From bc1038ab5b9318a6999ed4453414b380f45d6714 Mon Sep 17 00:00:00 2001
From: Bradley Farias <bradley.meck@gmail.com>
Date: Fri, 23 Feb 2018 14:21:49 -0600
Subject: [PATCH] module: fix cyclical dynamic import

ensures that instantiation result is only used during initial loading

PR-URL: https://github.com/nodejs/node/pull/18965
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
---
 lib/internal/loader/ModuleJob.js                  | 7 ++++---
 test/es-module/test-esm-cyclic-dynamic-import.mjs | 3 +++
 2 files changed, 7 insertions(+), 3 deletions(-)
 create mode 100644 test/es-module/test-esm-cyclic-dynamic-import.mjs

diff --git a/lib/internal/loader/ModuleJob.js b/lib/internal/loader/ModuleJob.js
index f79cc6cfe1d94a..b3553fc7235d95 100644
--- a/lib/internal/loader/ModuleJob.js
+++ b/lib/internal/loader/ModuleJob.js
@@ -50,10 +50,11 @@ class ModuleJob {
   }
 
   async instantiate() {
-    if (this.instantiated) {
-      return this.instantiated;
+    if (!this.instantiated) {
+      return this.instantiated = this._instantiate();
     }
-    return this.instantiated = this._instantiate();
+    await this.instantiated;
+    return this.module;
   }
 
   // This method instantiates the module associated with this job and its
diff --git a/test/es-module/test-esm-cyclic-dynamic-import.mjs b/test/es-module/test-esm-cyclic-dynamic-import.mjs
new file mode 100644
index 00000000000000..c8dfff919c2f7e
--- /dev/null
+++ b/test/es-module/test-esm-cyclic-dynamic-import.mjs
@@ -0,0 +1,3 @@
+// Flags: --experimental-modules
+import '../common';
+import('./test-esm-cyclic-dynamic-import');