module: fix cyclical dynamic import

bmeck · MylesBorins · commit 95f6467ffdbc · 2018-03-07T09:29:50.000-08:00
ensures that instantiation result is only used during initial loading PR-URL: #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>
diff --git 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
@@ -0,0 +1,3 @@
+// Flags: --experimental-modules
+import '../common';
+import('./test-esm-cyclic-dynamic-import');

Original file line number	Diff line number	Diff line change
`@@ -50,10 +50,11 @@ class ModuleJob {`
`50`	`50`	`}`
`51`	`51`
`52`	`52`	`async instantiate() {`
`53`		`- if (this.instantiated) {`
`54`		`- return this.instantiated;`
	`53`	`+ if (!this.instantiated) {`
	`54`	`+ return this.instantiated = this._instantiate();`
`55`	`55`	`}`
`56`		`- return this.instantiated = this._instantiate();`
	`56`	`+ await this.instantiated;`
	`57`	`+ return this.module;`
`57`	`58`	`}`
`58`	`59`
`59`	`60`	`// This method instantiates the module associated with this job and its`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+// Flags: --experimental-modules`
	`2`	`+import '../common';`
	`3`	`+import('./test-esm-cyclic-dynamic-import');`