Reflection: add utilities to filter parameters by kind and name

compiler/testData/codegen/box/reflection/parameters/findParameterByName.kt

@@ -0,0 +1,24 @@
+// WITH_REFLECT
+// FILE: J.java
+
+public class J {
+    public void bar(int x) {}
+}
+
+// FILE: K.kt
+
+import kotlin.reflect.findParameterByName
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+fun foo(x: Int) = x
+
+fun box(): String {
+    assertEquals(::foo.parameters.single(), ::foo.findParameterByName("x"))
+    assertNull(::foo.findParameterByName("y"))
+
+    assertNull(J::bar.findParameterByName("x"))
+    assertNull(J::bar.findParameterByName("y"))
+
+    return "OK"
+}

compiler/testData/codegen/box/reflection/parameters/instanceExtensionReceiverAndValueParameters.kt

@@ -0,0 +1,36 @@
+// WITH_REFLECT
+
+import kotlin.reflect.*
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+
+class A {
+    fun String.memExt(param: Int) {}
+}
+
+fun topLevel() {}
+
+fun Int.ext(vararg o: Any) {}
+
+fun box(): String {
+    A::class.members.single { it.name == "memExt" }.let {
+        assertNotNull(it.instanceParameter)
+        assertNotNull(it.extensionReceiverParameter)
+        assertEquals(1, it.valueParameters.size)
+    }
+
+    ::topLevel.let {
+        assertNull(it.instanceParameter)
+        assertNull(it.extensionReceiverParameter)
+        assertEquals(0, it.valueParameters.size)
+    }
+
+    Int::ext.let {
+        assertNull(it.instanceParameter)
+        assertNotNull(it.extensionReceiverParameter)
+        assertEquals(1, it.valueParameters.size)
+    }
+
+    return "OK"
+}

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

@@ -12789,12 +12789,24 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/reflection/parameters"), Pattern.compile("^(.+)\\.kt$"), true);
             }
 
+            @TestMetadata("findParameterByName.kt")
+            public void testFindParameterByName() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/parameters/findParameterByName.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("functionParameterNameAndIndex.kt")
             public void testFunctionParameterNameAndIndex() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/parameters/functionParameterNameAndIndex.kt");
                 doTest(fileName);
             }
 
+            @TestMetadata("instanceExtensionReceiverAndValueParameters.kt")
+            public void testInstanceExtensionReceiverAndValueParameters() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/parameters/instanceExtensionReceiverAndValueParameters.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("isMarkedNullable.kt")
             public void testIsMarkedNullable() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/parameters/isMarkedNullable.kt");

core/reflection.jvm/src/kotlin/reflect/KCallables.kt

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@file:JvmName("KCallables")
+package kotlin.reflect
+
+/**
+ * Returns a parameter representing the `this` instance needed to call this callable,
+ * or `null` if this callable is not a member of a class and thus doesn't take such parameter.
+ */
+val KCallable<*>.instanceParameter: KParameter?
+    get() = parameters.singleOrNull { it.kind == KParameter.Kind.INSTANCE }
+
+/**
+ * Returns a parameter representing the extension receiver instance needed to call this callable,
+ * or `null` if this callable is not an extension.
+ */
+val KCallable<*>.extensionReceiverParameter: KParameter?
+    get() = parameters.singleOrNull { it.kind == KParameter.Kind.EXTENSION_RECEIVER }
+
+/**
+ * Returns parameters of this callable, excluding the `this` instance and the extension receiver parameter.
+ */
+val KCallable<*>.valueParameters: List<KParameter>
+    get() = parameters.filter { it.kind == KParameter.Kind.VALUE }
+
+/**
+ * Returns the parameter of this callable with the given name, or `null` if there's no such parameter.
+ */
+fun KCallable<*>.findParameterByName(name: String): KParameter? {
+    return parameters.singleOrNull { it.name == name }
+}