gatsby: React 17 new JSX Transform: ReferenceError: React is not defined

Description

Gatsby 2.28.1 will throw a ReferenceError: React is not defined if React is not imported on top of the file, but the new JSX Transform (built-in in Gatsby since 2.24) supports files with JSX without a React Import.

Steps to reproduce

I couldn’t reproduce this in CodeSandbox but you should easily reproduce this by rendering a component that does not import React.

Expected result

Should not throw the error and allow components without a React import to work normally

Actual result

What happened. It happens in both development and build mode The output JS file does not have any React reference:

__webpack_require__.r(__webpack_exports__);
/* WEBPACK VAR INJECTION */(function(__react_refresh_utils__) {/* harmony export (binding) */ __webpack_require__.d(__webpack_exports__, "ExplorerTemplate", function() { return ExplorerTemplate; });
__webpack_require__.$Refresh$.runtime = __webpack_require__(/*! ./node_modules/react-refresh/runtime.js */ "./node_modules/react-refresh/runtime.js");
__webpack_require__.$Refresh$.setup(module.i);

var _jsxFileName = "/home/bartmr/Documents/unnamed-too/client-side/web-app/src/components/templates/explorer/explorer-template.tsx";
function ExplorerTemplate() {
  return /*#__PURE__*/React.createElement("div", {
    __self: this,
    __source: {
      fileName: _jsxFileName,
      lineNumber: 7,
      columnNumber: 5
    }
  });
}
_c = ExplorerTemplate;

var _c;

__webpack_require__.$Refresh$.register(_c, "ExplorerTemplate");

const currentExports = __react_refresh_utils__.getModuleExports(module.i);
__react_refresh_utils__.registerExportsForReactRefresh(currentExports, module.i);

if (true) {
  const isHotUpdate = !!module.hot.data;
  const prevExports = isHotUpdate ? module.hot.data.prevExports : null;

  if (__react_refresh_utils__.isReactRefreshBoundary(currentExports)) {
    module.hot.dispose(
      /**
       * A callback to performs a full refresh if React has unrecoverable errors,
       * and also caches the to-be-disposed module.
       * @param {*} data A hot module data object from Webpack HMR.
       * @returns {void}
       */
      function hotDisposeCallback(data) {
        // We have to mutate the data object to get data registered and cached
        data.prevExports = currentExports;
      }
    );
    module.hot.accept(
      /**
       * An error handler to allow self-recovering behaviours.
       * @param {Error} error An error occurred during evaluation of a module.
       * @returns {void}
       */
      function hotErrorHandler(error) {
        if (
          false
        ) {}

        if (typeof __react_refresh_test__ !== 'undefined' && __react_refresh_test__) {
          if (window.onHotAcceptError) {
            window.onHotAcceptError(error.message);
          }
        }

        __webpack_require__.c[module.i].hot.accept(hotErrorHandler);
      }
    );

    if (isHotUpdate) {
      if (
        __react_refresh_utils__.isReactRefreshBoundary(prevExports) &&
        __react_refresh_utils__.shouldInvalidateReactRefreshBoundary(prevExports, currentExports)
      ) {
        module.hot.invalidate();
      } else {
        __react_refresh_utils__.enqueueUpdate(
          /**
           * A function to dismiss the error overlay after performing React refresh.
           * @returns {void}
           */
          function updateCallback() {
            if (
              false
            ) {}
          }
        );
      }
    }
  } else {
    if (isHotUpdate && __react_refresh_utils__.isReactRefreshBoundary(prevExports)) {
      module.hot.invalidate();
    }
  }
}
/* WEBPACK VAR INJECTION */}.call(this, __webpack_require__(/*! ./node_modules/@pmmmwh/react-refresh-webpack-plugin/lib/runtime/RefreshUtils.js */ "./node_modules/@pmmmwh/react-refresh-webpack-plugin/lib/runtime/RefreshUtils.js")))//# sourceURL=[module]
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Environment

It happens in both development and build mode It also happens in NodeJS 12

System: OS: Linux 4.15 Ubuntu 18.04.5 LTS (Bionic Beaver) CPU: (4) x64 Intel® Core™ i7-7500U CPU @ 2.70GHz Shell: 4.4.20 - /bin/bash Binaries: Node: 10.16.0 - ~/.nvm/versions/node/v10.16.0/bin/node npm: 6.9.0 - ~/.nvm/versions/node/v10.16.0/bin/npm Languages: Python: 2.7.17 - /usr/bin/python Browsers: Chrome: 87.0.4280.88 npmPackages: gatsby: ^2.28.1 => 2.28.1 gatsby-image: ^2.7.0 => 2.7.0 gatsby-plugin-manifest: ^2.8.0 => 2.8.0 gatsby-plugin-offline: ^3.6.0 => 3.6.0 gatsby-plugin-react-helmet: ^3.6.0 => 3.6.0 gatsby-plugin-robots-txt: ^1.5.3 => 1.5.3 gatsby-plugin-sass: ^2.7.0 => 2.7.0 gatsby-plugin-sharp: ^2.10.1 => 2.10.1 gatsby-plugin-sitemap: ^2.8.0 => 2.8.0 gatsby-plugin-svgr: 2.0.2 => 2.0.2 gatsby-plugin-webpack-bundle-analyser-v2: ^1.1.18 => 1.1.18 gatsby-source-filesystem: ^2.7.0 => 2.7.0 gatsby-transformer-sharp: ^2.8.0 => 2.8.0 npmGlobalPackages: gatsby-cli: 2.7.49

Possible solution:

I was able to go around this bug by adding this to gatsby-node.js:

exports.onCreateBabelConfig = ({ actions }) => {
  actions.setBabelPlugin({
    name: '@babel/plugin-transform-react-jsx',
    options: {
      runtime: 'automatic',
    },
  });
};