SyntaxError: Expected atom at position 2 \p{Script_Ex

Bug Report

Current Behavior

> babel . --out-dir dist

SyntaxError: Expected atom at position 2
    \p{Script_Ex
      ^
    at bail (/home/shm/dpp-query-ws/node_modules/regjsparser/parser.js:1093:13)
    at parseTerm (/home/shm/dpp-query-ws/node_modules/regjsparser/parser.js:486:9)
    at parseAlternative (/home/shm/dpp-query-ws/node_modules/regjsparser/parser.js:457:21)
    at parseDisjunction (/home/shm/dpp-query-ws/node_modules/regjsparser/parser.js:437:16)
    at parse (/home/shm/dpp-query-ws/node_modules/regjsparser/parser.js:1108:18)
    at rewritePattern (/home/shm/dpp-query-ws/node_modules/regexpu-core/rewrite-pattern.js:324:15)
    at PluginPass.RegExpLiteral (/home/shm/dpp-query-ws/node_modules/@babel/plugin-transform-unicode-regex/lib/index.js:50:51)
    at newFn (/home/shm/dpp-query-ws/node_modules/@babel/traverse/lib/visitors.js:193:21)
    at NodePath._call (/home/shm/dpp-query-ws/node_modules/@babel/traverse/lib/path/context.js:53:20)
    at NodePath.call (/home/shm/dpp-query-ws/node_modules/@babel/traverse/lib/path/context.js:40:17)

Input Code

• REPL or Repo link if applicable:

var your => (code) => here;

Expected behavior/code Successful transpiled code

Babel Configuration (.babelrc, package.json, cli command) package.json

"devDependencies": {
    "@babel/cli": "^7.1.2",
    "@babel/core": "^7.1.2",
    "@babel/node": "^7.0.0",
    "@babel/plugin-proposal-object-rest-spread": "^7.0.0",
    "@babel/preset-env": "^7.1.0",
    "@babel/preset-flow": "^7.0.0",
    "nodemon": "^1.18.4"
  }

babel.config.js

module.exports = {
  "presets": ["@babel/preset-env","@babel/preset-flow"],
  "plugins": [
    "@babel/plugin-proposal-object-rest-spread"
  ]
}

Environment

• Babel version(s): [e.g. v6.0.0, v7.0.0-beta.34]
• Node/npm version: Node 8.12.0/npm 6.4.1
• OS: Ubuntu 16.04.4 LTS
• Monorepo
• How you are using Babel: [e.g. cli, register, loader] cli

  "build": "babel . --out-dir dist"
  

[jasonk]

So I’ve managed to narrow this down. I’m not certain what the “real” fix for it is, but I have some ideas, (and a workaround that is working for me )…

TL;DR - Workaround:

[ '@babel/preset-env', {
  include : [ '@babel/plugin-proposal-unicode-property-regex' ],
  exclude : [ '@babel/plugin-transform-unicode-regex' ],
} ],

When it fails for me there are two unicode regex related plugins that have been enabled by preset-env: transform-unicode-regex and proposal-unicode-property-regex. They are both doing effectively the exact same thing, using rewritePattern from regexpu-core to transform the regex into an equivalent ES5 regex.

However, only proposal-unicode-property-regex is passing the option unicodePropertyEscape: true when it calls rewritePattern, transform-unicode-regex is not, which causes regjsparser to choke on \p{...} and \P{...} patterns.

Unfortunately I don’t understand the Babel internals well enough to determine:

• Why preset-env decided that both of these plugins were needed when the only difference between them is that one of them understands \p/\P and the other doesn’t.
• How it determines what order to apply the plugins in. Even though they are nearly identical, it seems as though it would work fine if proposal-unicode-property-regex were applied first, since it would transform the problematic escapes into something that transform-unicode-regex wouldn’t have issues with.

If it helps, here is my preset-env debug output:

@babel/preset-env: `DEBUG` option

Using targets:
{
  "android": "67",
  "chrome": "72",
  "edge": "15",
  "firefox": "60",
  "ie": "11",
  "ios": "11",
  "opera": "46",
  "safari": "11",
  "samsung": "6.2"
}

Using modules transform: false

Using plugins:
  transform-template-literals { "android":"67", "ie":"11", "ios":"11", "safari":"11" }
  transform-literals { "android":"67", "ie":"11" }
  transform-function-name { "android":"67", "edge":"15", "ie":"11" }
  transform-arrow-functions { "android":"67", "ie":"11" }
  transform-block-scoped-functions { "android":"67" }
  transform-classes { "android":"67", "ie":"11" }
  transform-object-super { "android":"67", "ie":"11" }
  transform-shorthand-properties { "android":"67", "ie":"11" }
  transform-duplicate-keys { "android":"67", "ie":"11" }
  transform-computed-properties { "android":"67", "ie":"11" }
  transform-for-of { "android":"67", "ie":"11" }
  transform-sticky-regex { "android":"67", "ie":"11" }
  transform-dotall-regex { "android":"67", "edge":"15", "firefox":"60", "ie":"11", "ios":"11", "opera":"46", "safari":"11", "samsung":"6.2" }
  transform-unicode-regex { "android":"67", "ie":"11", "ios":"11", "safari":"11" }
  transform-spread { "android":"67", "ie":"11" }
  transform-parameters { "android":"67", "edge":"15", "ie":"11" }
  transform-destructuring { "android":"67", "ie":"11" }
  transform-block-scoping { "android":"67", "ie":"11" }
  transform-typeof-symbol { "android":"67", "ie":"11" }
  transform-new-target { "android":"67", "ie":"11" }
  transform-regenerator { "android":"67", "ie":"11" }
  transform-exponentiation-operator { "android":"67", "ie":"11" }
  transform-async-to-generator { "android":"67", "ie":"11" }
  proposal-async-generator-functions { "android":"67", "edge":"15", "ie":"11", "ios":"11", "opera":"46", "safari":"11", "samsung":"6.2" }
  proposal-object-rest-spread { "android":"67", "edge":"15", "ie":"11", "ios":"11", "opera":"46", "safari":"11", "samsung":"6.2" }
  proposal-unicode-property-regex { "android":"67", "edge":"15", "firefox":"60", "ie":"11", "ios":"11", "opera":"46", "safari":"11", "samsung":"6.2" }
  proposal-json-strings { "android":"67", "edge":"15", "firefox":"60", "ie":"11", "ios":"11", "opera":"46", "safari":"11", "samsung":"6.2" }
  proposal-optional-catch-binding { "android":"67", "edge":"15", "ie":"11", "ios":"11", "opera":"46", "safari":"11", "samsung":"6.2" }
  transform-named-capturing-groups-regex { "android":"67", "edge":"15", "firefox":"60", "ie":"11", "ios":"11", "opera":"46", "safari":"11", "samsung":"6.2" }

[jridgewell]

Just enabling the preset-es2015 causes it… Try checking/unchecking the box in https://babeljs.io/repl/build/master#?babili=false&browsers=Safari >%3D 8&build=&builtIns=false&spec=false&loose=false&code_lz=EQMwlgNgpgcghgWysAdAJygBwnAxlACgHoCAdTAbwBkIBfASjMqoFcGiWBzAGgAIByACQBGXoIBM_ekA&debug=false&forceAllTransforms=false&shippedProposals=false&circleciRepo=&evaluate=true&fileSize=false&timeTravel=false&sourceType=module&lineWrap=true&presets=es2015&prettier=false&targets=&version=7.3.4