Extract common parts from ExperimentalUsageChecker

core/compiler.common/src/org/jetbrains/kotlin/resolve/checkers/Experimentality.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.resolve.checkers
+
+import org.jetbrains.kotlin.name.FqName
+
+data class Experimentality(val annotationFqName: FqName, val severity: Severity, val message: String?) {
+    enum class Severity { WARNING, ERROR }
+
+    companion object {
+        val DEFAULT_SEVERITY = Severity.ERROR
+    }
+}

core/compiler.common/src/org/jetbrains/kotlin/resolve/checkers/OptInNames.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.resolve.checkers
+
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+
+object OptInNames {
+    val OLD_EXPERIMENTAL_FQ_NAME = FqName("kotlin.Experimental")
+    val OLD_USE_EXPERIMENTAL_FQ_NAME = FqName("kotlin.UseExperimental")
+    val REQUIRES_OPT_IN_FQ_NAME = FqName("kotlin.RequiresOptIn")
+    val OPT_IN_FQ_NAME = FqName("kotlin.OptIn")
+
+    val WAS_EXPERIMENTAL_FQ_NAME = FqName("kotlin.WasExperimental")
+    val USE_EXPERIMENTAL_ANNOTATION_CLASS = Name.identifier("markerClass")
+    val WAS_EXPERIMENTAL_ANNOTATION_CLASS = Name.identifier("markerClass")
+
+    val EXPERIMENTAL_FQ_NAMES = setOf(OLD_EXPERIMENTAL_FQ_NAME, REQUIRES_OPT_IN_FQ_NAME)
+    val USE_EXPERIMENTAL_FQ_NAMES = setOf(OLD_USE_EXPERIMENTAL_FQ_NAME, OPT_IN_FQ_NAME)
+}