[kotlin] 'Redundant explicit this' inspection: fix false negative with overloaded extension functions of Int

^KTIJ-28762 Fixed

closes https://github.com/JetBrains/intellij-community/pull/2667

GitOrigin-RevId: d5f9122282ad1191011ad006821529913f4d6dd6

plugins/kotlin/idea/src/org/jetbrains/kotlin/idea/inspections/ExplicitThisInspection.kt

@@ -14,14 +14,15 @@ import org.jetbrains.kotlin.idea.base.resources.KotlinBundle
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.codeinsight.api.classic.inspections.AbstractKotlinInspection
 import org.jetbrains.kotlin.idea.inspections.ExplicitThisInspection.Util.thisAsReceiverOrNull
-import org.jetbrains.kotlin.idea.intentions.getCallableDescriptor
+import org.jetbrains.kotlin.idea.intentions.receiverType
 import org.jetbrains.kotlin.idea.util.*
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getChildOfType
 import org.jetbrains.kotlin.psi.psiUtil.referenceExpression
 import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.calls.util.getResolvedCall
 import org.jetbrains.kotlin.resolve.lazy.descriptors.LazyClassDescriptor
-import org.jetbrains.kotlin.synthetic.SyntheticJavaPropertyDescriptor
+import org.jetbrains.kotlin.resolve.scopes.utils.getImplicitReceiversHierarchy
 import org.jetbrains.kotlin.types.typeUtil.isSubtypeOf
 
 class ExplicitThisInspection : AbstractKotlinInspection() {
@@ -39,7 +40,7 @@ class ExplicitThisInspection : AbstractKotlinInspection() {
     }
 
     object Util {
-        fun KtExpression.thisAsReceiverOrNull() = when (this) {
+        fun KtExpression.thisAsReceiverOrNull(): KtThisExpression? = when (this) {
             is KtCallableReferenceExpression -> receiverExpression as? KtThisExpression
             is KtDotQualifiedExpression -> receiverExpression as? KtThisExpression
             else -> null
@@ -52,15 +53,14 @@ class ExplicitThisInspection : AbstractKotlinInspection() {
                 is KtDotQualifiedExpression -> expression.selectorExpression as? KtReferenceExpression
                 else -> null
             } ?: return false
-            val context = expression.analyze()
-            val scope = expression.getResolutionScope(context) ?: return false
-
             val referenceExpression = reference as? KtNameReferenceExpression ?: reference.getChildOfType() ?: return false
-            if (context.diagnostics.forElement(referenceExpression).any { it.factory == Errors.UNRESOLVED_REFERENCE }) return false
-            val receiverType = context[BindingContext.EXPRESSION_TYPE_INFO, thisExpression]?.type ?: return false
-            val referenceTarget = context[BindingContext.REFERENCE_TARGET, reference.referenceExpression()]
 
-            //we avoid overload-related problems by enforcing that there is only one candidate
+            val context = expression.analyze()
+            if (context.diagnostics.forElement(referenceExpression).any { it.factory == Errors.UNRESOLVED_REFERENCE }) return false
+            val scope = expression.getResolutionScope(context) ?: return false
+            val receiverType = context[BindingContext.EXPRESSION_TYPE_INFO, thisExpression]?.type ?: return false
+
+            val referenceTarget = context[BindingContext.REFERENCE_TARGET, reference.referenceExpression()]
             val name = referenceExpression.getReferencedNameAsName()
             val candidates = if (reference is KtCallExpression
                 || (expression is KtCallableReferenceExpression && referenceTarget is FunctionDescriptor)
@@ -70,16 +70,16 @@ class ExplicitThisInspection : AbstractKotlinInspection() {
             } else {
                 scope.getAllAccessibleVariables(name)
             }
-            if (referenceExpression.getCallableDescriptor() is SyntheticJavaPropertyDescriptor) {
-                if (candidates.map { it.containingDeclaration }.distinct().size != 1) return false
-            } else {
-                val candidate = candidates.singleOrNull() ?: return false
-                val extensionType = candidate.extensionReceiverParameter?.type
-                if (extensionType != null && extensionType != receiverType && receiverType.isSubtypeOf(extensionType)) return false
-            }
+            if (candidates.any { it.receiverType() == null }) return false
+
+            val implicitThis = reference.getResolutionScope(context)?.getImplicitReceiversHierarchy()?.firstOrNull() ?: return false
+            val explicitThis = thisExpression.getResolvedCall(context)?.resultingDescriptor ?: return false
+            val candidate = (if (implicitThis == explicitThis) candidates.firstOrNull() else candidates.singleOrNull()) ?: return false
+
+            val extensionType = candidate.extensionReceiverParameter?.type
+            if (extensionType != null && extensionType != receiverType && receiverType.isSubtypeOf(extensionType)) return false
 
             val expressionFactory = scope.getFactoryForImplicitReceiverWithSubtypeOf(receiverType) ?: return false
-
             val label = thisExpression.getLabelName() ?: ""
             return expressionFactory.matchesLabel(label)
         }

plugins/kotlin/idea/tests/test/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -5166,11 +5166,21 @@ public abstract class LocalInspectionTestGenerated extends AbstractLocalInspecti
             runTest("testData/inspectionsLocal/explicitThis/nestedReceiversExtensionDifferentParameters.kt");
         }
 
+        @TestMetadata("overloadedIntFunction.kt")
+        public void testOverloadedIntFunction() throws Exception {
+            runTest("testData/inspectionsLocal/explicitThis/overloadedIntFunction.kt");
+        }
+
         @TestMetadata("property.kt")
         public void testProperty() throws Exception {
             runTest("testData/inspectionsLocal/explicitThis/property.kt");
         }
 
+        @TestMetadata("propertyNamedCode.kt")
+        public void testPropertyNamedCode() throws Exception {
+            runTest("testData/inspectionsLocal/explicitThis/propertyNamedCode.kt");
+        }
+
         @TestMetadata("propertyReference.kt")
         public void testPropertyReference() throws Exception {
             runTest("testData/inspectionsLocal/explicitThis/propertyReference.kt");

plugins/kotlin/idea/tests/testData/inspectionsLocal/explicitThis/overloadedIntFunction.kt

@@ -0,0 +1,3 @@
+fun Int.foo(): Int {
+    return <caret>this.times(3)
+}

plugins/kotlin/idea/tests/testData/inspectionsLocal/explicitThis/overloadedIntFunction.kt.after

@@ -0,0 +1,3 @@
+fun Int.foo(): Int {
+    return times(3)
+}

plugins/kotlin/idea/tests/testData/inspectionsLocal/explicitThis/propertyNamedCode.kt

@@ -0,0 +1,5 @@
+class A(private var code: String) {
+    fun foo() {
+        <caret>this.code
+    }
+}

plugins/kotlin/idea/tests/testData/inspectionsLocal/explicitThis/propertyNamedCode.kt.after

@@ -0,0 +1,5 @@
+class A(private var code: String) {
+    fun foo() {
+        code
+    }
+}