bug#12911: 24.3.50; let users decide where (& perhaps whether) `emacs_backtrace.txt' files are written

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Making it in ~/.emacs.d on w32 alone doesn't change the basic fact
> that most of the users we care about will still have their backtraces
> in random places.

No, ~/.xsesson-errors is not a random place.  Even if the user doesn't
know it, we do.

> Why not change that on all platforms?

Because stderr is good enough under GNU/Linux (and it's easy to
redirect when it matters).

> Why demand that only of w32?

Because currently w32 users get annoyed with new files appearing where
they don't want any.  If you prefer to always send it to stderr under
Windows, please do so, I really couldn't care less if that means it's
usually sent to /dev/null.

> No, we disagree about the importance of uniformity in operation across
> platforms.

I suggested above another way to be uniform across platforms.

> Either the data is in a platform-specific place, in which
> case the current arrangement is as good as any,

No, writing to an arbitrary file in the current directory is not
a good arrangement.
I personally don't care whether it's uniform across platforms or not.

I didn't like the backtrace business to start with and am finding it
worse by the day.  And it doesn't even give me the info that the old
"assert in a macro" gave me.


        Stefan