Simplify and fix "recursive equals" inspection (related to KT-13702)

idea/src/org/jetbrains/kotlin/idea/inspections/RecursiveEqualsCallInspection.kt

@@ -21,16 +21,14 @@ import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiElementVisitor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.intentions.conventionNameCalls.isAnyEquals
 import org.jetbrains.kotlin.idea.search.usagesSearch.descriptor
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
-import org.jetbrains.kotlin.psi.psiUtil.containingClass
 import org.jetbrains.kotlin.psi.psiUtil.getNonStrictParentOfType
-import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
-import org.jetbrains.kotlin.types.typeUtil.isBoolean
-import org.jetbrains.kotlin.types.typeUtil.isNullableAny
+import org.jetbrains.kotlin.resolve.scopes.receivers.ThisClassReceiver
 
 class RecursiveEqualsCallInspection : AbstractKotlinInspection() {
     override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean, session: LocalInspectionToolSession): PsiElementVisitor {
@@ -38,18 +36,17 @@ class RecursiveEqualsCallInspection : AbstractKotlinInspection() {
 
             override fun visitBinaryExpression(expr: KtBinaryExpression) {
                 super.visitBinaryExpression(expr)
-
                 if (expr.operationToken != KtTokens.EQEQ) return
 
-                val classDescriptor = expr.containingClass()?.descriptor ?: return
                 val context = expr.analyze(BodyResolveMode.PARTIAL)
-                if (classDescriptor != expr.getResolvedCall(context)?.dispatchReceiver?.type?.constructor?.declarationDescriptor) return
+                val resolvedCall = expr.getResolvedCall(context)
+                val dispatchReceiver = resolvedCall?.dispatchReceiver as? ThisClassReceiver ?: return
+                val calledFunctionDescriptor = resolvedCall.resultingDescriptor as? FunctionDescriptor
+                if (calledFunctionDescriptor?.isAnyEquals() != true) return
 
-                val functionDescriptor = expr.getNonStrictParentOfType<KtNamedFunction>()?.descriptor as? FunctionDescriptor ?: return
-                if (functionDescriptor.name.asString() != "equals" ||
-                    !DescriptorUtils.isOverride(functionDescriptor) ||
-                    functionDescriptor.valueParameters.singleOrNull()?.type?.isNullableAny() == false ||
-                    functionDescriptor.returnType?.isBoolean() == false) return
+                val containingFunctionDescriptor = expr.getNonStrictParentOfType<KtNamedFunction>()?.descriptor as? FunctionDescriptor
+                if (calledFunctionDescriptor != containingFunctionDescriptor) return
+                if (dispatchReceiver.classDescriptor != containingFunctionDescriptor.containingDeclaration) return
 
                 holder.registerProblem(expr,
                                        "Recursive equals call",

idea/testData/inspectionsLocal/recursiveEqualsCall/recursiveFake.kt

@@ -0,0 +1,9 @@
+// PROBLEM: none
+
+class Test {
+    override fun equals(other: Any?): Boolean {
+        val another = Test()
+        if (<caret>another == other) return true
+        return false
+    }
+}

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

@@ -1513,6 +1513,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/recursiveEqualsCall/recursive.kt");
             doTest(fileName);
         }
+
+        @TestMetadata("recursiveFake.kt")
+        public void testRecursiveFake() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/recursiveEqualsCall/recursiveFake.kt");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("idea/testData/inspectionsLocal/redundantExplicitType")