Flow: Suppress "Flow is initializing"

[JakeCooper]

It would be great if there was a config option to remove this message. Its rather disruptive to the build process.

[gabelevi]

What build system are you using? You could ignore stderr I suppose, but it would be nice if either flow or the build system handled this more gracefully

[jamiebuilds]

Why would this ever show up more than once? Why would this ever show up more than once? Why would this ever show up more than once? Why would this ever show up more than once?

[JakeCooper]

@gabelevi We're using Webpack, and we only seem to get this spam once when it starts up. Not the end of the world, but we usually want to keep everything as clean as possible :).

[gabelevi]

Oh actually this isn't a Windows issue, this happens for everyone. Flow is trying to do a \r sort of thing to show a spinner while flow status waits for the Flow server to finish initializing or rechecking.

At the very least, if we should check Unix.isatty before clearing the line. And we probably shouldn't print status messages at all.

[mroch]

@gabelevi https://github.com/facebook/flow/blob/1f1c44269ee2a7473e68531d207154d067a742f0/hack/utils/tty.ml#L110

Perhaps webpack is doing something that makes fd 1 still look like a tty instead of a redirection, which would trick Unix.isatty.

[gabelevi]

@mroch - print_clear_line checks isatty, the logspew in the picture above is just coming from regular Utils.prerr_endlinef.