            replaceExpression(usageToReplace, nameInCode)
         }
     }
 

idea/src/org/jetbrains/kotlin/idea/refactoring/inline/inlineUtils.kt

@@ -166,7 +166,7 @@ internal fun buildCodeToInline(
         }
 
         return builder.prepareCodeToInline(
-            lastReturn?.returnedExpression,
+            lastReturn?.returnedExpression?.copied(),
             statements.dropLast(returnStatements.size), ::analyzeExpressionInContext, reformat = true
         )
     } else {

idea/testData/refactoring/inline/function/Kt39818.kt

@@ -0,0 +1,10 @@
+fun downUnder(): Int = 4
+fun downParameter<caret>(p: Int): Int {
+    "first $p"
+    "second $p"
+    p
+    return p
+}
+fun callDown() {
+    val result = downParameter(downUnder())
+}

idea/testData/refactoring/inline/function/Kt39818.kt.after

@@ -0,0 +1,8 @@
+fun downUnder(): Int = 4
+fun callDown() {
+    val p = downUnder()
+    "first ${p}"
+    "second ${p}"
+    p
+    val result = p
+}

idea/tests/org/jetbrains/kotlin/idea/refactoring/inline/InlineTestGenerated.java

@@ -65,6 +65,11 @@ public class InlineTestGenerated extends AbstractInlineTest {
             runTest("idea/testData/refactoring/inline/function/Kt30131.kt");
         }
 
+        @TestMetadata("Kt39818.kt")
+        public void testKt39818() throws Exception {
+            runTest("idea/testData/refactoring/inline/function/Kt39818.kt");
+        }
+
         @TestMetadata("LocalCapturing.kt")
         public void testLocalCapturing() throws Exception {
             runTest("idea/testData/refactoring/inline/function/LocalCapturing.kt");