Re: `message' not outputting the newline "atomically"

[Paul Eggert]

On 6/20/19 5:52 AM, Eli Zaretskii wrote:
> stderr is unbuffered for a reason,

No: POSIX allows stderr to be line-buffered, or to use any other kind of 
buffering that is not fully buffered, and many platforms do just that 
instead of having stderr be unbuffered (which is quite inefficient on 
some platforms). It's true that stderr is unbuffered on MS-Windows, but 
the change does not affect MS-Windows behavior so there should be no 
problem there.

All this change is doing (on non-MS-Windows platforms) is to use line 
buffering on stderr, which is fine for Emacs as it's what Emacs does 
already on some platforms.