Qhull and scripts/geometry

[Petr Mikulik]

> >> | Yes; configuring Qhull with
> >> |     CFLAGS="-fno-strict-aliasing -O2" ./configure $*
> >> | does not crash the testing command
> >> |      rbox c D3 | qconvex s G
> >> |
> >> | Could Octave's ./configure test the Qhull library? I propose that if the
> >> | above test command (or some C++ source test case) crashes, then Octave does
> >> | not link to Qhull library and writes a hint like
> >> |   Crashing Qhull found; please recompile the Qhull library by
> >> |     CFLAGS="-fno-strict-aliasing -O2" ./configure; make
> >>
> >> Can you provide an autoconf macro that does the test and does not
> >> require an external program?  My Debian sysstem has the library but
> >> the test programs are not installed.
> >>
> >> There is also the issue that running test programs limits the
> >> usefulness of configure scripts when cross-compiling.  In this case, I
> >> guess we would just have to assume that the library works when cross
> >> compiling.
> >
> > I've prepared the shortest code that leads to crash if the Qhull library has
> > been compiled without the appropriate CFLAGS.
> >
> > Usage:
> >    gcc -o QhullCrashTest QhullCrashTest.c -lqhull -lm
> >    echo "2 4 -0.5 -0.5 -0.5 0.5 0.5 -0.5 0.5 0.5" | ./QhullCrashTest
> >
> > If it crashes, nothing is written on stdout.
> > If it does not crash, an "OK message" is written on stdout.
> >
> > Could this testing program be used in the Octave configure?
> > I don't know how to write an autoconf macro for it.
> >
> 
> Hi Petr,
> 
> I'll take care of the inclusion into configure. However, for best
> suitability for autoconf macros (AC_RUN_IFELSE), please modify the
> test program in the following manner:
> 1. make the inputs part of the source
> 2. indicate success by returning exit code zero. If you can do it, to
> make the test more complete, I suggest also to check the results for
> correctness (if a crash doesn't happen on some system, but instead
> incorrect results are produced).

I have no idea how to put the input data into the testing program.

The success is indicated by zero exit code ("return 0"); failure is 
indicated by crash with a "Segmentation fault" ... the return value seems to 
be 139.

---
Petr Mikulik