KT-57598 Run Kapt with K1 even when the compiler is run with K2

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

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.cli.common
 import com.intellij.ide.highlighter.JavaFileType
 import org.jetbrains.kotlin.cli.common.arguments.CommonCompilerArguments
 import org.jetbrains.kotlin.cli.common.arguments.CommonToolArguments
+import org.jetbrains.kotlin.cli.common.arguments.K2JVMCompilerArguments
 import org.jetbrains.kotlin.cli.common.arguments.ManualLanguageFeatureSetting
 import org.jetbrains.kotlin.cli.common.messages.CompilerMessageSeverity
 import org.jetbrains.kotlin.cli.common.messages.MessageCollector
@@ -23,6 +24,8 @@ fun <A : CommonCompilerArguments> CompilerConfiguration.setupCommonArguments(
     arguments: A,
     createMetadataVersion: ((IntArray) -> BinaryVersion)? = null
 ) {
+    val messageCollector = getNotNull(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY)
+
     put(CommonConfigurationKeys.DISABLE_INLINE, arguments.noInline)
     put(CommonConfigurationKeys.USE_FIR_EXTENDED_CHECKERS, arguments.useFirExtendedCheckers)
     put(CommonConfigurationKeys.EXPECT_ACTUAL_LINKER, arguments.expectActualLinker)
@@ -35,7 +38,6 @@ fun <A : CommonCompilerArguments> CompilerConfiguration.setupCommonArguments(
     val metadataVersionString = arguments.metadataVersion
     if (metadataVersionString != null) {
         val versionArray = BinaryVersion.parseVersionArray(metadataVersionString)
-        val messageCollector = getNotNull(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY)
         when {
             versionArray == null -> messageCollector.report(
                 CompilerMessageSeverity.ERROR, "Invalid metadata version: $metadataVersionString", null
@@ -45,6 +47,7 @@ fun <A : CommonCompilerArguments> CompilerConfiguration.setupCommonArguments(
         }
     }
 
+    switchToFallbackModeIfNecessary(arguments, messageCollector)
     setupLanguageVersionSettings(arguments)
 
     val usesK2 = arguments.useK2 || languageVersionSettings.languageVersion.usesK2
@@ -53,6 +56,29 @@ fun <A : CommonCompilerArguments> CompilerConfiguration.setupCommonArguments(
     buildHmppModuleStructure(arguments)?.let { put(CommonConfigurationKeys.HMPP_MODULE_STRUCTURE, it) }
 }
 
+fun switchToFallbackModeIfNecessary(arguments: CommonCompilerArguments, messageCollector: MessageCollector) {
+    val isK2 = arguments.useK2 || (arguments.languageVersion?.startsWith('2') ?: (LanguageVersion.LATEST_STABLE >= LanguageVersion.KOTLIN_2_0))
+    if (isK2) {
+        val isKaptUsed = arguments.pluginOptions?.any { it.startsWith("plugin:org.jetbrains.kotlin.kapt3") } == true
+        if (isKaptUsed) {
+            if (!arguments.suppressVersionWarnings) {
+                messageCollector.report(
+                    CompilerMessageSeverity.STRONG_WARNING,
+                    "Kapt currently doesn't support language version 2.0+.\nFalling back to 1.9."
+                )
+            }
+            arguments.languageVersion = LanguageVersion.KOTLIN_1_9.versionString
+            if (arguments.apiVersion?.startsWith("2") == true) {
+                arguments.apiVersion = ApiVersion.KOTLIN_1_9.versionString
+            }
+            arguments.useK2 = false
+            arguments.skipMetadataVersionCheck = true
+            arguments.skipPrereleaseCheck = true
+            (arguments as? K2JVMCompilerArguments)?.allowUnstableDependencies = true
+        }
+    }
+}
+
 fun <A : CommonCompilerArguments> CompilerConfiguration.setupLanguageVersionSettings(arguments: A) {
     languageVersionSettings = arguments.toLanguageVersionSettings(getNotNull(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY))
 }