signbit issues

[Orion Poplawski]

I'm trying to track down a possible issue with gnulib signbit and gcc 6 as
reported here:

https://savannah.gnu.org/bugs/index.php?47073

In file included from /usr/include/suitesparse/cs.h:5:0,
from ./util/oct-sparse.h:77,
from array/CSparse.cc:55:
../libgnu/math.h: In function 'int signbit(float)':
../libgnu/math.h:2576:1: error: 'int signbit(float)' conflicts with a previous
declaration
_GL_MATH_CXX_REAL_FLOATING_DECL_2 (signbit)
^
In file included from /usr/include/c++/6.0.0/complex:44:0,
from ./util/oct-cmplx.h:27,
from numeric/lo-mappers.h:29,
from array/CSparse.cc:36:
/usr/include/c++/6.0.0/cmath:681:3: note: previous declaration 'constexpr bool
std::signbit(float)'
signbit(float __x)
^~~~~~~

So first I tried setting up a simple project with gnulib an signbit:

../gnulib/gnulib-tool --import signbit

but I'm getting:

$ autoreconf -f
lib/Makefile.am:66: error: GL_GENERATE_FLOAT_H does not appear in AM_CONDITIONAL
autoreconf: automake failed with exit status: 1

m4/float_h.m4 seems to have this:

./m4/float_h.m4:  AM_CONDITIONAL([GL_GENERATE_FLOAT_H], [test -n "$FLOAT_H"])

but this isn't getting included perhaps?

$ grep -F m4_include aclocal.m4
m4_include([m4/fpieee.m4])
m4_include([m4/gnulib-common.m4])
m4_include([m4/gnulib-comp.m4])

I'm afraid I'm not very experience with automake/autoconf so perhaps I've
messed something else up.

$ cat configure.ac
AC_INIT(test, 1.0, address@hidden)
AC_CONFIG_SRCDIR(src/foobar.cpp)
AM_INIT_AUTOMAKE
AC_PROG_CC
gl_EARLY
AC_PROG_CXX
AC_PROG_RANLIB
AC_CONFIG_FILES(lib/Makefile)
AC_OUTPUT(Makefile src/Makefile)
gl_iNIT


$ cat Makefile.am
ACLOCAL_AMFLAGS = -I m4
SUBDIRS = lib src
EXTRA_DIST = m4/gnulib-cache.m4 autogen.sh


Any help would be greatly appreciated.

-- 
Orion Poplawski
Technical Manager                     303-415-9701 x222
NWRA, Boulder/CoRA Office             FAX: 303-415-9702
3380 Mitchell Lane                       address@hidden
Boulder, CO 80301                   http://www.nwra.com