Add explicit this: fix false negative on variable call

^KT-39929 Fixed

Original commit: 277ceaaf669dc1dd9ee2c4997360f7c32671deb2

GitOrigin-RevId: 4e3fc1624eff48a2d39312b8c9de16a94444c4fe

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

@@ -10,12 +10,15 @@ import com.intellij.codeInspection.ProblemDescriptor
 import com.intellij.codeInspection.ProblemHighlightType
 import com.intellij.codeInspection.ProblemsHolder
 import com.intellij.openapi.project.Project
+import org.jetbrains.kotlin.descriptors.CallableDescriptor
+import org.jetbrains.kotlin.descriptors.ReceiverParameterDescriptor
 import org.jetbrains.kotlin.idea.KotlinBundle
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
-import org.jetbrains.kotlin.idea.intentions.getCallableDescriptor
 import org.jetbrains.kotlin.idea.util.getFactoryForImplicitReceiverWithSubtypeOf
 import org.jetbrains.kotlin.idea.util.getResolutionScope
 import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
+import org.jetbrains.kotlin.resolve.calls.model.VariableAsFunctionResolvedCall
 
 class ImplicitThisInspection : AbstractKotlinInspection() {
     override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean) = object : KtVisitorVoid() {
@@ -41,10 +44,10 @@ class ImplicitThisInspection : AbstractKotlinInspection() {
             val context = reference.analyze()
             val scope = reference.getResolutionScope(context) ?: return
 
-            val descriptor = reference.getCallableDescriptor() ?: return
-            val receiverDescriptor = descriptor.extensionReceiverParameter
-                ?: descriptor.dispatchReceiverParameter
-                ?: return
+            val resolvedCall = reference.getResolvedCall(context) ?: return
+            val variableDescriptor = (resolvedCall as? VariableAsFunctionResolvedCall)?.variableCall?.resultingDescriptor
+            val callableDescriptor = resolvedCall.resultingDescriptor
+            val receiverDescriptor = variableDescriptor?.receiverDescriptor() ?: callableDescriptor.receiverDescriptor() ?: return
             val receiverType = receiverDescriptor.type
 
             val expressionFactory = scope.getFactoryForImplicitReceiverWithSubtypeOf(receiverType) ?: return
@@ -59,6 +62,10 @@ class ImplicitThisInspection : AbstractKotlinInspection() {
             )
         }
 
+        private fun CallableDescriptor.receiverDescriptor(): ReceiverParameterDescriptor? {
+            return extensionReceiverParameter ?: dispatchReceiverParameter
+        }
+
         private fun KtExpression.isSelectorOfDotQualifiedExpression(): Boolean {
             val parent = parent
             return parent is KtDotQualifiedExpression && parent.selectorExpression == this

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

@@ -4885,6 +4885,16 @@ public abstract class LocalInspectionTestGenerated extends AbstractLocalInspecti
             runTest("testData/inspectionsLocal/implicitThis/already.kt");
         }
 
+        @TestMetadata("callVariableAsFunction.kt")
+        public void testCallVariableAsFunction() throws Exception {
+            runTest("testData/inspectionsLocal/implicitThis/callVariableAsFunction.kt");
+        }
+
+        @TestMetadata("callVariableAsFunction2.kt")
+        public void testCallVariableAsFunction2() throws Exception {
+            runTest("testData/inspectionsLocal/implicitThis/callVariableAsFunction2.kt");
+        }
+
         @TestMetadata("function.kt")
         public void testFunction() throws Exception {
             runTest("testData/inspectionsLocal/implicitThis/function.kt");

plugins/kotlin/idea/tests/testData/inspectionsLocal/implicitThis/callVariableAsFunction.kt

@@ -0,0 +1,11 @@
+class Foo {
+    operator fun invoke() {}
+}
+
+class Bar {
+    val foo = Foo()
+}
+
+fun Bar.test() {
+    <caret>foo()
+}

plugins/kotlin/idea/tests/testData/inspectionsLocal/implicitThis/callVariableAsFunction.kt.after

@@ -0,0 +1,11 @@
+class Foo {
+    operator fun invoke() {}
+}
+
+class Bar {
+    val foo = Foo()
+}
+
+fun Bar.test() {
+    this.foo()
+}

plugins/kotlin/idea/tests/testData/inspectionsLocal/implicitThis/callVariableAsFunction2.kt

@@ -0,0 +1,7 @@
+class Bar {
+    val bar: () -> Unit = {}
+}
+
+fun Bar.test() {
+    <caret>bar()
+}

plugins/kotlin/idea/tests/testData/inspectionsLocal/implicitThis/callVariableAsFunction2.kt.after

@@ -0,0 +1,7 @@
+class Bar {
+    val bar: () -> Unit = {}
+}
+
+fun Bar.test() {
+    this.bar()
+}