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

[Paul Eggert]

On 6/20/19 10:46 PM, Eli Zaretskii wrote:
> > Every important Emacs stderr message ends in newline
> So now we will have to enforce this all over the place

It's already enforced, in the sense that (a) it's standard practice 
anyway, (b) a stderr diagnostic without a trailing newline is a bug 
since it'll mess up formatting for the next stderr diagnostic, and (c) 
POSIX allows platforms to line-buffer stderr by default and Emacs has 
been working on such platforms for ages anyway.

If it helps, I can audit all uses of stderr in the Emacs source to see 
if any newlines are being omitted. Any such omissions are buggy anyway 
for reasons (a), (b), and (c), and this is true regardless of whether 
Emacs explicitly enables line-buffering for stderr. I would not be 
surprised to find one or two bugs in the hundreds of diagnostics that 
Emacs generates, but now is as good a time as any to fix any bugs that I 
find.


> people don't expect stderr to be buffered
Actually I expected stderr to be line-buffered, a behavior that POSIX 
allows and that I vaguely recall when running GNU code (sorry, don't 
remember what platforms). Evidently things are different in the milieu 
of MS-Windows as it does not support line-buffering; still, Emacs and 
other GNU programs have worked with line-buffered stderr for ages.