Mark expect/actual classifiers as experimental

^KT-61573 Fixed
Review: https://jetbrains.team/p/kt/reviews/11969/timeline

Tests:
- MultiPlatformIntegrationTestGenerated
- CliTestGenerated
- MultiPlatformIntegrationTestGenerated
- DiagnosticTestGenerated.Multiplatform
- FirLightTreeOldFrontendDiagnosticsTestGenerated

Also add -Xexpect-actual-classes flag to all necessary ./libraries/* modules
Otherwise compilation of those modules failes because of `-Werror`

compiler/testData/cli/js/jsExtraHelp.out

@@ -87,6 +87,8 @@ where advanced options include:
                              The corresponding calls' declarations may not be marked with @BuilderInference.
   -Xklib-enable-signature-clash-checks
                              Enable the checks on uniqueness of signatures
+  -Xexpect-actual-classes    The expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature.
+                             Kotlin reports a warning every time you use them. You can use this flag to mute the warning.
   -Xexpect-actual-linker     Enable experimental expect/actual linker
   -Xexplicit-api={strict|warning|disable}
                              Force compiler to report errors on all public API declarations without explicit visibility or return type.

compiler/testData/cli/jvm/extraHelp.out

@@ -178,6 +178,8 @@ where advanced options include:
                              The corresponding calls' declarations may not be marked with @BuilderInference.
   -Xklib-enable-signature-clash-checks
                              Enable the checks on uniqueness of signatures
+  -Xexpect-actual-classes    The expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature.
+                             Kotlin reports a warning every time you use them. You can use this flag to mute the warning.
   -Xexpect-actual-linker     Enable experimental expect/actual linker
   -Xexplicit-api={strict|warning|disable}
                              Force compiler to report errors on all public API declarations without explicit visibility or return type.

compiler/testData/cli/jvm/firMultiplatformCompilationWithPsiWithoutErrors.out

@@ -9,4 +9,10 @@ as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!
 
 warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+compiler/testData/cli/jvm/firMultiplatformCompilationWithoutErrors/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect interface A {
+^
+compiler/testData/cli/jvm/firMultiplatformCompilationWithoutErrors/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual interface A {
+^
 OK

compiler/testData/cli/jvm/firMultiplatformCompilationWithoutErrors.out

@@ -9,4 +9,10 @@ as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!
 
 warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+compiler/testData/cli/jvm/firMultiplatformCompilationWithoutErrors/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect interface A {
+^
+compiler/testData/cli/jvm/firMultiplatformCompilationWithoutErrors/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual interface A {
+^
 OK

compiler/testData/cli/jvm/hmpp/lowLanguageVersion.out

@@ -8,4 +8,16 @@ as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!
 
 warning: -Xfragments flag is not supported for language version < 2.0
+compiler/testData/cli/jvm/hmpp/src/a.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class A {
+^
+compiler/testData/cli/jvm/hmpp/src/a.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class B {
+^
+compiler/testData/cli/jvm/hmpp/src/b.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class A {
+^
+compiler/testData/cli/jvm/hmpp/src/c.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class B {
+^
 OK

compiler/testData/cli/jvm/hmpp/successfulCompilation.out

@@ -8,4 +8,16 @@ as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!
 
 warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+compiler/testData/cli/jvm/hmpp/src/a.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class A {
+^
+compiler/testData/cli/jvm/hmpp/src/a.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class B {
+^
+compiler/testData/cli/jvm/hmpp/src/b.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class A {
+^
+compiler/testData/cli/jvm/hmpp/src/c.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class B {
+^
 OK

compiler/testData/cli/jvm/hmpp/successfulCompilation2.out

@@ -8,4 +8,16 @@ as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!
 
 warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+compiler/testData/cli/jvm/hmpp/src/a.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class A {
+^
+compiler/testData/cli/jvm/hmpp/src/a.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class B {
+^
+compiler/testData/cli/jvm/hmpp/src/b.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class A {
+^
+compiler/testData/cli/jvm/hmpp/src/c.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class B {
+^
 OK

compiler/testData/cli/jvm/k2SimpleMultiplatformGenericClass.out

@@ -1,2 +1,8 @@
 warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features
+compiler/testData/cli/jvm/k2SimpleMultiplatformGenericClass/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class AtomicRef<T> {
+^
+compiler/testData/cli/jvm/k2SimpleMultiplatformGenericClass/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class AtomicRef<T> constructor(value: T) {
+^
 OK

compiler/testData/cli/metadata/optionalExpectationUsage.out

@@ -1 +1,4 @@
+compiler/testData/cli/metadata/optionalExpectationUsage.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class Ann()
+^
 OK

compiler/testData/diagnostics/tests/multiplatform/expectActualClassesAreExperimentalWarning.fir.kt

@@ -0,0 +1,49 @@
+// ENABLE_EXPECT_ACTUAL_CLASSES_WARNING
+// MODULE: m1-common
+// FILE: common.kt
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>expect<!> class Clazz {
+    class <!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>Nested<!>
+
+    fun memberFun()
+    val memberProp: Clazz
+}
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>expect<!> interface Interface
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>expect<!> object Object
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>expect<!> annotation class Annotation
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>expect<!> enum class Enum
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>expect<!> class ActualTypealias
+
+expect fun function()
+
+expect val property: Clazz
+
+// MODULE: m2-jvm()()(m1-common)
+// FILE: jvm.kt
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> class Clazz {
+    <!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> class Nested
+
+    actual fun memberFun() {}
+    actual val memberProp: Clazz = null!!
+}
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> interface Interface
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> object Object
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> annotation class Annotation
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> enum class Enum
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> typealias ActualTypealias = ActualTypealiasImpl
+
+class ActualTypealiasImpl
+
+actual fun function() {}
+
+actual val property: Clazz = null!!

compiler/testData/diagnostics/tests/multiplatform/expectActualClassesAreExperimentalWarning.kt

@@ -0,0 +1,49 @@
+// ENABLE_EXPECT_ACTUAL_CLASSES_WARNING
+// MODULE: m1-common
+// FILE: common.kt
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING, EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING{JVM}!>expect<!> class Clazz {
+    class <!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING, EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING{JVM}!>Nested<!>
+
+    fun memberFun()
+    val memberProp: Clazz
+}
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING, EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING{JVM}!>expect<!> interface Interface
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING, EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING{JVM}!>expect<!> object Object
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING, EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING{JVM}!>expect<!> annotation class Annotation
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING, EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING{JVM}!>expect<!> enum class Enum
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING, EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING{JVM}!>expect<!> class ActualTypealias
+
+expect fun function()
+
+expect val property: Clazz
+
+// MODULE: m2-jvm()()(m1-common)
+// FILE: jvm.kt
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> class Clazz {
+    <!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> class Nested
+
+    actual fun memberFun() {}
+    actual val memberProp: Clazz = null!!
+}
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> interface Interface
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> object Object
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> annotation class Annotation
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> enum class Enum
+
+<!EXPECT_ACTUAL_CLASSIFIERS_ARE_EXPERIMENTAL_WARNING!>actual<!> typealias ActualTypealias = ActualTypealiasImpl
+
+class ActualTypealiasImpl
+
+actual fun function() {}
+
+actual val property: Clazz = null!!

compiler/testData/multiplatform/classScopes/constructorIncorrectSignature/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/constructorIncorrectSignature/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/classScopes/enumsWithDifferentEntries/output.txt

@@ -1,6 +1,24 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/enumsWithDifferentEntries/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect enum class AB { A, B }
+^
+compiler/testData/multiplatform/classScopes/enumsWithDifferentEntries/common.kt:1:24: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect enum class AB { A, B }
+                       ^
+compiler/testData/multiplatform/classScopes/enumsWithDifferentEntries/common.kt:1:27: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect enum class AB { A, B }
+                          ^
+compiler/testData/multiplatform/classScopes/enumsWithDifferentEntries/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect enum class CD { C, D }
+^
+compiler/testData/multiplatform/classScopes/enumsWithDifferentEntries/common.kt:3:24: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect enum class CD { C, D }
+                       ^
+compiler/testData/multiplatform/classScopes/enumsWithDifferentEntries/common.kt:3:27: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect enum class CD { C, D }
+                          ^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/classScopes/fakeOverrides/output.txt

@@ -1,7 +1,25 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/fakeOverrides/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect open class Base {
+^
+compiler/testData/multiplatform/classScopes/fakeOverrides/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Derived : Base {
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/fakeOverrides/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect open class Base {
+^
+compiler/testData/multiplatform/classScopes/fakeOverrides/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Derived : Base {
+^
+compiler/testData/multiplatform/classScopes/fakeOverrides/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual open class Base {
+^
+compiler/testData/multiplatform/classScopes/fakeOverrides/jvm.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class Derived : Base() {
+^

compiler/testData/multiplatform/classScopes/functionAndPropertyWithSameName/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/functionAndPropertyWithSameName/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/classScopes/functionIncorrectSignature/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/functionIncorrectSignature/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/classScopes/functionIncorrectSignatureFromSuperclass/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/functionIncorrectSignatureFromSuperclass/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/classScopes/missingConstructor/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/missingConstructor/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/classScopes/missingFunction/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/missingFunction/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/classScopes/simple/output.txt

@@ -1,8 +1,16 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/classScopes/simple/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo(param: String) {
+^
 
 -- JVM --
 Exit code: OK
 Output:
-
+compiler/testData/multiplatform/classScopes/simple/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo(param: String) {
+^
+compiler/testData/multiplatform/classScopes/simple/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class Foo actual constructor(param: String) {
+^

compiler/testData/multiplatform/createImplClassInPlatformModule/output.txt

@@ -1,7 +1,16 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/createImplClassInPlatformModule/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/createImplClassInPlatformModule/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo
+^
+compiler/testData/multiplatform/createImplClassInPlatformModule/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class Foo(x: Int) {
+^

compiler/testData/multiplatform/defaultArguments/methodDefaultArgsViaTypealias/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/defaultArguments/methodDefaultArgsViaTypealias/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class A(p: String = "constructor") {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR
@@ -11,4 +14,4 @@ compiler/testData/multiplatform/defaultArguments/methodDefaultArgsViaTypealias/j
     public final expect fun foo(p: String = ...): Unit
 
 actual typealias A = AImpl
-^
+^

compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/output.txt

@@ -1,10 +1,37 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C(x: Int, y: String = "OK")
+^
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/common.kt:7:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class Anno1(val x: Int, val y: String = "OK")
+^
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/common.kt:9:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class Anno2(val x: Int, val y: String = "OK")
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C(x: Int, y: String = "OK")
+^
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/common.kt:7:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class Anno1(val x: Int, val y: String = "OK")
+^
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/common.kt:9:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class Anno2(val x: Int, val y: String = "OK")
+^
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/jvm.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class C actual constructor(x: Int, y: String) {}
+^
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/jvm.kt:7:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual annotation class Anno1(actual val x: Int, actual val y: String = "OK")
+^
+compiler/testData/multiplatform/defaultArguments/useDefaultArgumentsInDependency/jvm.kt:9:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual annotation class Anno2(actual val x: Int, actual val y: String)
+^
 
 -- JVM (2) --
 Exit code: OK

compiler/testData/multiplatform/explicitActualOnOverrideOfAbstractMethod/output.txt

@@ -1,7 +1,25 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/explicitActualOnOverrideOfAbstractMethod/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect abstract class Base {
+^
+compiler/testData/multiplatform/explicitActualOnOverrideOfAbstractMethod/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class DerivedImplicit : Base {
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/explicitActualOnOverrideOfAbstractMethod/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect abstract class Base {
+^
+compiler/testData/multiplatform/explicitActualOnOverrideOfAbstractMethod/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class DerivedImplicit : Base {
+^
+compiler/testData/multiplatform/explicitActualOnOverrideOfAbstractMethod/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual abstract class Base {
+^
+compiler/testData/multiplatform/explicitActualOnOverrideOfAbstractMethod/jvm.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class DerivedImplicit : Base() {
+^

compiler/testData/multiplatform/genericDeclarations/output.txt

@@ -1,6 +1,18 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/genericDeclarations/common.kt:9:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C1<A>
+^
+compiler/testData/multiplatform/genericDeclarations/common.kt:10:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C2<B : C2<B>>
+^
+compiler/testData/multiplatform/genericDeclarations/common.kt:11:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C3<D, E : MutableList<in D>>
+^
+compiler/testData/multiplatform/genericDeclarations/common.kt:13:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect abstract class AbstractList<F> : MutableList<F>
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/implTypeAlias/actualTypealiasToNothing/output.txt

@@ -1,6 +1,12 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/actualTypealiasToNothing/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class E01
+^
+compiler/testData/multiplatform/implTypeAlias/actualTypealiasToNothing/common.kt:2:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class E02
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/implTypeAlias/actualTypealiasToNullableType/output.txt

@@ -1,6 +1,12 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/actualTypealiasToNullableType/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class E01
+^
+compiler/testData/multiplatform/implTypeAlias/actualTypealiasToNullableType/common.kt:2:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class E02
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/output.txt

@@ -1,10 +1,19 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class A
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class A
+^
+compiler/testData/multiplatform/implTypeAlias/discriminateHeaderClassInFavorOfTypeAlias/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual typealias A = AImpl
+^
 
 -- JVM (2) --
 Exit code: OK

compiler/testData/multiplatform/implTypeAlias/generic/output.txt

@@ -1,11 +1,19 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/generic/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C1<A> {
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/generic/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C1<A> {
+^
+compiler/testData/multiplatform/implTypeAlias/generic/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual typealias C1<A> = C1Impl<A>
+^
 compiler/testData/multiplatform/implTypeAlias/generic/jvm.kt:3:13: warning: parameter 'a' is never used
     fun foo(a: A): List<A>? = null
             ^
-

compiler/testData/multiplatform/implTypeAlias/nestedClassesViaTypeAlias/output.txt

@@ -1,7 +1,22 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/nestedClassesViaTypeAlias/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class ByTypeAlias {
+^
+compiler/testData/multiplatform/implTypeAlias/nestedClassesViaTypeAlias/common.kt:2:15: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    interface Nested
+              ^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/implTypeAlias/nestedClassesViaTypeAlias/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class ByTypeAlias {
+^
+compiler/testData/multiplatform/implTypeAlias/nestedClassesViaTypeAlias/common.kt:2:15: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    interface Nested
+              ^
+compiler/testData/multiplatform/implTypeAlias/nestedClassesViaTypeAlias/jvm.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual typealias ByTypeAlias = ByTypeAliasImpl
+^

compiler/testData/multiplatform/incompatibleClasses/output.txt

@@ -1,6 +1,57 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/incompatibleClasses/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class PClass
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:2:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect interface PInterface
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect object PObject
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:4:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect enum class PEnumClass
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class PAnnotationClass
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:7:10: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+internal expect object InternalObject
+         ^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:8:8: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+public expect object PublicObject
+       ^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:10:6: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+open expect class OpenClass
+     ^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:11:10: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+abstract expect class AbstractClass
+         ^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:12:7: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+final expect class FinalClass
+      ^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:14:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C1<A>
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:15:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C2<B>
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:16:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C3<D, E : D>
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:18:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class C4<F>
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:21:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect abstract class ExtendsNumber : Number
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:23:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect fun interface FunInterface {
+^
+compiler/testData/multiplatform/incompatibleClasses/common.kt:27:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect fun interface FunInterface2 {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/incompatibleNestedClasses/output.txt

@@ -1,6 +1,42 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class O1 {
+^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:2:11: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    class N1
+          ^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:3:15: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    interface N2
+              ^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:4:12: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    object N3
+           ^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:7:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class O2 {
+^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:8:11: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    class N2
+          ^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:9:17: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    inner class I2
+                ^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:12:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class O3 {
+^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:13:12: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    object Companion
+           ^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:14:22: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    companion object Factory
+                     ^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:17:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class O4 {
+^
+compiler/testData/multiplatform/incompatibleNestedClasses/common.kt:18:15: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+    companion object
+              ^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/incorrectImplInClass/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/incorrectImplInClass/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/inlineClasses/output.txt

@@ -1,9 +1,15 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/inlineClasses/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect inline class Foo1(val x: Int)
+^
 compiler/testData/multiplatform/inlineClasses/common.kt:3:8: warning: 'inline' modifier is deprecated. Use 'value' instead
 expect inline class Foo1(val x: Int)
        ^
+compiler/testData/multiplatform/inlineClasses/common.kt:4:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect inline class Foo2(val y: String)
+^
 compiler/testData/multiplatform/inlineClasses/common.kt:4:8: warning: 'inline' modifier is deprecated. Use 'value' instead
 expect inline class Foo2(val y: String)
        ^

compiler/testData/multiplatform/jsNameClash/output.txt

@@ -1,7 +1,16 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/jsNameClash/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class ClassWithImplByExtension
+^
 
 -- JS --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/jsNameClash/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class ClassWithImplByExtension
+^
+compiler/testData/multiplatform/jsNameClash/js.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class ClassWithImplByExtension
+^

compiler/testData/multiplatform/missingOverload/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/missingOverload/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo {
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/optionalExpectation/output.txt

@@ -1,11 +1,23 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/optionalExpectation/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class A()
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/optionalExpectation/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class A()
+^
+compiler/testData/multiplatform/optionalExpectation/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual annotation class A
+^
 
 -- JS --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/optionalExpectation/common.kt:5:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect annotation class A()
+^

compiler/testData/multiplatform/regressions/incompatibleClassScopesWithImplTypeAlias/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/regressions/incompatibleClassScopesWithImplTypeAlias/common.kt:3:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect abstract class Writer protected constructor()
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR

compiler/testData/multiplatform/simple/output.txt

@@ -1,11 +1,26 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/simple/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Printer() {
+^
 
 -- JVM --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/simple/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Printer() {
+^
+compiler/testData/multiplatform/simple/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class Printer {
+^
 
 -- JS --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/simple/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Printer() {
+^
+compiler/testData/multiplatform/simple/js.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+actual class Printer {
+^

compiler/testData/multiplatform/weakIncompatibilityWithoutActualModifier/output.txt

@@ -1,6 +1,9 @@
 -- Common --
 Exit code: OK
 Output:
+compiler/testData/multiplatform/weakIncompatibilityWithoutActualModifier/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning.
+expect class Foo
+^
 
 -- JVM --
 Exit code: COMPILATION_ERROR