America/Sao_Paulo datetime behavior is wrong when debug mode is OFF

Our current president has decided to cancel DST in Brazil this year. This means that since November 4th the timezone is being returned incorrectly (UTC -2 instead of -3).

I tried to use some libs to solve this problem:

"date-fns": "^2.6.0",
"date-fns-tz": "^1.0.8",
"moment": "^2.24.0",
"moment-timezone": "^0.5.27",

But I couldn’t.

I also learned that React Native has 2 types of environments to run JS: V8 from Chrome when Debug Mode is ON and device’s JavascriptCore when Debug Mode is OFF.

I’ve noticed that’s influences directly in the timezone behavior, since when Debug Mode is ON, there’s no problem with timezone at all using any of those libraries above.

I’ve also tried to solve this by installing "jsc-android": "241213.x.x" with all gradle config and stuff, but the timezone stills incorrect.

I can’t find a solution to make timezone works as expected.

---

React Native version:

React Native Environment Info:
    System:
      OS: macOS 10.14.6
      CPU: (4) x64 Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
      Memory: 111.66 MB / 8.00 GB
      Shell: 5.3 - /bin/zsh
    Binaries:
      Node: 10.15.1 - /usr/local/bin/node
      Yarn: 1.13.0 - /usr/local/bin/yarn
      npm: 6.4.1 - /usr/local/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.4, macOS 10.14, tvOS 12.4, watchOS 5.3
      Android SDK:
        API Levels: 21, 23, 27, 28, 29
        Build Tools: 23.0.1, 25.0.0, 25.0.2, 26.0.1, 26.0.2, 27.0.3, 28.0.2, 28.0.3, 29.0.0
        System Images: android-28 | Google APIs Intel x86 Atom, android-28 | Google Play Intel x86 Atom
    IDEs:
      Android Studio: 3.4 AI-183.6156.11.34.5692245
      Xcode: 10.3/10G8 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.8.3 => 16.8.3 
      react-native: 0.59.10 => 0.59.10 
    npmGlobalPackages:
      react-native-cli: 2.0.1
      react-native-git-upgrade: 0.2.7

Steps To Reproduce

import React, { Component } from 'react'
import { Text } from 'react-native'
import { parseISO } from 'date-fns'
import { zonedTimeToUtc } from 'date-fns-tz'

render(){
   const parsedDate = parseISO('2019-11-15 20:00:00');
   const znDate = zonedTimeToUtc(parsedDate, 'America/Sao_Paulo');

   return <Text>{`Date: ${znDate}`}</Text>
  // returns  Date: Fri Nov 15 2019 20:00:00 GTM-0200(-02)
}

Describe what you expected to happen:

   Date: Fri Nov 15 2019 20:00:00 GTM-0300(-03)

[radko93]

You can try using V8 engine (that’s possible now) or maybe try hermes? I know it’s not a real fix.

[radko93]

You can look here https://github.com/Kudo/react-native-v8#readme I would suggest that you open an issue on JSC as this will not be fixed in React Native directly probably?