util: preserve length of deprecated functions

PR-URL: #57806
Reviewed-By: Jordan Harband <ljharb@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>

Author: LiviaMedeiros

lib/internal/util.js

@@ -142,6 +142,12 @@ function pendingDeprecate(fn, msg, code) {
 emitDeprecationWarning();
 returnReflectApply(fn,this,args);
 }
+
+ObjectDefineProperty(deprecated,'length',{
+__proto__: null,
+ ...ObjectGetOwnPropertyDescriptor(fn,'length'),
+});
+
 returndeprecated;
 }
 
@@ -180,6 +186,11 @@ function deprecate(fn, msg, code, useEmitSync) {
 deprecated.prototype=fn.prototype;
 }
 
+ObjectDefineProperty(deprecated,'length',{
+__proto__: null,
+ ...ObjectGetOwnPropertyDescriptor(fn,'length'),
+});
+
 returndeprecated;
 }
 

test/parallel/test-util-deprecate.js

@@ -1,3 +1,4 @@
+// Flags: --expose-internals
 'use strict';
 
 require('../common');
@@ -6,9 +7,27 @@ require('../common');
 
 constassert=require('assert');
 constutil=require('util');
+constinternalUtil=require('internal/util');
 
 constexpectedWarnings=newMap();
 
+// Deprecated function length is preserved
+for(constfnof[
+function(){},
+function(a){},
+function(a,b,c){},
+function(...args){},
+function(a,b,c, ...args){},
+()=>{},
+(a)=>{},
+(a,b,c)=>{},
+(...args)=>{},
+(a,b,c, ...args)=>{},
+]){
+assert.strictEqual(util.deprecate(fn).length,fn.length);
+assert.strictEqual(internalUtil.pendingDeprecate(fn).length,fn.length);
+}
+
 // Emits deprecation only once if same function is called.
 {
 constmsg='fhqwhgads';