Agile Developer wrote: > I was wondering whether GNU objective-c, as implemented on top of C, > supports C23 and if the objective-c implementation is interoperable > with C23.
The default C standard when compiling Objective-C code with GCC is C89 so as Ethan said, you must specify -std=c23 or -std=gnu23. Note that there are some subtle bugs like these: GCC rejects a "for" loop declaration for a variable named "in" as this is reserved for fast enumeration (which works in C89 for Objective-C only): https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46473 GCC fails to recognize an ivar in a method implementation, confusing it with an "if" variable declaration: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119117
