Inline val: more correct and simple detection of write usages

#KT-17489 Fixed

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

@@ -18,7 +18,6 @@ package org.jetbrains.kotlin.idea.refactoring.inline
 
 import com.intellij.lang.findUsages.DescriptiveNameUtil
 import com.intellij.openapi.project.Project
-import com.intellij.psi.PsiElement
 import com.intellij.psi.search.GlobalSearchScope
 import com.intellij.psi.search.searches.ReferencesSearch
 import com.intellij.refactoring.BaseRefactoringProcessor
@@ -32,10 +31,7 @@ import org.jetbrains.kotlin.idea.codeInliner.replaceUsages
 import org.jetbrains.kotlin.idea.references.KtSimpleNameReference
 import org.jetbrains.kotlin.idea.stubindex.KotlinSourceFilterScope
 import org.jetbrains.kotlin.idea.util.application.runReadAction
-import org.jetbrains.kotlin.psi.KtCallableDeclaration
+import org.jetbrains.kotlin.psi.*
-import org.jetbrains.kotlin.psi.KtNamedFunction
-import org.jetbrains.kotlin.psi.KtProperty
-import org.jetbrains.kotlin.psi.KtSimpleNameExpression
 
 class KotlinInlineCallableProcessor(
         project: Project,
@@ -44,7 +40,7 @@ class KotlinInlineCallableProcessor(
         private val reference: KtSimpleNameReference?,
         private val inlineThisOnly: Boolean,
         private val deleteAfter: Boolean,
-        private val assignments: Set<PsiElement> = emptySet()
+        private val statementToDelete: KtBinaryExpression? = null
 ) : BaseRefactoringProcessor(project) {
 
     private val kind = when (declaration) {
@@ -71,11 +67,11 @@ class KotlinInlineCallableProcessor(
                 declaration,
                 myProject,
                 commandName,
-                {
+                postAction = {
                     if (deleteAfter) {
                         if (usages.size == simpleNameUsages.size) {
                             declaration.delete()
-                            assignments.forEach(PsiElement::delete)
+                            statementToDelete?.delete()
                         }
                         else {
                             CommonRefactoringUtil.showErrorHint(

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

@@ -17,18 +17,18 @@
 package org.jetbrains.kotlin.idea.refactoring.inline
 
 import com.intellij.openapi.util.text.StringUtil
-import com.intellij.psi.PsiElement
 import com.intellij.refactoring.JavaRefactoringSettings
 import com.intellij.refactoring.inline.InlineOptionsDialog
 import org.jetbrains.kotlin.idea.codeInliner.CallableUsageReplacementStrategy
 import org.jetbrains.kotlin.idea.references.KtSimpleNameReference
+import org.jetbrains.kotlin.psi.KtBinaryExpression
 import org.jetbrains.kotlin.psi.KtProperty
 
 class KotlinInlineValDialog(
         private val property: KtProperty,
         private val reference: KtSimpleNameReference?,
         private val replacementStrategy: CallableUsageReplacementStrategy,
-        private val assignments: Set<PsiElement>
+        private val assignmentToDelete: KtBinaryExpression?
  ) : InlineOptionsDialog(property.project, true, property) {
 
     private var occurrenceCount = initOccurrencesNumber(property)
@@ -69,7 +69,7 @@ class KotlinInlineValDialog(
                 KotlinInlineCallableProcessor(project, replacementStrategy, property, reference,
                                               inlineThisOnly = isInlineThisOnly,
                                               deleteAfter = !isInlineThisOnly && !isKeepTheDeclaration,
-                                              assignments = assignments)
+                                              statementToDelete = assignmentToDelete)
         )
 
         val settings = JavaRefactoringSettings.getInstance()

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

@@ -39,13 +39,18 @@ import org.jetbrains.kotlin.idea.codeInliner.CodeToInlineBuilder
 import org.jetbrains.kotlin.idea.core.copied
 import org.jetbrains.kotlin.idea.refactoring.checkConflictsInteractively
 import org.jetbrains.kotlin.idea.references.KtSimpleNameReference
+import org.jetbrains.kotlin.idea.references.ReferenceAccess
+import org.jetbrains.kotlin.idea.references.readWriteAccess
 import org.jetbrains.kotlin.idea.util.getResolutionScope
-import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.KtBinaryExpression
+import org.jetbrains.kotlin.psi.KtElement
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtProperty
 import org.jetbrains.kotlin.psi.psiUtil.getAssignmentByLHS
 import org.jetbrains.kotlin.psi.psiUtil.getQualifiedExpressionForSelectorOrThis
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.types.TypeUtils
-import org.jetbrains.kotlin.types.expressions.OperatorConventions
 import org.jetbrains.kotlin.utils.addIfNotNull
 
 class KotlinInlineValHandler : InlineActionHandler() {
@@ -82,28 +87,24 @@ class KotlinInlineValHandler : InlineActionHandler() {
             return showErrorHint(project, editor, "$kind '$name' is never used")
         }
 
-        val assignments = hashSetOf<PsiElement>()
+        val writeUsages = referenceExpressions.filter { it.readWriteAccess(useResolveForReadWrite = true) != ReferenceAccess.READ }
-        referenceExpressions.forEach { expression ->
+        
-            val parent = expression.parent
-
-            val assignment = expression.getAssignmentByLHS()
-            if (assignment != null) {
-                assignments.add(parent)
-            }
-
-            if (parent is KtUnaryExpression && OperatorConventions.INCREMENT_OPERATIONS.contains(parent.operationToken)) {
-                assignments.add(parent)
-            }
-        }
-
         val initializerInDeclaration = declaration.initializer
-        val initializer = if (initializerInDeclaration != null) {
+        val initializer: KtExpression
-            if (!assignments.isEmpty()) return reportAmbiguousAssignment(project, editor, name, assignments)
+        val assignment: KtBinaryExpression?
-            initializerInDeclaration
+        if (initializerInDeclaration != null) {
+            if (!writeUsages.isEmpty()) {
+                return reportAmbiguousAssignment(project, editor, name, writeUsages)
+            }
+            initializer = initializerInDeclaration
+            assignment = null
         }
         else {
-            (assignments.singleOrNull() as? KtBinaryExpression)?.right
+            assignment = writeUsages.singleOrNull()
-            ?: return reportAmbiguousAssignment(project, editor, name, assignments)
+                    ?.getAssignmentByLHS()
+                    ?.takeIf { it.operationToken == KtTokens.EQ }
+            initializer = assignment?.right
+                          ?: return reportAmbiguousAssignment(project, editor, name, writeUsages)
         }
 
         val referencesInOriginalFile = referenceExpressions.filter { it.containingFile == file }
@@ -133,7 +134,7 @@ class KotlinInlineValHandler : InlineActionHandler() {
             val replacement = replacementBuilder.prepareCodeToInline(initializerCopy, emptyList(), ::analyzeInitializerCopy)
             val replacementStrategy = CallableUsageReplacementStrategy(replacement)
 
-            val dialog = KotlinInlineValDialog(declaration, reference, replacementStrategy, assignments)
+            val dialog = KotlinInlineValDialog(declaration, reference, replacementStrategy, assignment)
 
             if (!ApplicationManager.getApplication().isUnitTestMode) {
                 dialog.show()
@@ -159,7 +160,7 @@ class KotlinInlineValHandler : InlineActionHandler() {
         }
     }
 
-    private fun reportAmbiguousAssignment(project: Project, editor: Editor?, name: String, assignments: Set<PsiElement>) {
+    private fun reportAmbiguousAssignment(project: Project, editor: Editor?, name: String, assignments: Collection<PsiElement>) {
         val key = if (assignments.isEmpty()) "variable.has.no.initializer" else "variable.has.no.dominating.definition"
         val message = RefactoringBundle.getCannotRefactorMessage(RefactoringBundle.message(key, name))
         showErrorHint(project, editor, message)

idea/testData/refactoring/inline/inlineVariableOrProperty/AppendToCollection.kt

@@ -0,0 +1,4 @@
+fun foo(list: MutableList<Int>) {
+    val <caret>list1 = list
+    list1 += 10
+}

idea/testData/refactoring/inline/inlineVariableOrProperty/AppendToCollection.kt.after

@@ -0,0 +1,3 @@
+fun foo(list: MutableList<Int>) {
+    list += 10
+}

idea/testData/refactoring/inline/inlineVariableOrProperty/property/KT17489.kt

@@ -0,0 +1,10 @@
+class Predicate(val x: Int) {
+    operator fun plusAssign(y: Int) {}
+
+    operator fun unaryMinus() = Predicate(-x)
+}
+
+fun test(p: Predicate) {
+    val <caret>x = -p
+    x += 42
+}

idea/testData/refactoring/inline/inlineVariableOrProperty/property/KT17489.kt.after

@@ -0,0 +1,9 @@
+class Predicate(val x: Int) {
+    operator fun plusAssign(y: Int) {}
+
+    operator fun unaryMinus() = Predicate(-x)
+}
+
+fun test(p: Predicate) {
+    -p += 42
+}

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

@@ -539,6 +539,12 @@ public class InlineTestGenerated extends AbstractInlineTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/refactoring/inline/inlineVariableOrProperty"), Pattern.compile("^(\\w+)\\.kt$"), TargetBackend.ANY, true);
         }
 
+        @TestMetadata("AppendToCollection.kt")
+        public void testAppendToCollection() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/refactoring/inline/inlineVariableOrProperty/AppendToCollection.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("Basic.kt")
         public void testBasic() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/refactoring/inline/inlineVariableOrProperty/Basic.kt");
@@ -1000,6 +1006,12 @@ public class InlineTestGenerated extends AbstractInlineTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("KT17489.kt")
+            public void testKT17489() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/testData/refactoring/inline/inlineVariableOrProperty/property/KT17489.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("keepImport.kt")
             public void testKeepImport() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/testData/refactoring/inline/inlineVariableOrProperty/property/keepImport.kt");