From 3fa56e782561675b456b2bac6ea991403fb72c0b Mon Sep 17 00:00:00 2001
From: Vsevolod Tolstopyatov <qwwdfsad@gmail.com>
Date: Fri, 16 Jul 2021 17:27:27 +0300
Subject: [PATCH] Fixed a bug when onUndeliveredElement was invoked for
 normally-receive elements on JS

Fixes #2826
---
 .../channels/ChannelUndeliveredElementTest.kt     | 15 +++++++++++++++
 .../js/src/internal/LinkedList.kt                 | 15 +++++++++++++--
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/kotlinx-coroutines-core/common/test/channels/ChannelUndeliveredElementTest.kt b/kotlinx-coroutines-core/common/test/channels/ChannelUndeliveredElementTest.kt
index 9915d38fe6..f26361f2f8 100644
--- a/kotlinx-coroutines-core/common/test/channels/ChannelUndeliveredElementTest.kt
+++ b/kotlinx-coroutines-core/common/test/channels/ChannelUndeliveredElementTest.kt
@@ -123,4 +123,19 @@ class ChannelUndeliveredElementTest : TestBase() {
             check(!_cancelled.getAndSet(true)) { "Already cancelled" }
         }
     }
+
+    @Test
+    fun testHandlerIsNotInvoked() = runTest { // #2826
+        val channel = Channel<Unit> {
+            expectUnreached()
+        }
+
+        expect(1)
+        launch {
+            expect(2)
+            channel.receive()
+        }
+        channel.send(Unit)
+        finish(3)
+    }
 }
diff --git a/kotlinx-coroutines-core/js/src/internal/LinkedList.kt b/kotlinx-coroutines-core/js/src/internal/LinkedList.kt
index f2711f50af..147b31dc3e 100644
--- a/kotlinx-coroutines-core/js/src/internal/LinkedList.kt
+++ b/kotlinx-coroutines-core/js/src/internal/LinkedList.kt
@@ -32,7 +32,18 @@ public open class LinkedListNode {
         this._prev = node
     }
 
+    /*
+     * Remove that is invoked as a virtual function with a
+     * potentially augmented behaviour.
+     * I.g. `LockFreeLinkedListHead` throws, while `SendElementWithUndeliveredHandler`
+     * invokes handler on remove
+     */
     public open fun remove(): Boolean {
+        return removeImpl()
+    }
+
+    @PublishedApi
+    internal fun removeImpl(): Boolean {
         if (_removed) return false
         val prev = this._prev
         val next = this._next
@@ -76,7 +87,7 @@ public open class LinkedListNode {
     public fun removeFirstOrNull(): Node? {
         val next = _next
         if (next === this) return null
-        check(next.remove()) { "Should remove" }
+        check(next.removeImpl()) { "Should remove" }
         return next
     }
 
@@ -85,7 +96,7 @@ public open class LinkedListNode {
         if (next === this) return null
         if (next !is T) return null
         if (predicate(next)) return next
-        check(next.remove()) { "Should remove" }
+        check(next.removeImpl()) { "Should remove" }
         return next
     }
 }