Re: [Qemu-devel] [PATCH] configure: Define NCURSES_WIDECHAR if we're using curses

[Laszlo Ersek <lersek@redhat.com>]

On 06/02/17 16:35, Peter Maydell wrote:
> We want the wide character functions from the ncurses header.
> Unfortunately it doesn't provide them by default, but only
> if either:
>  * NCURSES_WIDECHAR is defined (for ncurses 20111030 and up)
>  * _XOPEN_SOURCE/_XOPEN_SOURCE_EXTENDED are suitably defined
> 
> So far we have been implicitly relying on the latter, because
> for GNU libc when we define _GNU_SOURCE this causes libc
> to define the _XOPEN_SOURCE macros for us. Unfortunately
> this doesn't work on all libcs, because some (like OSX and
> musl libc) do not define _XOPEN_SOURCE when _GNU_SOURCE
> is defined.
> 
> We can't fix this by defining _XOPEN_SOURCE ourselves, because
> that also means "and don't provide any functions that aren't in
> that standard", and not all libcs provide any way to override
> that to also get the non-standard functions. In particular
> FreeBSD has no such mechanism, and OSX's _DARWIN_C_SOURCE
> doesn't reenable everything (for instance getpagesize()
> is still not prototyped if _DARWIN_C_SOURCE and _XOPEN_SOURCE
> are both defined).
> 
> So we have to define NCURSES_WIDECHAR. (This will only work
> if your ncurses is at least 20111030, as older versions
> don't honour this macro.)
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Testing from the people with musl libc and OSX-with-ncurses
> appreciated, as I don't have any systems which have the bug
> which this patch is attempting to fix...
> 
>  configure | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/configure b/configure
> index 0586ec9..6aca5d1 100755
> --- a/configure
> +++ b/configure
> @@ -3053,6 +3053,8 @@ int main(void) {
>  EOF
>    IFS=:
>    for curses_inc in $curses_inc_list; do
> +    # Make sure we get the wide character prototypes
> +    curses_inc="-DNCURSES_WIDECHAR $curses_inc"
>      IFS=:
>      for curses_lib in $curses_lib_list; do
>        unset IFS
> 

Given that we're already consciously using non-portable functions, this
solution looks the least messy to me.

Acked-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo