Re: Help wanted with bkgd() rookie mistake

[G. Branden Robinson]

At 2025-01-05T14:08:43-0500, Thomas Dickey wrote:
> > $ make
> > cc -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=600 bkgd.c -o bkgd -lncurses -ltinfo
> > cc -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=600 
> > -I/home/branden/ncurses-HEAD/include/ncursesw 
> > -I/home/branden/ncurses-HEAD/include bkgrnd.c -o bkgrnd 
> > -L/home/branden/ncurses-HEAD/lib -lncursesw -ltinfow -ldb
> 
> The -L option isn't doing much, because the system is picking the
> library.

Yes--I forgot, if I ever knew, that my ncurses builds don't create an
"ncurses6-config" program...just "ncurses6w-config".  The former is
found in /usr/bin, and the latter both in /usr/bin and
$HOME/ncurses-HEAD/bin, with the latter winning because $PATH.

So when I test "narrow" ncurses, I've only ever been testing Debian's
ncurses5 packages.  Oh great.  Well, I know now.

> That last LD_LIBRARY_PATH shows a different library.  It'll satisfy
> ldd either way, but the program linked (compile-time/link) against the
> libncurses.so.5 won't behave as expected because the offsets to the
> video-attribute changed between ABI 5 and 6.

I wonder if that's why neomutt cores.

It doesn't explain why bkgd() has a problem, but it could well be a 4+
year old bug that you fixed ages ago, and which happens to linger in
Debian's oldstable release.  I don't think an ABI mismatch explains
_this_ bug because I've been building my "narrow" test programs, as it
turns out, only against Debian's old libraries, and mostly I test
API-level stuff that hasn't changed in decades.

> (you could force it to ignore the default library path using the rpath
> feature, but that's a nuisance for one-offs).

I've never had to mess with rpath and I'm not anxious to start.

I'm thinking what I probably want to do is use the same compiler flags
for all of my test scripts, and distinguish them only by the API they
elect to use.  It's not like libncursesw.so.6 is missing the narrow
entry points.

Regards,
Branden

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