JVM IR: output stable ABI binaries by default

#KT-43592 Fixed

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -103,8 +103,10 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
     @Argument(
         value = "-Xabi-stability",
         valueDescription = "{stable|unstable}",
-        description = "When using unstable compiler features such as FIR or JVM IR, use 'stable' to mark generated class files as stable\n" +
-                "to prevent diagnostics from stable compilers at the call site.\n"
+        description = "When using unstable compiler features such as FIR, use 'stable' to mark generated class files as stable\n" +
+                "to prevent diagnostics from stable compilers at the call site.\n" +
+                "When using the JVM IR backend, conversely, use 'unstable' to mark generated class files as unstable\n" +
+                "to force diagnostics to be reported."
     )
     var abiStability: String? by FreezableVar(null)
 
@@ -446,7 +448,7 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
         result[JvmAnalysisFlags.suppressMissingBuiltinsError] = suppressMissingBuiltinsError
         result[JvmAnalysisFlags.irCheckLocalNames] = irCheckLocalNames
         result[JvmAnalysisFlags.enableJvmPreview] = enableJvmPreview
-        result[AnalysisFlags.allowUnstableDependencies] = allowUnstableDependencies || useIR || useFir
+        result[AnalysisFlags.allowUnstableDependencies] = allowUnstableDependencies || useFir
         result[JvmAnalysisFlags.disableUltraLightClasses] = disableUltraLightClasses
         return result
     }

compiler/cli/src/org/jetbrains/kotlin/cli/common/messages/AnalyzerWithCompilerReport.kt

@@ -182,10 +182,10 @@ class AnalyzerWithCompilerReport(
                 )
             }
 
-            if (diagnostics.any { it.factory == Errors.IR_COMPILED_CLASS }) {
+            if (diagnostics.any { it.factory == Errors.IR_WITH_UNSTABLE_ABI_COMPILED_CLASS }) {
                 messageCollector.report(
                     ERROR,
-                    "Classes compiled by a new Kotlin compiler backend were found in dependencies. " +
+                    "Classes compiled by an unstable version of the Kotlin compiler were found in dependencies. " +
                             "Remove them from the classpath or use '-Xallow-unstable-dependencies' to suppress errors"
                 )
             }

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/jvmArguments.kt

@@ -165,7 +165,8 @@ fun CompilerConfiguration.configureAdvancedJvmOptions(arguments: K2JVMCompilerAr
 
     put(JVMConfigurationKeys.PARAMETERS_METADATA, arguments.javaParameters)
 
-    put(JVMConfigurationKeys.IR, (arguments.useIR && !arguments.noUseIR) || arguments.useFir)
+    val useIR = (arguments.useIR && !arguments.noUseIR) || arguments.useFir
+    put(JVMConfigurationKeys.IR, useIR)
 
     val abiStability = JvmAbiStability.fromStringOrNull(arguments.abiStability)
     if (arguments.abiStability != null) {
@@ -174,6 +175,8 @@ fun CompilerConfiguration.configureAdvancedJvmOptions(arguments: K2JVMCompilerAr
                 ERROR,
                 "Unknown ABI stability mode: ${arguments.abiStability}, supported modes: ${JvmAbiStability.values().map { it.description }}"
             )
+        } else if (!useIR && abiStability == JvmAbiStability.UNSTABLE) {
+            messageCollector.report(ERROR, "-Xabi-stability=unstable is not supported in the old JVM backend")
         } else {
             put(JVMConfigurationKeys.ABI_STABILITY, abiStability)
         }