[cinterop] A bit more robust logic of mode selection

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/jvm/main.kt

@@ -211,8 +211,17 @@ private fun processCLib(args: Array<String>, additionalArgs: Map<String, Any> =
 
     val outKtPkg = fqParts.joinToString(".")
 
-    val mode = parseGenerationMode(cinteropArguments.mode)
+    val mode = run {
-            ?: error ("Unexpected interop generation mode: ${cinteropArguments.mode}")
+        val providedMode = parseGenerationMode(cinteropArguments.mode)
+                ?: error ("Unexpected interop generation mode: ${cinteropArguments.mode}")
+
+        if (providedMode == GenerationMode.METADATA && flavor == KotlinPlatform.JVM) {
+            warn("Metadata mode isn't supported for Kotlin/JVM! Falling back to sourcecode.")
+            GenerationMode.SOURCE_CODE
+        } else {
+            providedMode
+        }
+    }
 
     val allLibraryDependencies = when (flavor) {
         KotlinPlatform.NATIVE -> resolveDependencies(cinteropArguments, tool.target)

build-tools/src/main/groovy/org/jetbrains/kotlin/NativeInteropPlugin.groovy

@@ -225,6 +225,9 @@ class NamedNativeInteropConfig implements Named {
                 args '-natives', nativeLibsDir
                 args '-Xtemporary-files-dir', temporaryFilesDir
                 args '-flavor', this.flavor
+                if (flavor == "jvm") {
+                    args '-mode', 'sourcecode'
+                }
                 // Uncomment to debug.
                 // args '-verbose', 'true'