Latest release of Gatsby@2.0.0-rc.9 seems to ignore custom .babelrc

[Calderis]

Description

In order to accept decorator (@things) babel require plugin @babel/plugin-proposal-decorators so I create my own .babelrc file based on Gatsby's doc.
But, latest release of Gatsby next seems to ignore custom .babelrc file.

Steps to reproduce

By updating to the latest release with "gatsby": "next" in package.json, it fails on each compilation . But by specifying "gatsby": "2.0.0-rc.8" it works back.

custom .babelrc I use

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "loose": true,
        "modules": false,
        "useBuiltIns": "usage",
        "shippedProposals": true,
        "targets": {
          "browsers": [">0.25%", "not dead"],
        },
      },
    ],
    [
      "@babel/preset-react",
      {
        "useBuiltIns": true,
        "pragma": "React.createElement",
      },
    ],
  ],
  "plugins": [
    "babel-plugin-macros",
    ["@babel/plugin-proposal-decorators", { "legacy": true }],
    ["@babel/plugin-proposal-class-properties", { "loose": true }],
    ["@babel/plugin-transform-runtime", { "helpers": true, "regenerator": true }],
    "@babel/plugin-syntax-dynamic-import"
  ],
}

Expected result

Custom .babelrc file seems to be taken into account in version lower than 2.0.0-rc.9.

Actual result

On Gatsby 2.0.0-rc.9, custom .babelrc is ignored. You can still specify rules in custom webpack configuration.

Environment

  
  System:
    OS: macOS High Sierra 10.13.6
    CPU: x64 Intel(R) Core(TM) i5-5257U CPU @ 2.70GHz
    Shell: 5.3 - /bin/zsh
  Binaries:
    Node: 8.9.0 - ~/.nvm/versions/node/v8.9.0/bin/node
    Yarn: 1.7.0 - /usr/local/bin/yarn
    npm: 5.5.1 - ~/.nvm/versions/node/v8.9.0/bin/npm
  Browsers:
    Chrome: 68.0.3440.106
    Firefox: 61.0.1
    Safari: 11.1.2
  npmPackages:
    gatsby: next => 2.0.0-rc.9 
    gatsby-link: next => 2.0.0-rc.2 
    gatsby-plugin-create-client-paths: next => 2.0.0-rc.1 
    gatsby-plugin-google-analytics: next => 2.0.0-rc.1 
    gatsby-plugin-meta-redirect: ^1.0.4 => 1.1.0 
    gatsby-plugin-postcss-sass: next => 1.0.0-beta.6 
    gatsby-plugin-react-helmet: next => 3.0.0-rc.1 
    gatsby-plugin-sass: next => 2.0.0-rc.1 
    gatsby-remark-copy-linked-files: next => 2.0.0-rc.1 
    gatsby-source-filesystem: next => 2.0.1-rc.1 
    gatsby-transformer-json: next => 2.1.1-rc.1 

[DSchau]

@Calderis thanks for the thorough reproduction steps. Would you be able to create a repo demonstrating the issue so that we can take a look and debug?

Thank you!

[DSchau]

Actually, ignore the above 😅

Looks like the PR @pieh referenced is the ticket. Once that's (#7865) merged, this should continue to work like you'd expect.

Thanks!