[wip] revert compling cache-dir and remove non standard code from cache-dir

[pieh]

#5637 might be to aggressive to transpile it - right now @babel/preset-env doesn't know it needs to polyfill Promise used in cache-dir, which breaks runtime in ie 11 ( #6103 )

This attempt just removes flow types and move cache-dir to same place it was before.

closes #6103
closes #6102

[pieh]

/cc @KyleAMathews @jquense

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[pieh]

Actually, because we don't use flow extensively in cache-dir, removing flow stuff manually from cache-dir would yield same result without need for "build" step for it - so I'll manually edit cache-dir to not contain flow and move it from src to root gatsby dir

[jquense]

It'd be cool if there was like an eslint plguin for only allowing stuff preset-env can compile, like nothing that isn't standardized or implemented

[pieh]

It'd be cool if there was like an eslint plguin for only allowing stuff preset-env can compile, like nothing that isn't standardized or implemented

I didn't find anything like that for eslint, but maybe we could add test to try to run babel on cache-dir with minimal config to catch changes that would add any non standard stuff?

[pieh]

@jquense how about something like pieh/gatsby@9a5b113...pieh:ie11-promise-test (proof of concept)
it would fail when there would be (for example) flow types:

 FAIL  packages\gatsby\cache-dir\__tests__\minimal-config.js
  × Builds cache-dir with minimal config (1085ms)

  ● Builds cache-dir with minimal config

    expect(received).toEqual(expected)

    Expected value to equal:
      ""
    Received:
      "{ SyntaxError: D:\\dev\\gatsby-v2\\packages\\gatsby\\cache-dir\\prefetcher.js: Unexpected token, expected \";\" (3:5)

      1 | // @flow
      2 |
    > 3 | type PrefetcherOptions = {
        |      ^
      4 |   fetchNextResource: () => ?Promise,
      5 | }
      6 |
        at _class.raise (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:3893:15)
        at _class.unexpected (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:5222:16)
        at _class.semicolon (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:5206:40)
        at _class.parseExpressionStatement (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:7635:10)
        at _class.parseStatementContent (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:7234:19)
        at _class.parseStatement (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:7115:17)
        at _class.parseBlockOrModuleBlockBody (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:7666:23)
        at _class.parseBlockBody (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:7653:10)
        at _class.parseTopLevel (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:7080:10)
        at _class.parse (D:\\dev\\gatsby-v2\\node_modules\\@babel\\parser\\lib\\index.js:8466:17)
      pos: 17,
      loc: Position { line: 3, column: 5 },
      code: 'BABEL_PARSE_ERROR' }
    "

      26 |
      27 |   spawn.on(`close`, function () {
    > 28 |     expect(stderr).toEqual(``)
      29 |     expect(stdout).toEqual(
      30 |       expect.stringMatching(`Successfully compiled`),
      31 |     )

      at ChildProcess.<anonymous> (packages/gatsby/cache-dir/__tests__/minimal-config.js:28:20)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 1 total
Snapshots:   0 total
Time:        2.695s

[KyleAMathews]

Looks good! This will fix #6102 as well once in.

[KyleAMathews]

Why revert this?

[pieh]

Maybe I don't need to revert this, I thought this needed something like transform-optional-chaining plugin. I'll re-check it.

[pieh]

Yeah, so after reverting and running my WIP test ( pieh/gatsby@9a5b113...pieh:ie11-promise-test ) for this:

$ jest minimal-config
 FAIL  packages\gatsby\cache-dir\__tests__\minimal-config.js
  × Builds cache-dir with minimal config (913ms)

  ● Builds cache-dir with minimal config

    expect(received).toEqual(expected)

    Expected value to equal:
      ""
    Received:
      "{ SyntaxError: D:\\dev\\gatsby-v2\\packages\\gatsby\\cache-dir\\json-store.js: Support for the experimental syntax 'optionalChaining' isn't currently
enabled (7:54):

       5 | import socketIo, { getStaticQueryData, getPageQueryData } from \"./socketIo\"
       6 |
    >  7 | const getPathFromProps = props => props.pageResources?.page?.path
         |                                                      ^
       8 |
       9 | class JSONStore extends React.Component {
      10 |   constructor(props) {

    Add @babel/plugin-proposal-optional-chaining (https://git.io/vb4Sk) to the 'plugins' section of your Babel config to enable transformation.

This was fine previously because I was applying same babel config used to build packages for cache-dir (which includes @babel/plugin-proposal-optional-chaining )

[m-allanson]

🙏 👍