Rename UseExperimental->OptIn, Experimental->RequiresOptIn in compiler tests

compiler/testData/cli/jvm/experimentalAndUseExperimentalWithSameAnnotation.args

@@ -1,6 +1,6 @@
 $TESTDATA_DIR$/experimentalAndUseExperimentalWithSameAnnotation.kt
 -d
 $TEMP_DIR$
--Xuse-experimental=kotlin.Experimental
+-Xopt-in=kotlin.RequiresOptIn
 -Xexperimental=org.test.ExperimentalAPI
--Xuse-experimental=org.test.ExperimentalAPI
+-Xopt-in=org.test.ExperimentalAPI

compiler/testData/cli/jvm/experimentalAndUseExperimentalWithSameAnnotation.kt

@@ -1,4 +1,4 @@
 package org.test
 
-@Experimental
+@RequiresOptIn
 annotation class ExperimentalAPI

compiler/testData/cli/jvm/experimentalDeprecated.args

@@ -1,8 +1,8 @@
 $TESTDATA_DIR$/experimentalDeprecated.kt
 -d
 $TEMP_DIR$
--Xuse-experimental=kotlin.Experimental
+-Xopt-in=kotlin.RequiresOptIn
 -Xexperimental=org.test.Error1
 -Xexperimental=org.test.Hidden1
--Xuse-experimental=org.test.Error2
+-Xopt-in=org.test.Error2
--Xuse-experimental=org.test.Hidden2
+-Xopt-in=org.test.Hidden2

compiler/testData/cli/jvm/experimentalDeprecated.kt

@@ -1,17 +1,17 @@
 package org.test
 
 @Deprecated("Error1", level = DeprecationLevel.ERROR)
-@Experimental
+@RequiresOptIn
 annotation class Error1
 
 @Deprecated("Error2", level = DeprecationLevel.ERROR)
-@Experimental
+@RequiresOptIn
 annotation class Error2
 
 @Deprecated("Hidden1", level = DeprecationLevel.HIDDEN)
-@Experimental
+@RequiresOptIn
 annotation class Hidden1
 
 @Deprecated("Hidden2", level = DeprecationLevel.HIDDEN)
-@Experimental
+@RequiresOptIn
 annotation class Hidden2

compiler/testData/cli/jvm/experimentalDeprecatedWarning.args

@@ -1,6 +1,6 @@
 $TESTDATA_DIR$/experimentalDeprecatedWarning.kt
 -d
 $TEMP_DIR$
--Xuse-experimental=kotlin.Experimental
+-Xopt-in=kotlin.RequiresOptIn
--Xuse-experimental=org.test.Warning1
+-Xopt-in=org.test.Warning1
 -Xexperimental=org.test.Warning2

compiler/testData/cli/jvm/experimentalDeprecatedWarning.kt

@@ -1,9 +1,9 @@
 package org.test
 
 @Deprecated("Warning1", level = DeprecationLevel.WARNING)
-@Experimental
+@RequiresOptIn
 annotation class Warning1
 
 @Deprecated("Warning2", level = DeprecationLevel.WARNING)
-@Experimental
+@RequiresOptIn
 annotation class Warning2

compiler/testData/cli/jvm/experimentalIsNotAnnotation.args

@@ -2,4 +2,4 @@ $TESTDATA_DIR$/experimentalIsNotAnnotation.kt
 -d
 $TEMP_DIR$
 -Xexperimental=org.test.NotAnAnnotation1
--Xuse-experimental=org.test.NotAnAnnotation2
+-Xopt-in=org.test.NotAnAnnotation2

compiler/testData/cli/jvm/experimentalIsNotMarker.args

@@ -2,4 +2,4 @@ $TESTDATA_DIR$/experimentalIsNotMarker.kt
 -d
 $TEMP_DIR$
 -Xexperimental=org.test.NotAMarker1
--Xuse-experimental=org.test.NotAMarker2
+-Xopt-in=org.test.NotAMarker2

compiler/testData/cli/jvm/experimentalNested.args

@@ -1,5 +1,5 @@
 $TESTDATA_DIR$/experimentalNested.kt
 -d
 $TEMP_DIR$
--Xuse-experimental=kotlin.Experimental
+-Xopt-in=kotlin.RequiresOptIn
 -Xexperimental=org.test.Outer.Nested

compiler/testData/cli/jvm/experimentalNested.kt

@@ -1,7 +1,7 @@
 package org.test
 
 class Outer {
-    @Experimental
+    @RequiresOptIn
     annotation class Nested
 }
 

compiler/testData/cli/jvm/experimentalUnresolved.args

@@ -1,6 +1,6 @@
 $TESTDATA_DIR$/experimentalUnresolved.kt
 -d
 $TEMP_DIR$
--Xuse-experimental=org.test.Unresolved1
+-Xopt-in=org.test.Unresolved1
 -Xexperimental=org.test.Unresolved2
--Xuse-experimental=org.test.Unresolved3
+-Xopt-in=org.test.Unresolved3

compiler/testData/codegen/box/coroutines/asyncIteratorNullMerge_1_3.kt

@@ -20,7 +20,7 @@ interface AsyncIterator<out T> {
     operator suspend fun next(): T
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <T> asyncGenerate(@BuilderInference block: suspend AsyncGenerator<T>.() -> Unit): AsyncSequence<T> = object : AsyncSequence<T> {
     override fun iterator(): AsyncIterator<T> {
         val iterator = AsyncGeneratorIterator<T>()

compiler/testData/codegen/box/coroutines/asyncIteratorToList_1_3.kt

@@ -21,7 +21,7 @@ interface AsyncIterator<out T> {
     operator suspend fun next(): T
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <T> asyncGenerate(@BuilderInference block: suspend AsyncGenerator<T>.() -> Unit): AsyncSequence<T> = object : AsyncSequence<T> {
     override fun iterator(): AsyncIterator<T> {
         val iterator = AsyncGeneratorIterator<T>()

compiler/testData/codegen/box/coroutines/asyncIterator_1_3.kt

@@ -20,7 +20,7 @@ interface AsyncIterator<out T> {
     operator suspend fun next(): T
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <T> asyncGenerate(@BuilderInference block: suspend AsyncGenerator<T>.() -> Unit): AsyncSequence<T> = object : AsyncSequence<T> {
     override fun iterator(): AsyncIterator<T> {
         val iterator = AsyncGeneratorIterator<T>()

compiler/testData/codegen/box/coroutines/builderInferenceAndGenericArrayAcessCall.kt

@@ -8,7 +8,7 @@ interface Foo<T>
 
 class FooImpl<T> : Foo<T>
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <T> myflow(@BuilderInference block: Foo<T>.() -> Unit): Foo<T> {
     val impl = FooImpl<T>()
     impl.block()

compiler/testData/codegen/box/coroutines/kt30858.kt

@@ -16,7 +16,7 @@ fun myLaunch(
     block: suspend MyCoroutineScope.() -> Unit
 ) {}
 
-@UseExperimental(kotlin.experimental.ExperimentalTypeInference::class)
+@OptIn(kotlin.experimental.ExperimentalTypeInference::class)
 public fun <E> myProduce(@BuilderInference block: suspend MyProducerScope<E>.() -> Unit) {}
 
 fun <T> MyReceiveChannel<T>.debounce(period: Long) {

compiler/testData/codegen/box/coroutines/kt31784.kt

@@ -2,7 +2,7 @@
 // IGNORE_BACKEND_FIR: JVM_IR
 // WITH_RUNTIME
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 package test
 

compiler/testData/codegen/box/inference/builderInference.kt

@@ -22,7 +22,7 @@ interface LiveDataScope<T> {
     suspend fun emit(value: T)
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <T> liveData(@BuilderInference block: suspend LiveDataScope<T>.() -> Unit): LiveData<T> = null!!
 
 fun <Value> Flow<Value>.asLiveData() = liveData {

compiler/testData/codegen/bytecodeText/coroutines/debug/localVariableCorrectLabel.kt

@@ -10,7 +10,7 @@ fun main(args: Array<String>) {
     println(s.toList())
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 @BuilderInference
 suspend fun SequenceScope<Int>.awaitSeq(): Int = 42
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/callableReferenceToASuspendFunction.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +NewInference
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 import kotlin.reflect.KSuspendFunction0
 import kotlin.reflect.KSuspendFunction1

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/chainCallWithExtensionExplicitTypes.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +NewInference
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 import kotlin.experimental.ExperimentalTypeInference
 
@@ -12,7 +12,7 @@ interface ProducerScope<E> {
 class CoroutineScope
 class ReceiveChannel<E>
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 public fun <E> produce(@BuilderInference block: suspend ProducerScope<E>.() -> Unit): ProducerScope<E> = TODO()
 
 fun test(ls: List<Int>) =

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/chainCallWithExtensionExplicitTypes.txt

@@ -1,6 +1,6 @@
 package
 
-@kotlin.UseExperimental(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ E> produce(/*0*/ @kotlin.BuilderInference block: suspend ProducerScope<E>.() -> kotlin.Unit): ProducerScope<E>
+@kotlin.OptIn(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ E> produce(/*0*/ @kotlin.BuilderInference block: suspend ProducerScope<E>.() -> kotlin.Unit): ProducerScope<E>
 public fun test(/*0*/ ls: kotlin.collections.List<kotlin.Int>): ProducerScope<kotlin.Int>
 private fun </*0*/ E> kotlin.collections.Iterable<E>.asReceiveChannel(): ReceiveChannel<E>
 public suspend fun </*0*/ E, /*1*/ C> ReceiveChannel<E>.toChannel(/*0*/ destination: C): C

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/coroutineInferenceWithCapturedTypeVariable.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +NewInference
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 import kotlin.experimental.ExperimentalTypeInference
 
@@ -9,7 +9,7 @@ suspend fun main() {
 }
 
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <K> iFlow(@BuilderInference block: suspend iFlowCollector<in K>.() -> Unit): iFlow<K> = TODO()
 
 interface iFlowCollector<S> {

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/coroutineInferenceWithCapturedTypeVariable.txt

@@ -1,6 +1,6 @@
 package
 
-@kotlin.UseExperimental(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ K> iFlow(/*0*/ @kotlin.BuilderInference block: suspend iFlowCollector<in K>.() -> kotlin.Unit): iFlow<K>
+@kotlin.OptIn(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ K> iFlow(/*0*/ @kotlin.BuilderInference block: suspend iFlowCollector<in K>.() -> kotlin.Unit): iFlow<K>
 public suspend fun main(): kotlin.Unit
 
 public interface iFlow</*0*/ out V> {

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/correctMember.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/extensionPriority.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/extensionSuspend.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/extensionWithNonValuableConstraints.kt

@@ -1,9 +1,9 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !WITH_NEW_INFERENCE
 // NI_EXPECTED_FILE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/extensionsWithNonValuableConstraintsGenericBase.kt

@@ -1,9 +1,9 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !WITH_NEW_INFERENCE
 // NI_EXPECTED_FILE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/incorrectCalls.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 // !WITH_NEW_INFERENCE
 // NI_EXPECTED_FILE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/inferenceFromMethodInsideLocalVariable.kt

@@ -1,5 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 import kotlin.experimental.ExperimentalTypeInference
 
@@ -7,7 +7,7 @@ interface Inv<T> {
     fun send(e: T)
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <K> foo(@BuilderInference block: Inv<K>.() -> Unit) {}
 
 fun test(i: Int) {

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/inferenceFromMethodInsideLocalVariable.txt

@@ -1,6 +1,6 @@
 package
 
-@kotlin.UseExperimental(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ K> foo(/*0*/ @kotlin.BuilderInference block: Inv<K>.() -> kotlin.Unit): kotlin.Unit
+@kotlin.OptIn(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ K> foo(/*0*/ @kotlin.BuilderInference block: Inv<K>.() -> kotlin.Unit): kotlin.Unit
 public fun test(/*0*/ i: kotlin.Int): kotlin.Unit
 
 public interface Inv</*0*/ T> {

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/recursiveGenerators.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/recursiveGenerators2.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 // !WITH_NEW_INFERENCE
 // NI_EXPECTED_FILE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/returnTypeInference2.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/severalCandidatesWithDifferentVisibility.kt

@@ -1,4 +1,4 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
 
 // FILE: a.kt
@@ -19,7 +19,7 @@ public class Queue {
 
 // FILE: c.kt
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 package c
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/simpleGenerator.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/suspendCallsWithErrors.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 // !WITH_NEW_INFERENCE
 // NI_EXPECTED_FILE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/twoReceiversInScope.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/typeFromReceiver.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/variableCallInsideBuilderFunction.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +NewInference
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 import kotlin.experimental.ExperimentalTypeInference
 
@@ -8,7 +8,7 @@ interface ProducerScope<E> {
     fun yield(e: E)
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <E> produce(@BuilderInference block: ProducerScope<E>.() -> Unit): ProducerScope<E> = TODO()
 
 fun <K> filter(e: K, predicate: (K) -> Boolean) =

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/variableCallInsideBuilderFunction.txt

@@ -1,7 +1,7 @@
 package
 
 public fun </*0*/ K> filter(/*0*/ e: K, /*1*/ predicate: (K) -> kotlin.Boolean): ProducerScope<kotlin.Int>
-@kotlin.UseExperimental(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ E> produce(/*0*/ @kotlin.BuilderInference block: ProducerScope<E>.() -> kotlin.Unit): ProducerScope<E>
+@kotlin.OptIn(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ E> produce(/*0*/ @kotlin.BuilderInference block: ProducerScope<E>.() -> kotlin.Unit): ProducerScope<E>
 
 public interface ProducerScope</*0*/ E> {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/variableOfAFunctionTypeCall.kt

@@ -1,7 +1,7 @@
 // !USE_EXPERIMENTAL: kotlin.Experimental
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 
@@ -9,7 +9,7 @@ interface ProducerScope<E> {
     fun yield(e: E)
 }
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <E> produce(@BuilderInference block: ProducerScope<E>.() -> Unit): ProducerScope<E> = TODO()
 
 fun <K> filter(e: K, predicate: (K) -> Boolean) =

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/variableOfAFunctionTypeCall.txt

@@ -1,7 +1,7 @@
 package
 
 public fun </*0*/ K> filter(/*0*/ e: K, /*1*/ predicate: (K) -> kotlin.Boolean): ProducerScope<kotlin.Int>
-@kotlin.UseExperimental(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ E> produce(/*0*/ @kotlin.BuilderInference block: ProducerScope<E>.() -> kotlin.Unit): ProducerScope<E>
+@kotlin.OptIn(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ E> produce(/*0*/ @kotlin.BuilderInference block: ProducerScope<E>.() -> kotlin.Unit): ProducerScope<E>
 
 public interface ProducerScope</*0*/ E> {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/withParameter.kt

@@ -1,7 +1,7 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/kt28658.kt

@@ -1,5 +1,5 @@
 // !LANGUAGE: +NewInference
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
 
 import kotlin.experimental.ExperimentalTypeInference
@@ -18,7 +18,7 @@ class Foo<T>
 
 fun <T> f1(f: Foo<T>.() -> Unit) {}
 
-@UseExperimental(ExperimentalTypeInference::class)
+@OptIn(ExperimentalTypeInference::class)
 fun <T> f2(@BuilderInference f: Foo<T>.() -> Unit) {
 }
 

compiler/testData/diagnostics/testsWithStdLib/coroutines/kt28658.txt

@@ -1,7 +1,7 @@
 package
 
 public fun </*0*/ T> f1(/*0*/ f: Foo<T>.() -> kotlin.Unit): kotlin.Unit
-@kotlin.UseExperimental(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ T> f2(/*0*/ @kotlin.BuilderInference f: Foo<T>.() -> kotlin.Unit): kotlin.Unit
+@kotlin.OptIn(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ T> f2(/*0*/ @kotlin.BuilderInference f: Foo<T>.() -> kotlin.Unit): kotlin.Unit
 public fun test1(): kotlin.Unit
 public fun test2(): [ERROR : Error function type]
 public fun test3(): kotlin.Unit

compiler/testData/diagnostics/testsWithStdLib/coroutines/restrictSuspension/outerYield_1_3.kt

@@ -1,8 +1,8 @@
 // !LANGUAGE: +ReleaseCoroutines +ExperimentalBuilderInference
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // SKIP_TXT
 
-@file:UseExperimental(ExperimentalTypeInference::class)
+@file:OptIn(ExperimentalTypeInference::class)
 
 import kotlin.experimental.ExperimentalTypeInference
 

compiler/testData/diagnostics/testsWithStdLib/experimental/annotation.fir.kt

@@ -1,10 +1,10 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY, AnnotationTarget.TYPEALIAS,
         AnnotationTarget.VALUE_PARAMETER)
 annotation class ExperimentalAPI
@@ -65,41 +65,41 @@ package usage2
 
 import api.*
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno fun function() {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun parameter(@EAnno p: String) {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun parameterType(p: @EAnno String) {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun returnType(): @EAnno Unit {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno val property = ""
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno typealias Typealias = Unit
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno class Klass
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 annotation class AnnotationArgument(val p: EAnno)
 
 fun insideBody() {
-    @UseExperimental(ExperimentalAPI::class) @EAnno fun local() {}
+    @OptIn(ExperimentalAPI::class) @EAnno fun local() {}
 }
 
-fun inDefaultArgument(@UseExperimental(ExperimentalAPI::class) f: () -> Unit = @EAnno fun() {}) {}
+fun inDefaultArgument(@OptIn(ExperimentalAPI::class) f: () -> Unit = @EAnno fun() {}) {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 val inProperty = @EAnno fun() {}
 
 val inPropertyAccessor: () -> Unit
-    @UseExperimental(ExperimentalAPI::class)
+    @OptIn(ExperimentalAPI::class)
     get() = @EAnno fun() {}
 
 // FILE: usage-none.kt

compiler/testData/diagnostics/testsWithStdLib/experimental/annotation.kt

@@ -1,10 +1,10 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY, AnnotationTarget.TYPEALIAS,
         AnnotationTarget.VALUE_PARAMETER)
 annotation class ExperimentalAPI
@@ -65,41 +65,41 @@ package usage2
 
 import api.*
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno fun function() {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun parameter(@EAnno p: String) {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun parameterType(p: @EAnno String) {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun returnType(): @EAnno Unit {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno val property = ""
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno typealias Typealias = Unit
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 @EAnno class Klass
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 annotation class AnnotationArgument(val p: EAnno)
 
 fun insideBody() {
-    @UseExperimental(ExperimentalAPI::class) @EAnno fun local() {}
+    @OptIn(ExperimentalAPI::class) @EAnno fun local() {}
 }
 
-fun inDefaultArgument(@UseExperimental(ExperimentalAPI::class) f: () -> Unit = @EAnno fun() {}) {}
+fun inDefaultArgument(@OptIn(ExperimentalAPI::class) f: () -> Unit = @EAnno fun() {}) {}
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 val inProperty = @EAnno fun() {}
 
 val inPropertyAccessor: () -> Unit
-    @UseExperimental(ExperimentalAPI::class)
+    @OptIn(ExperimentalAPI::class)
     get() = @EAnno fun() {}
 
 // FILE: usage-none.kt

compiler/testData/diagnostics/testsWithStdLib/experimental/annotation.txt

@@ -9,7 +9,7 @@ package api {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.TYPE, AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY, AnnotationTarget.TYPEALIAS, AnnotationTarget.VALUE_PARAMETER}) public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.TYPE, AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY, AnnotationTarget.TYPEALIAS, AnnotationTarget.VALUE_PARAMETER}) public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
@@ -46,17 +46,17 @@ package usage1 {
 }
 
 package usage2 {
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public val inProperty: () -> kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public val inProperty: () -> kotlin.Unit
-    @get:kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public val inPropertyAccessor: () -> kotlin.Unit
+    @get:kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public val inPropertyAccessor: () -> kotlin.Unit
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public val property: kotlin.String = ""
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public val property: kotlin.String = ""
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public fun function(): kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public fun function(): kotlin.Unit
-    public fun inDefaultArgument(/*0*/ @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) f: () -> kotlin.Unit = ...): kotlin.Unit
+    public fun inDefaultArgument(/*0*/ @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) f: () -> kotlin.Unit = ...): kotlin.Unit
     public fun insideBody(): kotlin.Unit
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public fun parameter(/*0*/ @api.EAnno p: kotlin.String): kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public fun parameter(/*0*/ @api.EAnno p: kotlin.String): kotlin.Unit
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public fun parameterType(/*0*/ p: @api.EAnno kotlin.String): kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public fun parameterType(/*0*/ p: @api.EAnno kotlin.String): kotlin.Unit
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public fun returnType(): @api.EAnno kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public fun returnType(): @api.EAnno kotlin.Unit
 
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public final annotation class AnnotationArgument : kotlin.Annotation {
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public final annotation class AnnotationArgument : kotlin.Annotation {
         public constructor AnnotationArgument(/*0*/ p: api.EAnno)
         public final val p: api.EAnno
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
@@ -64,13 +64,13 @@ package usage2 {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public final class Klass {
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public final class Klass {
         public constructor Klass()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public typealias Typealias = kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) @api.EAnno public typealias Typealias = kotlin.Unit
 }
 
 package usage3 {

compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsages.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class ExperimentalAPI
 
 interface I
@@ -19,12 +19,12 @@ import api.*
 
 open class Base(val i: I)
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 class Derived : Base(Impl())
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 class Delegated : I by Impl()
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 val delegatedProperty by Impl()
 operator fun I.getValue(x: Any?, y: Any?) = null

compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsages.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class ExperimentalAPI
 
 interface I
@@ -19,12 +19,12 @@ import api.*
 
 open class Base(val i: I)
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 class Derived : Base(Impl())
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 class Delegated : I by Impl()
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 val delegatedProperty by Impl()
 operator fun I.getValue(x: Any?, y: Any?) = null

compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsages.txt

@@ -2,7 +2,7 @@ package
 
 package api {
 
-    @kotlin.Experimental(level = Level.WARNING) public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
@@ -24,7 +24,7 @@ package api {
 }
 
 package usage {
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public val delegatedProperty: kotlin.Nothing?
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public val delegatedProperty: kotlin.Nothing?
     public operator fun api.I.getValue(/*0*/ x: kotlin.Any?, /*1*/ y: kotlin.Any?): kotlin.Nothing?
 
     public open class Base {
@@ -35,14 +35,14 @@ package usage {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public final class Delegated : api.I {
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public final class Delegated : api.I {
         public constructor Delegated()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public final class Derived : usage.Base {
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public final class Derived : usage.Base {
         public constructor Derived()
         public final override /*1*/ /*fake_override*/ val i: api.I
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean

compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsagesAndInline.fir.kt

@@ -1,10 +1,10 @@
 // !DIAGNOSTICS: -NOTHING_TO_INLINE -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class API
 
 @API

compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsagesAndInline.kt

@@ -1,10 +1,10 @@
 // !DIAGNOSTICS: -NOTHING_TO_INLINE -UNUSED_PARAMETER
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class API
 
 @API

compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsagesAndInline.txt

@@ -3,7 +3,7 @@ package
 package api {
     @api.API public fun f(): kotlin.Unit
 
-    @kotlin.Experimental(level = Level.WARNING) public final annotation class API : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) public final annotation class API : kotlin.Annotation {
         public constructor API()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/classMembers.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
 annotation class ExperimentalAPI
 
@@ -51,7 +51,7 @@ package usage2
 
 import api.*
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun useAll() {
     val c: C = C()
     c.function()
@@ -61,7 +61,7 @@ fun useAll() {
     c.extension()
 }
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 class Use {
     fun useAll(c: C) {
         c.function()

compiler/testData/diagnostics/testsWithStdLib/experimental/classMembers.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
 annotation class ExperimentalAPI
 
@@ -51,7 +51,7 @@ package usage2
 
 import api.*
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun useAll() {
     val c: C = C()
     c.function()
@@ -61,7 +61,7 @@ fun useAll() {
     c.extension()
 }
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 class Use {
     fun useAll(c: C) {
         c.function()

compiler/testData/diagnostics/testsWithStdLib/experimental/classMembers.txt

@@ -26,7 +26,7 @@ package api {
         }
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.FUNCTION}) public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.FUNCTION}) public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
@@ -47,9 +47,9 @@ package usage1 {
 }
 
 package usage2 {
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public fun useAll(): kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public fun useAll(): kotlin.Unit
 
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public final class Use {
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public final class Use {
         public constructor Use()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/classMembersOverlyExperimental.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY)
 annotation class ExperimentalAPI
 

compiler/testData/diagnostics/testsWithStdLib/experimental/classMembersOverlyExperimental.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY)
 annotation class ExperimentalAPI
 

compiler/testData/diagnostics/testsWithStdLib/experimental/classMembersOverlyExperimental.txt

@@ -19,7 +19,7 @@ package api {
         }
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY}) public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY}) public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/constVal.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION)
 annotation class ExperimentalAPI
 
@@ -24,7 +24,7 @@ fun usage() {}
 
 // FILE: usage-use.kt
 
-@file:UseExperimental(ExperimentalAPI::class)
+@file:OptIn(ExperimentalAPI::class)
 package usage2
 
 import api.*

compiler/testData/diagnostics/testsWithStdLib/experimental/constVal.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION)
 annotation class ExperimentalAPI
 
@@ -24,7 +24,7 @@ fun usage() {}
 
 // FILE: usage-use.kt
 
-@file:UseExperimental(ExperimentalAPI::class)
+@file:OptIn(ExperimentalAPI::class)
 package usage2
 
 import api.*

compiler/testData/diagnostics/testsWithStdLib/experimental/constVal.txt

@@ -11,7 +11,7 @@ package api {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION}) public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION}) public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/deeplyNestedClass.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
 annotation class ExperimentalAPI
 
@@ -36,12 +36,12 @@ package usage2
 
 import api.*
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun use1() {
     C.D.E.F()
 }
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun use2(f: C.D.E.F) = f.hashCode()
 
 // FILE: usage-none.kt

compiler/testData/diagnostics/testsWithStdLib/experimental/deeplyNestedClass.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
 annotation class ExperimentalAPI
 
@@ -36,12 +36,12 @@ package usage2
 
 import api.*
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun use1() {
     C.D.E.F()
 }
 
-@UseExperimental(ExperimentalAPI::class)
+@OptIn(ExperimentalAPI::class)
 fun use2(f: C.D.E.F) = f.hashCode()
 
 // FILE: usage-none.kt

compiler/testData/diagnostics/testsWithStdLib/experimental/deeplyNestedClass.txt

@@ -30,7 +30,7 @@ package api {
         }
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.FUNCTION}) public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.FUNCTION}) public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
@@ -44,8 +44,8 @@ package usage1 {
 }
 
 package usage2 {
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public fun use1(): kotlin.Unit
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public fun use1(): kotlin.Unit
-    @kotlin.UseExperimental(markerClass = {api.ExperimentalAPI::class}) public fun use2(/*0*/ f: api.C.D.E.F): kotlin.Int
+    @kotlin.OptIn(markerClass = {api.ExperimentalAPI::class}) public fun use2(/*0*/ f: api.C.D.E.F): kotlin.Int
 }
 
 package usage3 {

compiler/testData/diagnostics/testsWithStdLib/experimental/errors.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental
+@RequiresOptIn
 annotation class E
 
 open class Base {

compiler/testData/diagnostics/testsWithStdLib/experimental/errors.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental
+@RequiresOptIn
 annotation class E
 
 open class Base {

compiler/testData/diagnostics/testsWithStdLib/experimental/errors.txt

@@ -10,7 +10,7 @@ package api {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.Experimental public final annotation class E : kotlin.Annotation {
+    @kotlin.RequiresOptIn public final annotation class E : kotlin.Annotation {
         public constructor E()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalIsNotEnabled.fir.kt

@@ -1,6 +1,6 @@
 // FILE: api.kt
 
-@Experimental
+@RequiresOptIn
 annotation class Marker
 
 @Marker
@@ -17,7 +17,7 @@ fun use2() {
     f()
 }
 
-@UseExperimental(Marker::class)
+@OptIn(Marker::class)
 fun use3() {
     f()
 }

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalIsNotEnabled.kt

@@ -1,6 +1,6 @@
 // FILE: api.kt
 
-@<!EXPERIMENTAL_IS_NOT_ENABLED!>Experimental<!>
+@<!EXPERIMENTAL_IS_NOT_ENABLED!>RequiresOptIn<!>
 annotation class Marker
 
 @Marker
@@ -17,7 +17,7 @@ fun use2() {
     f()
 }
 
-@<!EXPERIMENTAL_IS_NOT_ENABLED!>UseExperimental<!>(Marker::class)
+@<!EXPERIMENTAL_IS_NOT_ENABLED!>OptIn<!>(Marker::class)
 fun use3() {
     f()
 }

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalIsNotEnabled.txt

@@ -3,9 +3,9 @@ package
 @Marker public fun f(): kotlin.Unit
 public fun use1(): kotlin.Unit
 @Marker public fun use2(): kotlin.Unit
-@kotlin.UseExperimental(markerClass = {Marker::class}) public fun use3(): kotlin.Unit
+@kotlin.OptIn(markerClass = {Marker::class}) public fun use3(): kotlin.Unit
 
-@kotlin.Experimental public final annotation class Marker : kotlin.Annotation {
+@kotlin.RequiresOptIn public final annotation class Marker : kotlin.Annotation {
     public constructor Marker()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnWholeModule.fir.kt

@@ -1,11 +1,11 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !EXPERIMENTAL: api.ExperimentalAPI
 // MODULE: api
 // FILE: api.kt
 
 package api
 
-@Experimental
+@RequiresOptIn
 annotation class ExperimentalAPI
 
 @ExperimentalAPI

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnWholeModule.kt

@@ -1,11 +1,11 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !EXPERIMENTAL: api.ExperimentalAPI
 // MODULE: api
 // FILE: api.kt
 
 package api
 
-@Experimental
+@RequiresOptIn
 annotation class ExperimentalAPI
 
 @ExperimentalAPI

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnWholeModule.txt

@@ -4,7 +4,7 @@ package
 package api {
     @api.ExperimentalAPI public fun function(): kotlin.String
 
-    @kotlin.Experimental public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalUnsignedLiterals.fir.kt

@@ -1,4 +1,4 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION, -UNUSED_VARIABLE, -UNUSED_PARAMETER
 
 fun test() {
@@ -18,7 +18,7 @@ fun test() {
         5u
     )
 
-    @UseExperimental(ExperimentalUnsignedTypes::class) 42u
+    @OptIn(ExperimentalUnsignedTypes::class) 42u
 }
 
 fun takeAll(

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalUnsignedLiterals.kt

@@ -1,4 +1,4 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_EXPRESSION, -UNUSED_VARIABLE, -UNUSED_PARAMETER
 
 fun test() {
@@ -18,7 +18,7 @@ fun test() {
         <!EXPERIMENTAL_UNSIGNED_LITERALS!>5u<!>
     )
 
-    @UseExperimental(ExperimentalUnsignedTypes::class) 42u
+    @OptIn(ExperimentalUnsignedTypes::class) 42u
 }
 
 fun takeAll(

compiler/testData/diagnostics/testsWithStdLib/experimental/fullFqNameUsage.fir.kt

@@ -1,11 +1,11 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 package test.abc
 
-@Experimental
+@RequiresOptIn
 annotation class E
 
-@UseExperimental(test.abc.E::class)
+@OptIn(test.abc.E::class)
 fun f() {}
 
 @test.abc.E

compiler/testData/diagnostics/testsWithStdLib/experimental/fullFqNameUsage.kt

@@ -1,11 +1,11 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 package test.abc
 
-@Experimental
+@RequiresOptIn
 annotation class E
 
-@UseExperimental(test.abc.E::class)
+@OptIn(test.abc.E::class)
 fun f() {}
 
 @test.abc.E

compiler/testData/diagnostics/testsWithStdLib/experimental/fullFqNameUsage.txt

@@ -3,10 +3,10 @@ package
 package test {
 
     package test.abc {
-        @kotlin.UseExperimental(markerClass = {test.abc.E::class}) public fun f(): kotlin.Unit
+        @kotlin.OptIn(markerClass = {test.abc.E::class}) public fun f(): kotlin.Unit
         @test.abc.E public fun g(): kotlin.Unit
 
-        @kotlin.Experimental public final annotation class E : kotlin.Annotation {
+        @kotlin.RequiresOptIn public final annotation class E : kotlin.Annotation {
             public constructor E()
             public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
             public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/importStatement.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package feature.experimental.self
 
-@Experimental
+@RequiresOptIn
 annotation class ImportedMarker
 
 @ImportedMarker

compiler/testData/diagnostics/testsWithStdLib/experimental/importStatement.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package feature.experimental.self
 
-@Experimental
+@RequiresOptIn
 annotation class ImportedMarker
 
 @ImportedMarker

compiler/testData/diagnostics/testsWithStdLib/experimental/importStatement.txt

@@ -16,7 +16,7 @@ package feature {
                 public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
             }
 
-            @kotlin.Experimental public final annotation class ImportedMarker : kotlin.Annotation {
+            @kotlin.RequiresOptIn public final annotation class ImportedMarker : kotlin.Annotation {
                 public constructor ImportedMarker()
                 public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
                 public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectTargetsForExperimentalAnnotation.fir.kt

@@ -1,25 +1,25 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
 import kotlin.annotation.AnnotationTarget.*
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(CLASS, ANNOTATION_CLASS, TYPE_PARAMETER, PROPERTY, FIELD, LOCAL_VARIABLE, VALUE_PARAMETER, CONSTRUCTOR, FUNCTION,
         PROPERTY_GETTER, PROPERTY_SETTER, TYPE, TYPEALIAS)
 annotation class E1
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(FILE)
 annotation class E2
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(EXPRESSION)
 @Retention(AnnotationRetention.SOURCE)
 annotation class E3
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(FILE, EXPRESSION)
 @Retention(AnnotationRetention.SOURCE)
 annotation class E4

compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectTargetsForExperimentalAnnotation.kt

@@ -1,25 +1,25 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
 import kotlin.annotation.AnnotationTarget.*
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 @Target(CLASS, ANNOTATION_CLASS, TYPE_PARAMETER, PROPERTY, FIELD, LOCAL_VARIABLE, VALUE_PARAMETER, CONSTRUCTOR, FUNCTION,
         PROPERTY_GETTER, PROPERTY_SETTER, TYPE, TYPEALIAS)
 annotation class E1
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 <!EXPERIMENTAL_ANNOTATION_WITH_WRONG_TARGET!>@Target(FILE)<!>
 annotation class E2
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 <!EXPERIMENTAL_ANNOTATION_WITH_WRONG_TARGET!>@Target(EXPRESSION)<!>
 @Retention(AnnotationRetention.SOURCE)
 annotation class E3
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 <!EXPERIMENTAL_ANNOTATION_WITH_WRONG_TARGET!>@Target(FILE, EXPRESSION)<!>
 @Retention(AnnotationRetention.SOURCE)
 annotation class E4

compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectTargetsForExperimentalAnnotation.txt

@@ -2,28 +2,28 @@ package
 
 package api {
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.ANNOTATION_CLASS, AnnotationTarget.TYPE_PARAMETER, AnnotationTarget.PROPERTY, AnnotationTarget.FIELD, AnnotationTarget.LOCAL_VARIABLE, AnnotationTarget.VALUE_PARAMETER, AnnotationTarget.CONSTRUCTOR, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER, AnnotationTarget.TYPE, AnnotationTarget.TYPEALIAS}) public final annotation class E1 : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.CLASS, AnnotationTarget.ANNOTATION_CLASS, AnnotationTarget.TYPE_PARAMETER, AnnotationTarget.PROPERTY, AnnotationTarget.FIELD, AnnotationTarget.LOCAL_VARIABLE, AnnotationTarget.VALUE_PARAMETER, AnnotationTarget.CONSTRUCTOR, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER, AnnotationTarget.TYPE, AnnotationTarget.TYPEALIAS}) public final annotation class E1 : kotlin.Annotation {
         public constructor E1()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.FILE}) public final annotation class E2 : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.FILE}) public final annotation class E2 : kotlin.Annotation {
         public constructor E2()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.EXPRESSION}) @kotlin.annotation.Retention(value = AnnotationRetention.SOURCE) public final annotation class E3 : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.EXPRESSION}) @kotlin.annotation.Retention(value = AnnotationRetention.SOURCE) public final annotation class E3 : kotlin.Annotation {
         public constructor E3()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.Experimental(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.FILE, AnnotationTarget.EXPRESSION}) @kotlin.annotation.Retention(value = AnnotationRetention.SOURCE) public final annotation class E4 : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Target(allowedTargets = {AnnotationTarget.FILE, AnnotationTarget.EXPRESSION}) @kotlin.annotation.Retention(value = AnnotationRetention.SOURCE) public final annotation class E4 : kotlin.Annotation {
         public constructor E4()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectUseExperimental.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 annotation class NotAMarker
 
-@UseExperimental
+@OptIn
 fun f1() {}
 
-@UseExperimental(NotAMarker::class)
+@OptIn(NotAMarker::class)
 fun f2() {}

compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectUseExperimental.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
 annotation class NotAMarker
 
-<!USE_EXPERIMENTAL_WITHOUT_ARGUMENTS!>@UseExperimental<!>
+<!USE_EXPERIMENTAL_WITHOUT_ARGUMENTS!>@OptIn<!>
 fun f1() {}
 
-<!USE_EXPERIMENTAL_ARGUMENT_IS_NOT_MARKER!>@UseExperimental(NotAMarker::class)<!>
+<!USE_EXPERIMENTAL_ARGUMENT_IS_NOT_MARKER!>@OptIn(NotAMarker::class)<!>
 fun f2() {}

compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectUseExperimental.txt

@@ -1,7 +1,7 @@
 package
 
-@kotlin.UseExperimental(markerClass = {}) public fun f1(): kotlin.Unit
+@kotlin.OptIn(markerClass = {}) public fun f1(): kotlin.Unit
-@kotlin.UseExperimental(markerClass = {NotAMarker::class}) public fun f2(): kotlin.Unit
+@kotlin.OptIn(markerClass = {NotAMarker::class}) public fun f2(): kotlin.Unit
 
 public final annotation class NotAMarker : kotlin.Annotation {
     public constructor NotAMarker()

compiler/testData/diagnostics/testsWithStdLib/experimental/override.fir.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class E
 
 open class Base {

compiler/testData/diagnostics/testsWithStdLib/experimental/override.kt

@@ -1,9 +1,9 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class E
 
 open class Base {

compiler/testData/diagnostics/testsWithStdLib/experimental/override.txt

@@ -18,7 +18,7 @@ package api {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 
-    @kotlin.Experimental(level = Level.WARNING) public final annotation class E : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) public final annotation class E : kotlin.Annotation {
         public constructor E()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/overrideDifferentExperimentalities.fir.kt

@@ -1,8 +1,8 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class E1
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class E3
 
 interface Base1 {

compiler/testData/diagnostics/testsWithStdLib/experimental/overrideDifferentExperimentalities.kt

@@ -1,8 +1,8 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class E1
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class E3
 
 interface Base1 {

compiler/testData/diagnostics/testsWithStdLib/experimental/overrideDifferentExperimentalities.txt

@@ -45,14 +45,14 @@ public final class DerivedC : Base1, Base2, Base3 {
     public open override /*3*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
-@kotlin.Experimental(level = Level.WARNING) public final annotation class E1 : kotlin.Annotation {
+@kotlin.RequiresOptIn(level = Level.WARNING) public final annotation class E1 : kotlin.Annotation {
     public constructor E1()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
-@kotlin.Experimental(level = Level.WARNING) public final annotation class E3 : kotlin.Annotation {
+@kotlin.RequiresOptIn(level = Level.WARNING) public final annotation class E3 : kotlin.Annotation {
     public constructor E3()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithStdLib/experimental/scripts.kts

@@ -1,10 +1,10 @@
-// !USE_EXPERIMENTAL: kotlin.Experimental
+// !USE_EXPERIMENTAL: kotlin.RequiresOptIn
 // !DIAGNOSTICS: -UNUSED_VARIABLE
 // FILE: api.kt
 
 package api
 
-@Experimental(Experimental.Level.WARNING)
+@RequiresOptIn(RequiresOptIn.Level.WARNING)
 annotation class ExperimentalAPI
 
 @ExperimentalAPI
@@ -24,7 +24,7 @@ fun use() {
 
 // FILE: usage-use.kts
 
-@file:UseExperimental(ExperimentalAPI::class)
+@file:OptIn(ExperimentalAPI::class)
 import api.*
 
 fun use() {

compiler/testData/diagnostics/testsWithStdLib/experimental/scripts.txt

@@ -30,7 +30,7 @@ public final class Usage_use : kotlin.script.templates.standard.ScriptTemplateWi
 package api {
     @api.ExperimentalAPI public fun function(): kotlin.String
 
-    @kotlin.Experimental(level = Level.WARNING) public final annotation class ExperimentalAPI : kotlin.Annotation {
+    @kotlin.RequiresOptIn(level = Level.WARNING) public final annotation class ExperimentalAPI : kotlin.Annotation {
         public constructor ExperimentalAPI()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int