JVM_IR: fix source file name for mutlifile class facades

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ClassCodegen.kt

@@ -153,7 +153,9 @@ abstract class ClassCodegen protected constructor(
         if (withinInline || !smap.isTrivial) {
             visitor.visitSMAP(smap, !context.state.languageVersionSettings.supportsFeature(LanguageFeature.CorrectSourceMappingSyntax))
         } else {
-            visitor.visitSource(smap.sourceInfo!!.source, null)
+            smap.sourceInfo!!.sourceFileName?.let {
+                visitor.visitSource(it, null)
+            }
         }
 
         visitor.done()

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/irCodegenUtils.kt

@@ -87,15 +87,19 @@ fun JvmBackendContext.getSourceMapper(declaration: IrClass): SourceMapper {
     // NOTE: apparently inliner requires the source range to cover the
     //       whole file the class is declared in rather than the class only.
     // TODO: revise
-    val endLineNumber = when {
-        fileEntry is MultifileFacadeFileEntry -> 0
+    val endLineNumber = when (fileEntry) {
+        is MultifileFacadeFileEntry -> 0
         else -> fileEntry?.getSourceRangeInfo(0, fileEntry.maxOffset)?.endLineNumber ?: 0
     }
+    val sourceFileName = when (fileEntry) {
+        is MultifileFacadeFileEntry -> fileEntry.partFiles.singleOrNull()?.name
+        else -> declaration.fileParent.name
+    }
     return SourceMapper(
-        SourceInfo.createInfoForIr(
-            endLineNumber + 1,
+        SourceInfo(
+            sourceFileName,
             typeMapper.mapClass(declaration).internalName,
-            declaration.fileParent.name
+            endLineNumber + 1
         )
     )
 }