https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100734
--- Comment #5 from John David Anglin <danglin at gcc dot gnu.org> --- Breakpoint 1, attr_access::from_mode_char ( c=<error reading variable: Cannot access memory at address 0x0>) at ../../gcc/gcc/attribs.h:304 304 gcc_unreachable (); (gdb) bt #0 attr_access::from_mode_char ( c=<error reading variable: Cannot access memory at address 0x0>) at ../../gcc/gcc/attribs.h:304 #1 0x4000000000a8311c in init_attr_rdwr_indices (rwm=0x800003fffdff14e0, attrs=0x800003fffdf1b9b0) at ../../gcc/gcc/attribs.c:2146 #2 0x4000000000d1e554 in warn_parm_array_mismatch (origloc=2147484671, fndecl=0x800003fffdf1b9b0, newparms=0x7ae4b8) at ../../gcc/gcc/c-family/c-warn.c:3369 #3 0x4000000000b5ebc0 in c_parser_declaration_or_fndef ( parser=0x800003fffdff14e0, fndef_ok=128, static_assert_ok=false, empty_ok=true, nested=false, start_attr_ok=false, objc_foreach_object_declaration=0x4000000000887f48 <copy_list(tree_node*)::__FUNCTION__>, omp_declare_simd_clauses=..., have_attrs=false, attrs=0x800003fffdf1d700, oacc_routine_data=0x4000000002f7501f <fndecl_built_in_p(tree_node const*)+92>, fallthru_attr_p=0x800003fffdff17a0) at ../../gcc/gcc/c/c-parser.c:2342 #4 0x4000000000b5cb98 in c_parser_external_declaration ( parser=0x800003fffdff14e0) at ../../gcc/gcc/c/c-parser.c:1777 #5 0x4000000000b5c240 in c_parser_translation_unit (parser=0x800003fffdff14e0) at ../../gcc/gcc/c/c-parser.c:1650 #6 0x4000000000bc644c in c_parse_file () at ../../gcc/gcc/c/c-parser.c:21994 #7 0x4000000000cafd10 in c_common_parse_file () at ../../gcc/gcc/c-family/c-opts.c:1219 #8 0x40000000017db87c in compile_file () at ../../gcc/gcc/toplev.c:457 #9 0x40000000017e26e8 in do_compile () at ../../gcc/gcc/toplev.c:2203 #10 0x40000000017e2e68 in toplev::main (this=0x800003fffdff14e0, argc=-2147482625, argv=0x7ae4b8) at ../../gcc/gcc/toplev.c:2342 #11 0x4000000002abbee4 in main (argc=-2147482625, argv=0x800003fffdf1b9b0) at ../../gcc/gcc/main.c:39 (gdb) frame 1 #1 0x4000000000a8311c in init_attr_rdwr_indices (rwm=0x800003fffdff14e0, attrs=0x800003fffdf1b9b0) at ../../gcc/gcc/attribs.c:2146 2146 acc.mode = acc.from_mode_char (*m); (gdb) p *m $2 = 0 '\000'