K2: introduce OptIn language version checker

#KT-60598 Fixed

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/config/FirOptInLanguageVersionSettingsChecker.kt

@@ -5,9 +5,45 @@
 
 package org.jetbrains.kotlin.fir.analysis.checkers.config
 
+import org.jetbrains.kotlin.config.AnalysisFlags
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.declarations.getAnnotationByClassId
+import org.jetbrains.kotlin.fir.resolve.providers.symbolProvider
+import org.jetbrains.kotlin.fir.resolve.transformers.PackageResolutionResult
+import org.jetbrains.kotlin.fir.resolve.transformers.resolveToPackageOrClass
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.resolve.checkers.OptInNames
+import org.jetbrains.kotlin.resolve.deprecation.DeprecationLevelValue
 
 object FirOptInLanguageVersionSettingsChecker : FirLanguageVersionSettingsChecker() {
     override fun check(context: CheckerContext, rawReport: (Boolean, String) -> Unit) {
+        context.languageVersionSettings.getFlag(AnalysisFlags.optIn).forEach { fqNameAsString ->
+            if (fqNameAsString != OptInNames.REQUIRES_OPT_IN_FQ_NAME.asString()) {
+                checkOptInMarkerArgument(context, fqNameAsString, rawReport)
+            }
+        }
     }
-}
+
+    private fun checkOptInMarkerArgument(context: CheckerContext, fqNameAsString: String, rawReport: (Boolean, String) -> Unit) {
+        val packageOrClass = resolveToPackageOrClass(context.session.symbolProvider, FqName(fqNameAsString))
+        val symbol = (packageOrClass as? PackageResolutionResult.PackageOrClass)?.classSymbol
+
+        if (symbol == null) {
+            rawReport(
+                false,
+                "Opt-in requirement marker $fqNameAsString is unresolved. Please make sure it's present in the module dependencies"
+            )
+            return
+        }
+
+        if (symbol.getAnnotationByClassId(OptInNames.REQUIRES_OPT_IN_CLASS_ID, context.session) == null) {
+            rawReport(false, "Class $fqNameAsString is not an opt-in requirement marker")
+            return
+        }
+        val deprecationInfo = symbol.getDeprecation(context.languageVersionSettings.apiVersion)?.all ?: return
+        rawReport(
+            deprecationInfo.deprecationLevel != DeprecationLevelValue.WARNING,
+            "Opt-in requirement marker $fqNameAsString is deprecated" + deprecationInfo.message?.let { ". $it" }.orEmpty()
+        )
+    }
+}

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/components/LanguageVersionSettingsDiagnosticComponent.kt

@@ -10,7 +10,6 @@ import org.jetbrains.kotlin.diagnostics.impl.BaseDiagnosticsCollector
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.analysis.CheckersComponentInternal
 import org.jetbrains.kotlin.fir.analysis.checkers.LanguageVersionSettingsCheckers
-import org.jetbrains.kotlin.fir.analysis.checkers.config.FirLanguageVersionSettingsChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.fir.analysis.checkersComponent
 
@@ -21,13 +20,9 @@ class LanguageVersionSettingsDiagnosticComponent(
     private val checkers: LanguageVersionSettingsCheckers = session.checkersComponent.languageVersionSettingsCheckers,
 ) : AbstractDiagnosticCollectorComponent(session, reporter) {
     override fun checkSettings(data: CheckerContext) {
-        checkers.languageVersionSettingsCheckers.check(data)
-    }
-
-    private fun Collection<FirLanguageVersionSettingsChecker>.check(context: CheckerContext) {
         val rawReport = (reporter as? BaseDiagnosticsCollector)?.rawReport ?: return
-        for (checker in this) {
-            checker.check(context, rawReport)
+        for (checker in checkers.languageVersionSettingsCheckers) {
+            checker.check(data, rawReport)
         }
     }
 }