Uncomment warning about -Xopt-in deprecation

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt

@@ -389,10 +389,9 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
             }
             val optInDeprecatedFqNames = optInDeprecated?.toList().orEmpty()
             if (optInDeprecatedFqNames.isNotEmpty()) {
-                // TODO: uncomment this after -opt-in bootstrapping and Gradle script fixing
-//                collector.report(
-//                    WARNING, "'-Xopt-in' is deprecated and will be removed in a future release, please use -opt-in instead"
-//                )
+                collector.report(
+                    WARNING, "'-Xopt-in' is deprecated and will be removed in a future release, please use -opt-in instead"
+                )
             }
             put(AnalysisFlags.optIn, useExperimentalFqNames + optInDeprecatedFqNames + optIn?.toList().orEmpty())
             put(AnalysisFlags.expectActualLinker, expectActualLinker)

compiler/testData/cli/jvm/experimentalDeprecatedWarning.out

@@ -1,3 +1,4 @@
 warning: '-Xuse-experimental' is deprecated and will be removed in a future release, please use -opt-in instead
+warning: '-Xopt-in' is deprecated and will be removed in a future release, please use -opt-in instead
 warning: opt-in requirement marker org.test.Warning is deprecated. Warning
 OK

compiler/testData/cli/jvm/unrestrictedBuilderInference.args

@@ -2,4 +2,4 @@ $TESTDATA_DIR$/unrestrictedBuilderInference.kt
 -d
 $TEMP_DIR$
 -Xunrestricted-builder-inference
--Xopt-in=kotlin.RequiresOptIn
+-opt-in=kotlin.RequiresOptIn

kotlin-native/backend.native/tests/build.gradle

@@ -1646,7 +1646,7 @@ linkTest("initializers_sharedVarInInitBlock") {
 
 standaloneTest("initializers_static") {
     source = "codegen/initializers/static.kt"
-    flags = ['-Xopt-in=kotlin.native.internal.InternalForKotlinNative', "-tr"]
+    flags = ['-opt-in=kotlin.native.internal.InternalForKotlinNative', "-tr"]
 }
 
 task arithmetic_basic(type: KonanLocalTest) {