Re: C, automake, testing change for compiling old c program

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

songbird's autotools wrote:
> configure: WARNING: sys/ioctl.h: see the Autoconf documentation
> configure: WARNING: sys/ioctl.h:     section "Present But Cannot Be

According to
  https://www.gnu.org/software/autoconf/manual/autoconf-2.64/html_node/Present-But-Cannot-Be-Compiled.html
you will have to find out where your auto-empire (starting at your
configure.ac) has a test which matches this grep expression:

  AC_CHECK_HEADER[S]*(.*sys/ioctl.h.*

and either fix it by giving the necessary helper headers or by just
throwing it out.

The helper headers would have to be determined by try and error and
then included in the fourth argument code snippet like "number.h" in
the autoconf documentation example.

Throwing out the test might suppress early failure on systems which have
no sys/ioctl.h or might prevent workarounds if it is missing. This depends
much on the second and third argument of the macro: [action-if-found],
[action-if-not-found].
See also
  https://www.gnu.org/software/autoconf/manual/autoconf-2.64/html_node/Generic-Headers.html#Generic-Headers
A quick look into my own code shows that i happily include <sys/ioctl.h>
but never check for its existence. Works on all contemporary Unixes and
with Cygwin.


Have a nice day :)

Thomas