Bug Fix for Issue #17668 - Unused prototype objects from V8 FunctionTemplate initialization

src/env-inl.h

@@ -583,9 +583,11 @@ inline void Environment::ThrowUVException(int errorno,
 
 inline v8::Local<v8::FunctionTemplate>
     Environment::NewFunctionTemplate(v8::FunctionCallback callback,
-                                     v8::Local<v8::Signature> signature) {
+                                     v8::Local<v8::Signature> signature,
+                                     v8::ConstructorBehavior behavior) {
   v8::Local<v8::External> external = as_external();
-  return v8::FunctionTemplate::New(isolate(), callback, external, signature);
+  return v8::FunctionTemplate::New(isolate(), callback, external,
+                                   signature, 0, behavior);
 }
 
 inline void Environment::SetMethod(v8::Local<v8::Object> that,
@@ -605,7 +607,8 @@ inline void Environment::SetProtoMethod(v8::Local<v8::FunctionTemplate> that,
                                         const char* name,
                                         v8::FunctionCallback callback) {
   v8::Local<v8::Signature> signature = v8::Signature::New(isolate(), that);
-  v8::Local<v8::FunctionTemplate> t = NewFunctionTemplate(callback, signature);
+  v8::Local<v8::FunctionTemplate> t =
+      NewFunctionTemplate(callback, signature, v8::ConstructorBehavior::kThrow);
   // kInternalized strings are created in the old space.
   const v8::NewStringType type = v8::NewStringType::kInternalized;
   v8::Local<v8::String> name_string =

src/env.h

@@ -687,7 +687,9 @@ class Environment {
   inline v8::Local<v8::FunctionTemplate>
       NewFunctionTemplate(v8::FunctionCallback callback,
                           v8::Local<v8::Signature> signature =
-                              v8::Local<v8::Signature>());
+                              v8::Local<v8::Signature>(),
+                          v8::ConstructorBehavior behavior =
+                              v8::ConstructorBehavior::kAllow);
 
   // Convenience methods for NewFunctionTemplate().
   inline void SetMethod(v8::Local<v8::Object> that,

test/parallel/test-env-newprotomethod-remove-unnecessary-prototypes.js

@@ -0,0 +1,18 @@
+'use strict';
+require('../common');
+
+// This test ensures that unnecessary prototypes are no longer
+// being generated by Environment::NewFunctionTemplate.
+
+const assert = require('assert');
+
+[
+  process.binding('udp_wrap').UDP.prototype.bind6,
+  process.binding('tcp_wrap').TCP.prototype.bind6,
+  process.binding('udp_wrap').UDP.prototype.send6,
+  process.binding('tcp_wrap').TCP.prototype.bind,
+  process.binding('udp_wrap').UDP.prototype.close,
+  process.binding('tcp_wrap').TCP.prototype.open
+].forEach((binding, i) => {
+  assert.strictEqual('prototype' in binding, false, `Test ${i} failed`);
+});