https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61831
--- Comment #16 from Dominique d'Humieres <dominiq at lps dot ens.fr> --- >From the files in the attachment in comment 8, the files that are affected by this PR are beams.f90, models.f90, and process_libraries.f90: beams.f90: In function 'beam_data_write': beams.f90:144:0: internal compiler error: in gfc_conv_expr_reference, at fortran/trans-expr.c:6519 prt_name_len = maxval (len (flavor_get_name (beam_data%flv))) models.f90:1418:0: internal compiler error: in gfc_conv_expr_reference, at fortran/trans-expr.c:6519 maxval (len (particle_data_get_name (model%prt, .true.)))) process_libraries.f90: In function 'process_libraries_8': process_libraries.f90:2429:0: internal compiler error: in gfc_conv_expr_reference, at fortran/trans-expr.c:6519 variant = core_def) (using a version giving an ICE when using the faulty code). One thing you can try is to make WHIZARD with 4.9.1, then compile the above files with 4.9.0, make again, and see if the problem goes away.