[TEST] 2/2 Allow TEST_ONLY language features during testing

KT-75113

The commit fixes a bunch of org.jetbrains.kotlin.konan.test.blackbox.FirNativeCodegenBoxTestGenerated tests,
that got broken by the previous commit. In total, 53 tests were broken
by the previous commit.

The downside of this commit is that it's no longer possible to "test"
the effect of `TEST_ONLY` in our test infra. Well, yes, it's part of the
contract of `TEST_ONLY`, I think it's fine, that's why I have to remove
`internalArgTestOnlyFeature` test

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

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.cli.common.arguments
 
+import com.intellij.openapi.application.ApplicationManager
 import org.jetbrains.kotlin.cli.common.messages.CompilerMessageSeverity
 import org.jetbrains.kotlin.config.LanguageFeature
 
@@ -74,7 +75,7 @@ class LanguageSettingsParser : AbstractInternalArgumentParser<ManualLanguageFeat
         val languageFeature = LanguageFeature.fromString(languageFeatureName)
             ?: return reportAndReturnNull("Unknown language feature '$languageFeatureName' in passed internal argument '$wholeArgument'")
 
-        if (languageFeature.kind.testOnly) {
+        if (languageFeature.kind.testOnly && !areTestOnlyLanguageFeaturesAllowed) {
             reportAndReturnNull(
                 "Language feature '$languageFeatureName' is test-only and cannot be enabled from command line",
                 severity = CompilerMessageSeverity.ERROR
@@ -85,6 +86,15 @@ class LanguageSettingsParser : AbstractInternalArgumentParser<ManualLanguageFeat
     }
 }
 
+fun allowTestsOnlyLanguageFeatures() {
+    System.setProperty("kotlinc.test.allow.testonly.language.features", "true")
+}
+
+private val areTestOnlyLanguageFeaturesAllowed: Boolean by lazy {
+    // Use system property because test infra in K/N uses an "isolated" classloader
+    System.getProperty("kotlinc.test.allow.testonly.language.features")?.toBoolean() == true
+}
+
 interface InternalArgument {
     val stringRepresentation: String
 }

native/native.tests/tests/org/jetbrains/kotlin/konan/test/blackbox/AbstractNativeBlackBoxTest.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.konan.test.blackbox
 
 import com.intellij.testFramework.TestDataFile
+import org.jetbrains.kotlin.cli.common.arguments.allowTestsOnlyLanguageFeatures
 import org.jetbrains.kotlin.konan.test.blackbox.support.NativeBlackBoxTestSupport
 import org.jetbrains.kotlin.konan.test.blackbox.support.PackageName
 import org.jetbrains.kotlin.konan.test.blackbox.support.TestCaseId
@@ -35,6 +36,7 @@ abstract class AbstractNativeBlackBoxTest {
      * This function should be called from a method annotated with [org.junit.jupiter.api.Test].
      */
     open fun runTest(@TestDataFile testDataFilePath: String) {
+        allowTestsOnlyLanguageFeatures()
         val absoluteTestFile = getAbsoluteFile(testDataFilePath)
         val testCaseId = TestCaseId.TestDataFile(absoluteTestFile)
         try {

native/native.tests/tests/org/jetbrains/kotlin/konan/test/blackbox/AbstractNativeSimpleTest.kt

@@ -5,20 +5,27 @@
 
 package org.jetbrains.kotlin.konan.test.blackbox
 
+import org.jetbrains.kotlin.cli.common.arguments.allowTestsOnlyLanguageFeatures
 import org.jetbrains.kotlin.konan.test.blackbox.support.NativeSimpleTestSupport
 import org.jetbrains.kotlin.konan.test.blackbox.support.TestCase
 import org.jetbrains.kotlin.konan.test.blackbox.support.runner.SimpleTestRunProvider
 import org.jetbrains.kotlin.konan.test.blackbox.support.runner.TestExecutable
 import org.jetbrains.kotlin.konan.test.blackbox.support.runner.TestRunners.createProperTestRunner
 import org.jetbrains.kotlin.konan.test.blackbox.support.settings.SimpleTestRunSettings
 import org.jetbrains.kotlin.test.backend.handlers.UpdateTestDataSupport
+import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.extension.ExtendWith
 
 @ExtendWith(NativeSimpleTestSupport::class, UpdateTestDataSupport::class)
 abstract class AbstractNativeSimpleTest {
     lateinit var testRunSettings: SimpleTestRunSettings
     internal lateinit var testRunProvider: SimpleTestRunProvider
 
+    @BeforeEach
+    fun setup() {
+        allowTestsOnlyLanguageFeatures()
+    }
+
     fun runExecutableAndVerify(testCase: TestCase, executable: TestExecutable) {
         val testRun = testRunProvider.getTestRun(testCase, executable)
         val testRunner = createProperTestRunner(testRun, testRunSettings)