Flow: Support additional export-from statement proposal

[ludofischer]

A.js:

export default 5;

B.js:

export a from './A';

Unexpected identifier error:

src/B.js:2
  2: export a from './A';
            ^ Unexpected identifier

Flow 0.17

[samwgoldman]

Is this syntax valid ES2015? I'm not seeing a production in the spec for this. The only production that has a _FromClause_ doesn't appear to permit a simple identifier as the _ExportClause_.

Do you have existing code that uses this syntax? How is it compiled?

[samwgoldman]

OK, so this seems to be a ES2016 proposed syntax from Facebook's own @leebyron. I don't think Flow has an established rule about what stage proposals we'll implement, but stage 1 seems a bit early to me. Looks like this one might hit stage 2 soon. I imagine this feature will have plenty of support internally to push it through :-)

[samwgoldman]

This is the same issue as #916. Linking the issues so we can close them all when a fix lands.

[GuillaumeLeclerc]

How is the state of that issue ?

[lgraziani2712]

Still fails on v0.33.0

[hiroppy]

+1

[jyane]

:+1:

[renatorib]

+1

[xareelee]

+1

[sibelius]

the same still happens on 0.44

[rohmanhm]

@sibelius please take a look this comment https://github.com/facebook/flow/issues/916#issuecomment-179849998

[sibelius]

@rohmanhm https://github.com/facebook/flow/issues/916#issuecomment-179849998 does not solve

export a from './A';

[SFantasy]

the same on 0.53

[sonaye]

Anybody faces the issue where suppress comments don't work for this case?

[asolove]

What is the error you're seeing that suppress comments aren't preventing? Is the error getting attached to a different line in the source?

[sonaye]

@asolove The flow error related to transform-export-extensions not being fully supported yet, it's the same line.

Error: src/configs/lib.js:42
 43: export axios from 'axios';
            ^^^^^ Unexpected identifier

and of course suppress_comment=\\(.\\|\n\\)*\\flow-disable-next-line.

[vkurchatkin]

You can't suppress parsing errors

[sonaye]

@vkurchatkin Got it, we wait till support for it lands then.

[Diokuz]

Same for 0.58.0

[silvenon]

This is a completely acceptable workaround:

export { default as a } from './a';

[sibelius]

can we add an option for this

https://github.com/facebook/flow/issues/916#issuecomment-310114962

much like

esproposal.export_star_as=enabled ?

[salisbury-espinosa]

Same for 0.68.0