sci-mathematics/giac: pari 2.15 compat + -gui workaround

Closes: https://github.com/gentoo/gentoo/pull/27625
Closes: https://bugs.gentoo.org/875179
Signed-off-by: François Bissey <frp.bissey@gmail.com>
Signed-off-by: Michael Orlitzky <mjo@gentoo.org>

sci-mathematics/giac/files/giac-1.9.0.21-pari-2.15.patch

@@ -0,0 +1,17 @@
+--- a/src/pari.cc
++++ b/src/pari.cc
+@@ -39,6 +39,14 @@ using namespace std;
+ #endif
+ 
+ #ifdef HAVE_LIBPARI
++#if !defined ANYARG
++// Anyarg disappeared from PARI 2.15.0
++#ifdef __cplusplus
++#  define ANYARG ...
++#else
++#  define ANYARG
++#endif
++#endif
+ 
+ #ifdef HAVE_PTHREAD_H
+ #include <pthread.h>

sci-mathematics/giac/giac-1.9.0.21.ebuild

@@ -49,6 +49,7 @@ BDEPEND="dev-tex/hevea
 PATCHES=(
 	"${FILESDIR}/${PN}-1.7.0.1-gsl_lapack.patch"
 	"${FILESDIR}/${PN}-1.6.0-pari-2.11.patch"
+	"${FILESDIR}/${PN}-1.9.0.21-pari-2.15.patch"
 )
 
 REQUIRED_USE="test? ( gui )"
@@ -74,6 +75,11 @@ src_configure() {
 
 		# Get the big-L flags from fltk's LDFLAGS.
 		append-ldflags $(fltk-config --ldflags | sed -e 's/\(-L\S*\)\s.*/\1/')
+	else
+		# see https://trac.sagemath.org/ticket/31563#comment:91 onwards.
+		# Unless this variable is defined a non existent function will be requested.
+		# The spelling is correct - upstream is French.
+		append-cppflags -DUSE_OBJET_BIDON=1
 	fi
 
 	# Using libsamplerate is currently broken