From 9b47a321d5650ec3215ee907418deac16896ed09 Mon Sep 17 00:00:00 2001
From: Anton Bannykh <anton.bannykh@jetbrains.com>
Date: Mon, 6 Dec 2021 11:13:27 +0300
Subject: [PATCH] [JS IR] assert there are no clashing declarations

---
 .../ir/backend/js/transformers/irToJs/Merger.kt     | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/Merger.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/Merger.kt
index 56f2ff53e69..e805660c6bd 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/Merger.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/Merger.kt
@@ -115,7 +115,20 @@ class Merger(
         return rootNode
     }
 
+    private fun assertSingleDefinition() {
+        val definitions = mutableSetOf<String>()
+        fragments.forEach {
+            it.definitions.forEach {
+                if (!definitions.add(it)) {
+                    error("Clashing definitions with tag '$it'")
+                }
+            }
+        }
+    }
+
     fun merge(): JsProgram {
+        assertSingleDefinition()
+
         linkJsNames()
 
         val moduleBody = mutableListOf<JsStatement>().also {