From 4a00d1f978262dec94b26ea84c79dd986d38a36a Mon Sep 17 00:00:00 2001
From: Alexander Udalov <alexander.udalov@jetbrains.com>
Date: Fri, 23 Sep 2022 20:36:37 +0200
Subject: [PATCH] Add internal way to enable old backend

Needed for tests on debugger in Kotlin IDE plugin.
---
 .../cli/src/org/jetbrains/kotlin/cli/jvm/K2JVMCompiler.kt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/K2JVMCompiler.kt b/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/K2JVMCompiler.kt
index 764b687fdcc..3a217ac65f0 100644
--- a/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/K2JVMCompiler.kt
+++ b/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/K2JVMCompiler.kt
@@ -123,8 +123,9 @@ class K2JVMCompiler : CLICompiler<K2JVMCompilerArguments>() {
         }
 
         if (arguments.useOldBackend) {
-            messageCollector.report(ERROR, "-Xuse-old-backend is no longer supported. Please migrate to the new JVM IR backend")
-            return COMPILATION_ERROR
+            val severity = if (isUseOldBackendAllowed()) WARNING else ERROR
+            messageCollector.report(severity, "-Xuse-old-backend is no longer supported. Please migrate to the new JVM IR backend")
+            if (severity == ERROR) return COMPILATION_ERROR
         }
 
         messageCollector.report(LOGGING, "Configuring the compilation environment")
@@ -260,6 +261,9 @@ class K2JVMCompiler : CLICompiler<K2JVMCompilerArguments>() {
         val argument = arguments.profileCompilerCommand ?: return defaultPerformanceManager
         return ProfilingCompilerPerformanceManager.create(argument)
     }
+
+    private fun isUseOldBackendAllowed(): Boolean =
+        K2JVMCompiler::class.java.classLoader.getResource("META-INF/unsafe-allow-use-old-backend") != null
 }
 
 fun CompilerConfiguration.configureModuleChunk(