adds deprication warning to errname()

doc/api/deprecations.md

@@ -2230,6 +2230,13 @@ like `dns.lookup(false)` due to backward compatibility.
 This behavior is undocumented and is thought to be unused in real world apps.
 It will become an error in future versions of Node.js.
 
+<a id="DEP0XXX"></a>
+### DEP0XXX: process.binding('uv').errname() private API
+
+Type: Documentation-only (supports [`--pending-deprecation`][])
+
+
+
 [`--pending-deprecation`]: cli.html#cli_pending_deprecation
 [`Buffer.allocUnsafeSlow(size)`]: buffer.html#buffer_class_method_buffer_allocunsafeslow_size
 [`Buffer.from(array)`]: buffer.html#buffer_class_method_buffer_from_array

src/env.cc

@@ -134,6 +134,7 @@ Environment::Environment(IsolateData* isolate_data,
       printed_error_(false),
       abort_on_uncaught_exception_(false),
       emit_env_nonstring_warning_(true),
+      emit_err_name_warning_(true),
       makecallback_cntr_(0),
       should_abort_on_uncaught_toggle_(isolate_, 1),
       trace_category_state_(isolate_, kTraceCategoryCount),

src/env.h

@@ -842,6 +842,11 @@ class Environment {
     emit_env_nonstring_warning_ = false;
     return current_value;
   }
+  inline bool EmitErrNameWarning() {
+    bool current_value = emit_err_name_warning_;
+    emit_err_name_warning_ = false;
+    return current_value;
+  }
 
   typedef void (*native_immediate_callback)(Environment* env, void* data);
   // cb will be called as cb(env, data) on the next event loop iteration.
@@ -929,6 +934,7 @@ class Environment {
   bool printed_error_;
   bool abort_on_uncaught_exception_;
   bool emit_env_nonstring_warning_;
+  bool emit_err_name_warning_;
   size_t makecallback_cntr_;
   std::vector<double> destroy_async_id_list_;
 

src/uv.cc

@@ -39,10 +39,17 @@ using v8::String;
 using v8::Value;
 
 
-// TODO(joyeecheung): deprecate this function in favor of
-// lib/util.getSystemErrorName()
 void ErrName(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
+  if (env->options()->pending_deprecation && env->EmitErrNameWarning()) {
+    if (ProcessEmitDeprecationWarning(
+        env,
+        "Directly calling process.binding('uv').errname(<val>) is being"
+        " deprecated. "
+        "Please make sure to use util.getSystemErrorName() instead.",
+        "DEP0XXX").IsNothing())
+    return;
+  }
   int err;
   if (!args[0]->Int32Value(env->context()).To(&err)) return;
   CHECK_LT(err, 0);

test/parallel/test-err-name-deprecation.js

@@ -0,0 +1,13 @@
+'use strict';
+const common = require('../common');
+
+// Flags: --pending-deprecation
+
+common.expectWarning(
+  'DeprecationWarning',
+  'Directly calling process.binding(\'uv\').errname(<val>) is being ' +
+  'deprecated. Please make sure to use util.getSystemErrorName() instead.',
+  'DEP0XXX'
+);
+
+process.binding('uv').errname(-1);