https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115907
--- Comment #42 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to frankhb1989 from comment #41) > I ran into exact the same trouble of C23 missing symbols on old systems. In > my case it is a custom build (with tailored source) of libfreeimage which > has some calls to `sscanf` pulling the unwanted symbol references (to > `__isoc23_sscanf@GLIBC_2.38`) into the library That is not a glibc issue but rather you are thinking glibc will be forwards compatible; glibc is not and never can be; this is true for almost all OS out there (Mac OS has a similar issue though they provide sysroots with all needed headers/libraries so it is slightly easier to handle rather than you need to go out and find one). It is definitely backwards compatiable. If you want to build a program that runs on older systems you 100% need to use the earliest version of glibc to link (and use headers from) against rather than the newest version.
