Upgrading from `@babel/parser@7.3.3` to `7.3.4` causes segfault/parser errors on Node 6

Bug Report

Current Behavior Upgrading the Jest repo from @babel/parser@7.3.3 to @babel/parser@7.3.4 causes Node 6 to either seemingly stop transpiling (leading to syntax errors in every test) or just die with a segfault. I’ve spent most of today tweaking different versions in our lockfile to try to narrow down which version it regressed on, and I’m quite certain the issue is in 7.3.4 - I had 3 failures with it and 3 passes with 7.3.3 reverting between them with no other changes to the code.

You can see my adventure here: https://github.com/facebook/jest/pull/8014

Most of the time it just seemingly stops parsing correctly, but sometimes it leads to segfault. I’ve never seen it fail on node 8, 10 or 11.

Input Code

• REPL or Repo link if applicable: https://github.com/facebook/jest/pull/8011

You can see in that PR that the only change is using just @babel/parse@7.3.4, and it fails CI. Upgrading @babel/core as well makes no difference. CircleCI running Node 6 is the interesting CI - the other failures are either me cancelling builds or the CI provider cancelling redundant builds.

I’m sorry I’m not able to reduce it more - it happens locally for me as well on Node 6 (but not all the time) after a few minutes running the tests. Hopefully this is enough information for you to investigate. It’s at least isolated to a patch release of a single package.

Expected behavior/code I expect it to not fail 😃

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

https://github.com/facebook/jest/blob/ae8280f7b009c141b81576171ee784d336d09800/babel.config.js

// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.

module.exports = {
  babelrcRoots: ['examples/*'],
  overrides: [
    {
      presets: ['@babel/preset-flow'],
      test: '**/*.js',
    },
    {
      plugins: [
        'babel-plugin-typescript-strip-namespaces',
        require.resolve(
          './scripts/babel-plugin-jest-replace-ts-export-assignment.js'
        ),
      ],
      presets: ['@babel/preset-typescript'],
      test: /\.tsx?$/,
    },
  ],
  plugins: [
    ['@babel/plugin-transform-modules-commonjs', {allowTopLevelThis: true}],
    '@babel/plugin-transform-strict-mode',
  ],
  presets: [
    [
      '@babel/preset-env',
      {
        shippedProposals: true,
        targets: {node: 6},
      },
    ],
  ],
};

Environment

• Babel version(s): core@7.3.3, parser@7.3.4
• Node/npm version: Node 6, yarn 1.13.0
• OS: macOS, but CI is Linux
• Monorepo: Yes, Yarn Workspaces
• How you are using Babel: babel-jest

Additional context/Screenshots Stopped transpiling: https://circleci.com/gh/facebook/jest/54093 Segfault: https://circleci.com/gh/facebook/jest/54414

[danez]

I will have a look. There weren’t that many changes between this two versions.

My guess is that the segfault is coming from jest which gets overwhelmed when thousands of tests fail. I experienced this (or at least similar behavior) also in babel when I make stupid changes that make every test explode.

Never the less will look into the Syntax errors.

[nicolo-ribaudo]

Note that reducing memory consumption is still a goal, and we will gladly accept PRs