Flow parser should support import.meta

[rtsao]

import.meta is a stage 3 proposal that has shipped in Chrome, Firefox, and Node 10. Flow should be able to parse this syntax.

https://flow.org/try/#0PQKgBAAgZgNg9gdzCYAoVBLAtgBzgJwBcA6LAU0IENiBXfGAbiA

[wchargin]

Implemented in #6958.

[wchargin]

Friendly ping on that PR. I know some folks were interested in this and
wouldn’t want the diff to go stale.

[mgtitimoli]

We didn't get a response from your previously friendly ping @wchargin, so I'm pinging again hoping we are gonna get some response now :)

[fredericgermain]

import.meta.url is the official way to have __dirname in ESM node implementation. ES6 Module support is very strict in node.
https://nodejs.org/docs/latest/api/esm.html

We can't migrate to modules while flow is not supporting it (flow-remove-types makes an error on this syntax too). Or we have to get around the __dirname variable.

[Kapelianovych]

It's not implemeted yet( Though import.meta is living standard already.

[unphased]

I cannot use flow because use of import.meta breaks flow parsing of the entire source file from that point forward...

Yes, I am using import.meta.url to obtain __dirname in node scripts.

[strager]

I use this ugly workaround to make both Flow and Node.js happy:

// $FlowFixMe
let __filename /*: string */ = url.fileURLToPath(import /*:: ("") */.meta.url);

I don't know if this works with flow-removes-types or Babel, though.

[ancms2600]

The above workaround didn't quite work for me but this does:

import { dirname } from 'path';
import { fileURLToPath } from 'url';
const __dirname/*:string*/ = dirname(fileURLToPath(/*::(*/import/*::('fs'):any)*/.meta.url)); // facebook/flow PR#6958