From 2fb3d5153f66b5c455a3d554b80a874ebc7d9314 Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Mon, 11 Sep 2023 16:44:10 +0200
Subject: [PATCH 1/3] util: runtime deprecate `promisify`-ing a function
 returning a `Promise`

---
 lib/internal/util.js                 |  6 ++++--
 test/parallel/test-util-promisify.js | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/lib/internal/util.js b/lib/internal/util.js
index 3586084ba7b8bd..48724374b0eec0 100644
--- a/lib/internal/util.js
+++ b/lib/internal/util.js
@@ -63,7 +63,7 @@ const {
   sleep: _sleep,
   toUSVString: _toUSVString,
 } = internalBinding('util');
-const { isNativeError } = internalBinding('types');
+const { isNativeError, isPromise } = internalBinding('types');
 const { getOptionValue } = require('internal/options');
 
 const noCrypto = !process.versions.openssl;
@@ -409,7 +409,9 @@ function promisify(original) {
           resolve(values[0]);
         }
       });
-      ReflectApply(original, this, args);
+      if (isPromise(ReflectApply(original, this, args))) {
+        process.emitWarning('Calling promisify on a function that returns a Promise is likely a mistake.');
+      }
     });
   }
 
diff --git a/test/parallel/test-util-promisify.js b/test/parallel/test-util-promisify.js
index 0fc2d650ee9272..82e7218eabcc46 100644
--- a/test/parallel/test-util-promisify.js
+++ b/test/parallel/test-util-promisify.js
@@ -7,6 +7,21 @@ const vm = require('vm');
 const { promisify } = require('util');
 const { customPromisifyArgs } = require('internal/util');
 
+{
+  const warningHandler = common.mustNotCall();
+  process.on('warning', warningHandler);
+  function foo() {}
+  foo.constructor = (async () => {}).constructor;
+  promisify(foo);
+  process.off('warning', warningHandler);
+}
+
+common.expectWarning('Warning', 'Calling promisify on a function that returns a Promise is likely a mistake.');
+promisify(async (callback) => { callback(); })().then(common.mustCall(() => {
+  common.expectWarning('Warning', 'Calling promisify on a function that returns a Promise is likely a mistake.');
+  promisify(async () => {})().then(common.mustNotCall());
+}));
+
 const stat = promisify(fs.stat);
 
 {

From f9726f9e647528b5cf2a86309baae6eff32f1d25 Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Sat, 16 Sep 2023 12:02:30 +0200
Subject: [PATCH 2/3] fixup! util: runtime deprecate `promisify`-ing a function
 returning a `Promise`

---
 lib/internal/util.js                 |  3 ++-
 test/parallel/test-util-promisify.js | 12 ++++++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/internal/util.js b/lib/internal/util.js
index 48724374b0eec0..3d63b983a2cbed 100644
--- a/lib/internal/util.js
+++ b/lib/internal/util.js
@@ -410,7 +410,8 @@ function promisify(original) {
         }
       });
       if (isPromise(ReflectApply(original, this, args))) {
-        process.emitWarning('Calling promisify on a function that returns a Promise is likely a mistake.');
+        process.emitWarning('Calling promisify on a function that returns a Promise is likely a mistake.',
+                            'DeprecationWarning', 'DEP0174');
       }
     });
   }
diff --git a/test/parallel/test-util-promisify.js b/test/parallel/test-util-promisify.js
index 82e7218eabcc46..e2318a4973b972 100644
--- a/test/parallel/test-util-promisify.js
+++ b/test/parallel/test-util-promisify.js
@@ -16,9 +16,17 @@ const { customPromisifyArgs } = require('internal/util');
   process.off('warning', warningHandler);
 }
 
-common.expectWarning('Warning', 'Calling promisify on a function that returns a Promise is likely a mistake.');
+common.expectWarning(
+  'DeprecationWarning',
+  'Calling promisify on a function that returns a Promise is likely a mistake.',
+  'DEP0174');
 promisify(async (callback) => { callback(); })().then(common.mustCall(() => {
-  common.expectWarning('Warning', 'Calling promisify on a function that returns a Promise is likely a mistake.');
+  // We must add the second `expectWarning` call in the `.then` handler, when
+  // the first warning has already been triggered.
+  common.expectWarning(
+    'DeprecationWarning',
+    'Calling promisify on a function that returns a Promise is likely a mistake.',
+    'DEP0174');
   promisify(async () => {})().then(common.mustNotCall());
 }));
 

From ad10dde08a095039acce8f10118ae7383f6110fb Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Sat, 16 Sep 2023 12:05:46 +0200
Subject: [PATCH 3/3] fixup! fixup! util: runtime deprecate `promisify`-ing a
 function returning a `Promise`

---
 doc/api/deprecations.md | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/doc/api/deprecations.md b/doc/api/deprecations.md
index 7cabc90b278fd8..8b9c9e59adc7b5 100644
--- a/doc/api/deprecations.md
+++ b/doc/api/deprecations.md
@@ -3387,12 +3387,15 @@ Consider using alternatives such as the [`mock`][] helper function.
 
 <!-- YAML
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/49609
+    description: Runtime deprecation.
   - version: REPLACEME
     pr-url: https://github.com/nodejs/node/pull/49647
     description: Documentation-only deprecation.
 -->
 
-Type: Documentation-only
+Type: Runtime
 
 Calling [`util.promisify`][] on a function that returns a <Promise> will ignore
 the result of said promise, which can lead to unhandled promise rejections.