On 1/1/21 10:47 PM, Eli Zaretskii wrote:
> On the emacs-27
> branch, please just countermand the problematic condition with
> AIX-specific condition, as I don't want to change the configure script
> there.

I doubt whether the problem occurs only on AIX. As I understand it now, 
the problem can happen on any platform that uses the curses library from 
BSD via SVR4 and X/Open.

I now see that I misspoke when I wrote that Emacs uses libncurses on 
AIX. Emacs uses libcurses, because XLC-generated executables cannot link 
to libncurses, as libncurses requires libgcc_s.a which is a GCC-ism.

I don't offhand see how to fix this with a condition in the C code, so 
on the emacs-27 branch I merely documented the issue via the attached patch.

My guess is that the issue is rare, as the original curses library has 
been obsolete for quite some time. And given that curses does not work 
in Emacs 27 and this is the first bug report about it and I found it 
only by doing some extensive portability checking, perhaps we should 
instead drop support for curses, and insist on ncurses or tinfo or 
terminfo. I wouldn't be surprised if the Emacs curses code has other 
issues that we don't know about because nobody uses it.