There's a ticket for this now. https://ghc.haskell.org/trac/ghc/ticket/10021
Do add comments there, or they'll get lost.
But I think you are misunderstanding the proposal (which admittedly is not stated clearly). It only affects the error messages produced by GHC itself. There is no proposal to change the behaviour of the 'error' function.
Simon
| -----Original Message-----
| From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of
| Yitzchak Gale
| Sent: 27 January 2015 16:49
| To: Konstantine Rybnikov
| Cc: ghc-devs@haskell.org
| Subject: Re: Put "Error:" before error output
|
| -1
|
| There are common idioms that rely on the current behavior, so I think
| this would break a lot code.
|
| Examples:
|
| In command line programs, it is very common to use "error" for
| printing the usage message.
|
| Many programs use "error" as a general way to exit from pure code with
| a message.
|
| I'm not commenting about whether or not those are good practice, just
| reporting that they are out there.
|
| I would be in favor of this though if it is off by default and is
| turned on by an option or pragma. But not just -Werror, though, except
| for messages that would otherwise have been prefixed by "Warning",
| like the current behavior.
|
| Thanks,
| Yitz
|
|
|
| On Fri, Jan 23, 2015 at 1:04 PM, Konstantine Rybnikov