From df3b47f3d044aea3a58e368b3dca9624c5d49c1c Mon Sep 17 00:00:00 2001
From: Antoine du HAMEL <duhamelantoine1995@gmail.com>
Date: Sun, 24 May 2020 12:15:37 +0200
Subject: [PATCH 1/2] modules: runtime deprecate module.parent

---
 doc/api/deprecations.md                       |  8 ++++-
 doc/api/modules.md                            |  4 +--
 lib/internal/modules/cjs/loader.js            | 29 +++++++++++++------
 test/fixtures/cjs-module-parent.js            |  5 ++++
 ...nt-deprecation-no-warning-for-cjs-users.js |  7 +++++
 ...rent-deprecation-warning-for-esm-users.mjs |  7 +++++
 .../test-module-parent-deprecation.js         |  3 +-
 .../test-module-parent-pending-deprecation.js | 15 ++++++++++
 8 files changed, 64 insertions(+), 14 deletions(-)
 create mode 100644 test/fixtures/cjs-module-parent.js
 create mode 100644 test/parallel/test-module-parent-deprecation-no-warning-for-cjs-users.js
 create mode 100644 test/parallel/test-module-parent-deprecation-warning-for-esm-users.mjs
 create mode 100644 test/parallel/test-module-parent-pending-deprecation.js

diff --git a/doc/api/deprecations.md b/doc/api/deprecations.md
index fa2f52c8265c2f..f3f1f718c47132 100644
--- a/doc/api/deprecations.md
+++ b/doc/api/deprecations.md
@@ -2612,6 +2612,9 @@ no longer required due to simplification of the implementation.
 ### DEP0144: `module.parent`
 <!-- YAML
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/33534
+    description: Runtime deprecation.
   - version:
     - v14.6.0
     - v12.19.0
@@ -2619,7 +2622,7 @@ changes:
     description: Documentation-only deprecation.
 -->
 
-Type: Documentation-only (supports [`--pending-deprecation`][])
+Type: Runtime (supports [`--pending-deprecation`][])
 
 A CommonJS module can access the first module that required it using
 `module.parent`. This feature is deprecated because it does not work
@@ -2643,6 +2646,9 @@ const moduleParents = Object.values(require.cache)
   .filter((m) => m.children.includes(module));
 ```
 
+Without `--pending-deprecation`, runtime warnings occur only when this property
+is accessed from a module that have a nullish value for their `module.parent`.
+
 ### DEP0145: `socket.bufferSize`
 <!-- YAML
 changes:
diff --git a/doc/api/modules.md b/doc/api/modules.md
index 48eb28fd59b96c..160be3ad22dc96 100644
--- a/doc/api/modules.md
+++ b/doc/api/modules.md
@@ -917,10 +917,10 @@ deprecated:
 > Stability: 0 - Deprecated: Please use [`require.main`][] and
 > [`module.children`][] instead.
 
-* {module | null | undefined}
+* {module | null | UnknownModule}
 
 The module that first required this one, or `null` if the current module is the
-entry point of the current process, or `undefined` if the module was loaded by
+entry point of the current process, or `UnknownModule` if the module was loaded by
 something that is not a CommonJS module (E.G.: REPL or `import`).
 
 ### `module.path`
diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 837250198b7e63..03d17fe4c5d0e7 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -241,7 +241,23 @@ ObjectDefineProperty(Module.prototype, 'isPreloading', isPreloadingDesc);
 ObjectDefineProperty(NativeModule.prototype, 'isPreloading', isPreloadingDesc);
 
 function getModuleParent() {
-  return moduleParentCache.get(this);
+  const parent = moduleParentCache.get(this);
+  if (!process.noDeprecation && !getModuleParent.warned &&
+      (parent == null || pendingDeprecation)) {
+    process.emitWarning(
+      'module.parent is deprecated due to accuracy issues. Please use ' +
+        'require.main to find program entry point instead.',
+      'DeprecationWarning',
+      'DEP0144'
+    );
+    getModuleParent.warned = true;
+  }
+  if (parent === undefined) {
+    const parent = new (class UnknownModule {})();
+    moduleParentCache.set(this, parent);
+    return parent;
+  }
+  return parent;
 }
 
 function setModuleParent(value) {
@@ -249,18 +265,13 @@ function setModuleParent(value) {
 }
 
 ObjectDefineProperty(Module.prototype, 'parent', {
-  get: pendingDeprecation ? deprecate(
-    getModuleParent,
-    'module.parent is deprecated due to accuracy issues. Please use ' +
-      'require.main to find program entry point instead.',
-    'DEP0144'
-  ) : getModuleParent,
-  set: pendingDeprecation ? deprecate(
+  get: getModuleParent,
+  set: deprecate(
     setModuleParent,
     'module.parent is deprecated due to accuracy issues. Please use ' +
       'require.main to find program entry point instead.',
     'DEP0144'
-  ) : setModuleParent,
+  ),
 });
 
 let debug = require('internal/util/debuglog').debuglog('module', (fn) => {
diff --git a/test/fixtures/cjs-module-parent.js b/test/fixtures/cjs-module-parent.js
new file mode 100644
index 00000000000000..8cb8545f230f9d
--- /dev/null
+++ b/test/fixtures/cjs-module-parent.js
@@ -0,0 +1,5 @@
+'use strict';
+const assert = require('assert');
+
+// Accessing module.parent should not be falsy.
+assert.ok(module.parent)
diff --git a/test/parallel/test-module-parent-deprecation-no-warning-for-cjs-users.js b/test/parallel/test-module-parent-deprecation-no-warning-for-cjs-users.js
new file mode 100644
index 00000000000000..ce3b0a87cc0edb
--- /dev/null
+++ b/test/parallel/test-module-parent-deprecation-no-warning-for-cjs-users.js
@@ -0,0 +1,7 @@
+'use strict';
+
+require('../common');
+const fixtures = require('../common/fixtures');
+
+// Accessing module.parent from a child module should not raise a warning.
+require(fixtures.path('cjs-module-parent.js'));
diff --git a/test/parallel/test-module-parent-deprecation-warning-for-esm-users.mjs b/test/parallel/test-module-parent-deprecation-warning-for-esm-users.mjs
new file mode 100644
index 00000000000000..3f21e6cb05439a
--- /dev/null
+++ b/test/parallel/test-module-parent-deprecation-warning-for-esm-users.mjs
@@ -0,0 +1,7 @@
+import { mustCall } from '../common/index.mjs';
+import fixtures from '../common/fixtures.js';
+
+// Accessing module.parent from a child module should raise a deprecation
+// warning when imported from ESM.
+import(fixtures.path('cjs-module-parent.js'))
+    .then(mustCall());
diff --git a/test/parallel/test-module-parent-deprecation.js b/test/parallel/test-module-parent-deprecation.js
index e2533f87d417d0..0bedca9a569a8a 100644
--- a/test/parallel/test-module-parent-deprecation.js
+++ b/test/parallel/test-module-parent-deprecation.js
@@ -1,6 +1,5 @@
-// Flags: --pending-deprecation
-
 'use strict';
+
 const common = require('../common');
 const assert = require('assert');
 
diff --git a/test/parallel/test-module-parent-pending-deprecation.js b/test/parallel/test-module-parent-pending-deprecation.js
new file mode 100644
index 00000000000000..7e4518a6aefad5
--- /dev/null
+++ b/test/parallel/test-module-parent-pending-deprecation.js
@@ -0,0 +1,15 @@
+// Flags: --pending-deprecation
+
+'use strict';
+
+const common = require('../common');
+const fixtures = require('../common/fixtures');
+
+common.expectWarning(
+  'DeprecationWarning',
+  'module.parent is deprecated due to accuracy issues. Please use ' +
+      'require.main to find program entry point instead.',
+  'DEP0144'
+);
+
+require(fixtures.path('cjs-module-parent.js'));

From 557e41a8bdcf1da7fa033ada7f62a82bab260e5a Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Wed, 10 Mar 2021 23:40:20 +0100
Subject: [PATCH 2/2] fixup! modules: runtime deprecate module.parent

---
 doc/api/modules.md                                     | 4 ++--
 lib/internal/modules/cjs/loader.js                     | 5 -----
 test/fixtures/cjs-module-parent.js                     | 6 +++---
 test/parallel/test-module-parent-setter-deprecation.js | 2 --
 4 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/doc/api/modules.md b/doc/api/modules.md
index 160be3ad22dc96..48eb28fd59b96c 100644
--- a/doc/api/modules.md
+++ b/doc/api/modules.md
@@ -917,10 +917,10 @@ deprecated:
 > Stability: 0 - Deprecated: Please use [`require.main`][] and
 > [`module.children`][] instead.
 
-* {module | null | UnknownModule}
+* {module | null | undefined}
 
 The module that first required this one, or `null` if the current module is the
-entry point of the current process, or `UnknownModule` if the module was loaded by
+entry point of the current process, or `undefined` if the module was loaded by
 something that is not a CommonJS module (E.G.: REPL or `import`).
 
 ### `module.path`
diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 03d17fe4c5d0e7..cb8bcfe82784a3 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -252,11 +252,6 @@ function getModuleParent() {
     );
     getModuleParent.warned = true;
   }
-  if (parent === undefined) {
-    const parent = new (class UnknownModule {})();
-    moduleParentCache.set(this, parent);
-    return parent;
-  }
   return parent;
 }
 
diff --git a/test/fixtures/cjs-module-parent.js b/test/fixtures/cjs-module-parent.js
index 8cb8545f230f9d..4faf35833ae788 100644
--- a/test/fixtures/cjs-module-parent.js
+++ b/test/fixtures/cjs-module-parent.js
@@ -1,5 +1,5 @@
 'use strict';
-const assert = require('assert');
 
-// Accessing module.parent should not be falsy.
-assert.ok(module.parent)
+if(!module.parent) {
+    setImmediate(() => {});
+}
diff --git a/test/parallel/test-module-parent-setter-deprecation.js b/test/parallel/test-module-parent-setter-deprecation.js
index f3efd89653cc8b..fb3a3cb78cb60a 100644
--- a/test/parallel/test-module-parent-setter-deprecation.js
+++ b/test/parallel/test-module-parent-setter-deprecation.js
@@ -1,5 +1,3 @@
-// Flags: --pending-deprecation
-
 'use strict';
 const common = require('../common');