1 files changed, 76 insertions, 16 deletions

diff --git a/lib/internal/process/promises.js b/lib/internal/process/promises.js
index f3e118e2ce..95161ac7a8 100644
--- a/lib/internal/process/promises.js
+++ b/lib/internal/process/promises.js
@@ -1,6 +1,10 @@
 'use strict';
 
-const { safeToString } = internalBinding('util');
+const { Object } = primordials;
+
+const {
+  safeToString
+} = internalBinding('util');
 const {
   tickInfo,
   promiseRejectEvents: {
@@ -9,7 +13,8 @@ const {
     kPromiseResolveAfterResolved,
     kPromiseRejectAfterResolved
   },
-  setPromiseRejectCallback
+  setPromiseRejectCallback,
+  triggerFatalException
 } = internalBinding('task_queue');
 
 // *Must* match Environment::TickInfo::Fields in src/env.h.
@@ -20,6 +25,15 @@ const pendingUnhandledRejections = [];
 const asyncHandledRejections = [];
 let lastPromiseId = 0;
 
+const states = {
+  none: 0,
+  warn: 1,
+  strict: 2,
+  default: 3
+};
+
+let state;
+
 function setHasRejectionToWarn(value) {
   tickInfo[kHasRejectionToWarn] = value ? 1 : 0;
 }
@@ -29,6 +43,10 @@ function hasRejectionToWarn() {
 }
 
 function promiseRejectHandler(type, promise, reason) {
+  if (state === undefined) {
+    const { getOptionValue } = require('internal/options');
+    state = states[getOptionValue('--unhandled-rejections') || 'default'];
+  }
   switch (type) {
     case kPromiseRejectWithNoHandler:
       unhandledRejection(promise, reason);
@@ -59,6 +77,7 @@ function unhandledRejection(promise, reason) {
     uid: ++lastPromiseId,
     warned: false
   });
+  // This causes the promise to be referenced at least for one tick.
   pendingUnhandledRejections.push(promise);
   setHasRejectionToWarn(true);
 }
@@ -85,14 +104,16 @@ function handledRejection(promise) {
 
 const unhandledRejectionErrName = 'UnhandledPromiseRejectionWarning';
 function emitWarning(uid, reason) {
-  // eslint-disable-next-line no-restricted-syntax
-  const warning = new Error(
+  if (state === states.none) {
+    return;
+  }
+  const warning = getError(
+    unhandledRejectionErrName,
     'Unhandled promise rejection. This error originated either by ' +
-    'throwing inside of an async function without a catch block, ' +
-    'or by rejecting a promise which was not handled with .catch(). ' +
-    `(rejection id: ${uid})`
+      'throwing inside of an async function without a catch block, ' +
+      'or by rejecting a promise which was not handled with .catch(). ' +
+      `(rejection id: ${uid})`
   );
-  warning.name = unhandledRejectionErrName;
   try {
     if (reason instanceof Error) {
       warning.stack = reason.stack;
@@ -108,7 +129,7 @@ function emitWarning(uid, reason) {
 
 let deprecationWarned = false;
 function emitDeprecationWarning() {
-  if (!deprecationWarned) {
+  if (state === states.default && !deprecationWarned) {
     deprecationWarned = true;
     process.emitWarning(
       'Unhandled promise rejections are deprecated. In the future, ' +
@@ -133,18 +154,57 @@ function processPromiseRejections() {
   while (len--) {
     const promise = pendingUnhandledRejections.shift();
     const promiseInfo = maybeUnhandledPromises.get(promise);
-    if (promiseInfo !== undefined) {
-      promiseInfo.warned = true;
-      const { reason, uid } = promiseInfo;
-      if (!process.emit('unhandledRejection', reason, promise)) {
-        emitWarning(uid, reason);
-      }
-      maybeScheduledTicks = true;
+    if (promiseInfo === undefined) {
+      continue;
+    }
+    promiseInfo.warned = true;
+    const { reason, uid } = promiseInfo;
+    if (state === states.strict) {
+      fatalException(reason);
     }
+    if (!process.emit('unhandledRejection', reason, promise) ||
+        // Always warn in case the user requested it.
+        state === states.warn) {
+      emitWarning(uid, reason);
+    }
+    maybeScheduledTicks = true;
   }
   return maybeScheduledTicks || pendingUnhandledRejections.length !== 0;
 }
 
+function getError(name, message) {
+  // Reset the stack to prevent any overhead.
+  const tmp = Error.stackTraceLimit;
+  Error.stackTraceLimit = 0;
+  // eslint-disable-next-line no-restricted-syntax
+  const err = new Error(message);
+  Error.stackTraceLimit = tmp;
+  Object.defineProperty(err, 'name', {
+    value: name,
+    enumerable: false,
+    writable: true,
+    configurable: true,
+  });
+  return err;
+}
+
+function fatalException(reason) {
+  let err;
+  if (reason instanceof Error) {
+    err = reason;
+  } else {
+    err = getError(
+      'UnhandledPromiseRejection',
+      'This error originated either by ' +
+        'throwing inside of an async function without a catch block, ' +
+        'or by rejecting a promise which was not handled with .catch().' +
+        ` The promise rejected with the reason "${safeToString(reason)}".`
+    );
+    err.code = 'ERR_UNHANDLED_REJECTION';
+  }
+  triggerFatalException(err, true /* fromPromise */);
+}
+
 function listenForRejections() {
   setPromiseRejectCallback(promiseRejectHandler);
 }