Do not rely on descriptors in KParameterImpl.equals/hashCode

For the same reason as in the previous commit: descriptors are cached
via weak references in moduleByClassLoader.kt and can be
garbage-collected at any point. So different instances of KParameterImpl
representing the same parameter may store different instances of
descriptors.

compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java

@@ -26167,6 +26167,11 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsHashCode.kt");
             }
 
+            @TestMetadata("parametersEqualsWithClearCaches.kt")
+            public void testParametersEqualsWithClearCaches() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsWithClearCaches.kt");
+            }
+
             @TestMetadata("parametersToString.kt")
             public void testParametersToString() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersToString.kt");

compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsWithClearCaches.kt

@@ -0,0 +1,46 @@
+// TARGET_BACKEND: JVM
+// WITH_REFLECT
+// FILE: box.kt
+
+import kotlin.reflect.KMutableProperty
+import kotlin.test.assertEquals
+
+inline fun check(message: String, generate: () -> Any?) {
+    val x1: Any?
+    val x2: Any?
+    try {
+        x1 = generate()
+
+        // Force clear the internal maps, as if the weak values in them are garbage-collected.
+        kotlin.reflect.jvm.internal.ReflectionFactoryImpl.clearCaches()
+
+        x2 = generate()
+    } catch (e: Throwable) {
+        throw AssertionError("Fail $message", e)
+    }
+
+    assertEquals(x1, x2, "Fail equals $message")
+    assertEquals(x2, x1, "Fail equals $message")
+    assertEquals(x1.hashCode(), x2.hashCode(), "Fail hashCode $message")
+}
+
+class C(c: Any) {
+    fun Any.a(a: Any): Any = a
+
+    var <X> X.x: X
+        get() = this
+        set(value) {}
+}
+
+fun box(): String {
+    check("constructor parameter") { C::class.constructors.single().parameters.single() }
+    check("instance parameter") { C::class.members.single { it.name == "a" }.parameters[0] }
+    check("value parameter") { C::class.members.single { it.name == "a" }.parameters[1] }
+
+    check("extension receiver parameter") { (C::class.members.single { it.name == "x" } as KMutableProperty<*>).parameters[1] }
+
+    // TODO: depends on KT-13490
+    // check("property setter parameter") { (C::class.members.single { it.name == "x" } as KMutableProperty<*>).setter.parameters[2] }
+
+    return "OK"
+}

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -27753,6 +27753,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsHashCode.kt");
             }
 
+            @TestMetadata("parametersEqualsWithClearCaches.kt")
+            public void testParametersEqualsWithClearCaches() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsWithClearCaches.kt");
+            }
+
             @TestMetadata("parametersToString.kt")
             public void testParametersToString() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersToString.kt");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -25387,6 +25387,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsHashCode.kt");
             }
 
+            @TestMetadata("parametersEqualsWithClearCaches.kt")
+            public void testParametersEqualsWithClearCaches() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsWithClearCaches.kt");
+            }
+
             @TestMetadata("parametersToString.kt")
             public void testParametersToString() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersToString.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -26167,6 +26167,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsHashCode.kt");
             }
 
+            @TestMetadata("parametersEqualsWithClearCaches.kt")
+            public void testParametersEqualsWithClearCaches() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsWithClearCaches.kt");
+            }
+
             @TestMetadata("parametersToString.kt")
             public void testParametersToString() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/methodsFromAny/parametersToString.kt");

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KParameterImpl.kt

@@ -64,10 +64,10 @@ internal class KParameterImpl(
         get() = descriptor.let { it is ValueParameterDescriptor && it.varargElementType != null }
 
     override fun equals(other: Any?) =
-        other is KParameterImpl && callable == other.callable && descriptor == other.descriptor
+        other is KParameterImpl && callable == other.callable && index == other.index
 
     override fun hashCode() =
-        (callable.hashCode() * 31) + descriptor.hashCode()
+        (callable.hashCode() * 31) + index.hashCode()
 
     override fun toString() =
         ReflectionObjectRenderer.renderParameter(this)