Re: <ncursesw/curses.h> and addnwstr

[Florian Weimer]

* Thomas Dickey:

> On Fri, Mar 17, 2023 at 07:15:26PM +0100, Florian Weimer wrote:
>> ocaml-curses has a configure check like this
>> 
>>     AC_MSG_CHECKING(for wide character support in ncurses library)
>>     AC_TRY_LINK(
>>       [#include <wchar.h>
>>        #include CURSES_HEADER
>>       ],
>>       [wchar_t wch = 0;
>          ^^^^^^ this is declared via wchar.h, but the wide-character curses.h
>               would include that, making the #include redundant.

In theory, the header could use a private type like __wchar_t, I guess.

>>        addnwstr(&wch, 1);],
>>       [AC_MSG_RESULT(yes)
>>        AC_DEFINE(HAVE_WIDE_CURSES, 1, [Defined if ncurses library includes 
>> wide character support])
>>        BOOL_WIDE_CURSES="true"],
>>       [AC_MSG_RESULT(no)])
>> 
>> CURSES_HEADER in our builds is <ncursesw/curses.h>.  But curiously, that
>> does not declare define, only <curses.h> does.  The symbol is defined in
>                    ^^ not sure what you're indicating here

I meant to write addnwstr.

> But the wide-character features also (even for X/Open Curses) have
> to have a symbol defined to declare them.  There's a section in
> the ncurses manpage mentioning that:
>
>             •   Alternatively,   you   can  enable  the  feature  by  defining
>                 NCURSES_WIDECHAR with the caveat that some other  header  file
>                 than  curses.h  may require a specific value for _XOPEN_SOURCE
>                 (or a system-specific symbol).
>
> (actually, NetBSD doesn't require a symbol, but that's in the 60% which
> it hasn't implemented yet :-)

Ahh, so I changed it to this:

    AC_TRY_LINK(
      [#include <wchar.h>
       #define NCURSES_WIDECHAR 1
       #include CURSES_HEADER
      ],
      [wchar_t wch = 0;
       addnwstr (&wch)],
      [AC_MSG_RESULT(yes)
       AC_DEFINE(HAVE_WIDE_CURSES, 1, [Defined if ncurses library includes wide 
character support])
       BOOL_WIDE_CURSES="true"],
      [AC_MSG_RESULT(no)])

Just addding “#define NCURSES_WIDECHAR 1” (the 1 is significant).  That
seems to work—I now get a declaration of addnwstr.

Thanks,
Florian