Version 2.8 of GSL does not have a definition for the function gsl_bspline_eval_nonzero and this causes several libraries dependent on this function to fail to compile with recent GCC. For example:

LALSimulation, part of lalsuite fails on openSUSE Tumbleweed with:

  [   19s] LALSimIMRSEOBNRROMUtilities.c:455:3: error: implicit declaration of function 'gsl_bspline_eval_nonzero'; did you mean 'gsl_spline_eval_integ'? [-Werror=implicit-function-declaration]
  [   19s]   455 |   gsl_bspline_eval_nonzero(eta,  Bx4, &isx, &iex, bwx);

I understand that this function is slated for deprecation, but other functions with similar status in old.c still have definitions in gsl_bspline.h:

/* future to be deprecated functions */

size_t gsl_bspline_ncoeffs (gsl_bspline_workspace * w);
int gsl_bspline_knots (const gsl_vector * breakpts, gsl_bspline_workspace * w);
int gsl_bspline_knots_uniform (const double a, const double b, gsl_bspline_workspace * w);
int gsl_bspline_eval (const double x, gsl_vector * B, gsl_bspline_workspace * w);
int gsl_bspline_deriv_eval (const double x, const size_t nderiv,
                            gsl_matrix * dB, gsl_bspline_workspace * w);
int gsl_bspline_knots_greville (const gsl_vector *abscissae,
                                gsl_bspline_workspace *w,
                                double *abserr);

/* end of future to be deprecated functions */