KT-11724 False suggestion to replace with compound assignment

#KT-11724 Fixed

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

@@ -20,14 +20,20 @@ import com.intellij.openapi.editor.Editor
 import com.intellij.psi.tree.IElementType
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.idea.analysis.analyzeInContext
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
 import org.jetbrains.kotlin.idea.inspections.IntentionBasedInspection
+import org.jetbrains.kotlin.idea.util.getResolutionScope
 import org.jetbrains.kotlin.idea.util.psi.patternMatching.matches
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.KtBinaryExpression
 import org.jetbrains.kotlin.psi.KtNameReferenceExpression
 import org.jetbrains.kotlin.psi.KtPsiFactory
+import org.jetbrains.kotlin.psi.doNotAnalyze
 import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.bindingContextUtil.getDataFlowInfo
+import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 
 class ReplaceWithOperatorAssignmentInspection : IntentionBasedInspection<KtBinaryExpression>(ReplaceWithOperatorAssignmentIntention())
 
@@ -38,12 +44,22 @@ class ReplaceWithOperatorAssignmentIntention : SelfTargetingOffsetIndependentInt
         val right = element.right as? KtBinaryExpression ?: return false
         if (right.left == null || right.right == null) return false
 
-        return checkExpressionRepeat(left, right)
+        val bindingContext = right.analyze(BodyResolveMode.PARTIAL)
+        if (!checkExpressionRepeat(left, right, bindingContext)) return false
+
+        // now check that the resulting operator assignment will be resolved
+        val opAssign = buildOperatorAssignment(element)
+        opAssign.getContainingKtFile().doNotAnalyze = null //TODO: strange hack
+        val resolutionScope = element.getResolutionScope(bindingContext, element.getResolutionFacade())
+        val newBindingContext = opAssign.analyzeInContext(resolutionScope,
+                                                          contextExpression = element,
+                                                          dataFlowInfo = bindingContext.getDataFlowInfo(element),
+                                                          isStatement = true)
+        return newBindingContext.diagnostics.forElement(opAssign.operationReference).isEmpty()
     }
 
-    private fun checkExpressionRepeat(variableExpression: KtNameReferenceExpression, expression: KtBinaryExpression): Boolean {
-        val context = expression.analyze()
-        val descriptor = context[BindingContext.REFERENCE_TARGET, expression.operationReference]?.containingDeclaration
+    private fun checkExpressionRepeat(variableExpression: KtNameReferenceExpression, expression: KtBinaryExpression, bindingContext: BindingContext): Boolean {
+        val descriptor = bindingContext[BindingContext.REFERENCE_TARGET, expression.operationReference]?.containingDeclaration
         val isPrimitiveOperation = descriptor is ClassDescriptor && KotlinBuiltIns.isPrimitiveType(descriptor.defaultType)
 
         val operationToken = expression.operationToken
@@ -62,7 +78,7 @@ class ReplaceWithOperatorAssignmentIntention : SelfTargetingOffsetIndependentInt
 
             expressionLeft is KtBinaryExpression -> {
                 val sameCommutativeOperation = expressionLeft.operationToken == operationToken && isCommutative(operationToken)
-                isPrimitiveOperation && sameCommutativeOperation && checkExpressionRepeat(variableExpression, expressionLeft)
+                isPrimitiveOperation && sameCommutativeOperation && checkExpressionRepeat(variableExpression, expressionLeft, bindingContext)
             }
 
             else -> {
@@ -79,12 +95,16 @@ class ReplaceWithOperatorAssignmentIntention : SelfTargetingOffsetIndependentInt
                                                                        operationToken == KtTokens.PERC
 
     override fun applyTo(element: KtBinaryExpression, editor: Editor?) {
+        element.replace(buildOperatorAssignment(element))
+    }
+
+    private fun buildOperatorAssignment(element: KtBinaryExpression): KtBinaryExpression {
         val replacement = buildOperatorAssignmentText(
                 element.left as KtNameReferenceExpression,
                 element.right as KtBinaryExpression,
                 ""
         )
-        element.replace(KtPsiFactory(element).createExpression(replacement))
+        return KtPsiFactory(element).createExpression(replacement) as KtBinaryExpression
     }
 
     tailrec private fun buildOperatorAssignmentText(variableExpression: KtNameReferenceExpression, expression: KtBinaryExpression, tail: String): String {

idea/testData/intentions/replaceWithOperatorAssignment/flexibleTypeBug.kt

@@ -0,0 +1,7 @@
+// IS_APPLICABLE: false
+// WITH_RUNTIME
+fun foo() {
+    var list1 = java.util.Collections.emptyList<String>()
+    val list2 = listOf("b")
+    list1 <caret>= list1 + list2
+}

idea/testData/intentions/replaceWithOperatorAssignment/plusAssignConflict.kt

@@ -0,0 +1,11 @@
+// IS_APPLICABLE: false
+class A
+
+operator fun A.plus(a: A): A = A()
+operator fun A.plusAssign(a: A){}
+
+fun foo() {
+    var a1 = A()
+    val a2 = A()
+    a1 <caret>= a1 + a2
+}

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

@@ -8137,6 +8137,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/intentions/replaceWithOperatorAssignment"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), true);
         }
 
+        @TestMetadata("flexibleTypeBug.kt")
+        public void testFlexibleTypeBug() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/replaceWithOperatorAssignment/flexibleTypeBug.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("illegalMultipleOperators.kt")
         public void testIllegalMultipleOperators() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/replaceWithOperatorAssignment/illegalMultipleOperators.kt");
@@ -8179,6 +8185,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("plusAssignConflict.kt")
+        public void testPlusAssignConflict() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/replaceWithOperatorAssignment/plusAssignConflict.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("rightSideRepeat.kt")
         public void testRightSideRepeat() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/replaceWithOperatorAssignment/rightSideRepeat.kt");