Reflection: add KAnnotatedElement.findAnnotation

#KT-12250 Fixed

compiler/testData/codegen/box/reflection/annotations/findAnnotation.kt

@@ -0,0 +1,15 @@
+// IGNORE_BACKEND: JS
+// WITH_REFLECT
+
+import kotlin.reflect.findAnnotation
+
+annotation class Yes(val value: String)
+annotation class No(val value: String)
+
+@Yes("OK")
+@No("Fail")
+class Foo
+
+fun box(): String {
+    return Foo::class.findAnnotation<Yes>()?.value ?: "Fail: no annotation"
+}

compiler/testData/codegen/light-analysis/reflection/annotations/findAnnotation.txt

@@ -0,0 +1,19 @@
+public final class FindAnnotationKt {
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+}
+
+@Yes
+@No
+public final class Foo {
+    public method <init>(): void
+}
+
+@java.lang.annotation.Retention
+public annotation class No {
+    public abstract method value(): java.lang.String
+}
+
+@java.lang.annotation.Retention
+public annotation class Yes {
+    public abstract method value(): java.lang.String
+}

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

@@ -12199,6 +12199,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 doTest(fileName);
             }
 
+            @TestMetadata("findAnnotation.kt")
+            public void testFindAnnotation() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/findAnnotation.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("propertyAccessors.kt")
             public void testPropertyAccessors() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/propertyAccessors.kt");

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

@@ -12199,6 +12199,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("findAnnotation.kt")
+            public void testFindAnnotation() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/findAnnotation.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("propertyAccessors.kt")
             public void testPropertyAccessors() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/propertyAccessors.kt");

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

@@ -12199,6 +12199,12 @@ public class LightAnalysisModeCodegenTestGenerated extends AbstractLightAnalysis
                 doTest(fileName);
             }
 
+            @TestMetadata("findAnnotation.kt")
+            public void testFindAnnotation() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/findAnnotation.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("propertyAccessors.kt")
             public void testPropertyAccessors() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/propertyAccessors.kt");

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

@@ -0,0 +1,25 @@
+/*
+ * 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("KAnnotatedElements")
+package kotlin.reflect
+
+/**
+ * Returns an annotation of the given type on this element.
+ */
+@Suppress("UNCHECKED_CAST")
+inline fun <reified T : Annotation> KAnnotatedElement.findAnnotation(): T? =
+        annotations.first { it is T } as T

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -14894,6 +14894,18 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                 throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
             }
 
+            @TestMetadata("findAnnotation.kt")
+            public void testFindAnnotation() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/findAnnotation.kt");
+                try {
+                    doTest(fileName);
+                }
+                catch (Throwable ignore) {
+                    return;
+                }
+                throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
+            }
+
             @TestMetadata("propertyAccessors.kt")
             public void testPropertyAccessors() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/annotations/propertyAccessors.kt");