Issue #20908 has been updated by nobu (Nobuyoshi Nakada). Can't we prioritize the condition `defined(rb_define_method)` for `RUBY_METHOD_FUNC`? ---------------------------------------- Bug #20908: Ruby extension builds fail with GCC 15 which defaults to -std=gnu23 https://bugs.ruby-lang.org/issues/20908#change-110750 * Author: thesamesam (Sam James) * Status: Third Party's Issue * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Hi! Upcoming GCC 15 defaults to C23 (`-std=gnu23`). One thing C23 changes is removing unprototyped functions, so `void foo()` now means `void foo(void)`, rather than "any arguments". Ruby extensions fail to build as a result with GCC 15. This was reported downstream in Gentoo at https://bugs.gentoo.org/943784 where brotli-0.6.0 is an example: ``` make: Entering directory '/var/tmp/portage/dev-ruby/brotli-0.6.0/work/ruby32/brotli-0.6.0/ext/brotli' x86_64-pc-linux-gnu-gcc -I. -I/usr/include/ruby-3.2.0/x86_64-linux -I/usr/include/ruby-3.2.0/ruby/backward -I/usr/include/ruby-3.2.0 -I. -DHAVE_BROTLI_DECODE_H -DHAVE_BROTLI_ENCODE_H -fPIC -O2 -pipe -march=native -fno-diagnostics-color -o brotli.o -c brotli.c In file included from /usr/include/ruby-3.2.0/ruby/ruby.h:27, from /usr/include/ruby-3.2.0/ruby.h:38, from brotli.h:4, from brotli.c:1: brotli.c: In function ‘Init_brotli’: /usr/include/ruby-3.2.0/ruby/internal/anyargs.h:363:45: error: passing argument 3 of ‘rb_define_singleton_method_m1’ from incompatible pointer type [-Wincompatible-pointer-types] 363 | # define RUBY_METHOD_FUNC(func) RBIMPL_CAST((VALUE (*)(ANYARGS))(func)) | ^ | | | VALUE (*)(void) {aka long unsigned int (*)(void)} /usr/include/ruby-3.2.0/ruby/internal/anyargs.h:308:144: note: in definition of macro ‘rb_define_singleton_method’ 308 | #define rb_define_singleton_method(obj, mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method((arity), (func))((obj), (mid), (func), (arity)) | ^~~~ /usr/include/ruby-3.2.0/ruby/internal/anyargs.h:363:33: note: in expansion of macro ‘RBIMPL_CAST’ 363 | # define RUBY_METHOD_FUNC(func) RBIMPL_CAST((VALUE (*)(ANYARGS))(func)) | ^~~~~~~~~~~ brotli.c:478:55: note: in expansion of macro ‘RUBY_METHOD_FUNC’ 478 | rb_define_singleton_method(rb_mBrotli, "deflate", RUBY_METHOD_FUNC(brotli_deflate), -1); | ^~~~~~~~~~~~~~~~ /usr/include/ruby-3.2.0/ruby/internal/anyargs.h:271:21: note: expected ‘VALUE (*)(int, union <anonymous>, VALUE)’ {aka ‘long unsigned int (*)(int, union <anonymous>, long unsigned int)’} but argument is of type ‘VALUE (*)(void)’ {aka ‘long unsigned int (*)(void)’} 271 | RBIMPL_ANYARGS_DECL(rb_define_singleton_method, VALUE, const char *) | ^~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/include/ruby-3.2.0/ruby/internal/anyargs.h:254:41: note: in definition of macro ‘RBIMPL_ANYARGS_DECL’ 254 | RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _m1(__VA_ARGS__, VALUE(*)(int, union { VALUE *x; const VALUE *y; } __attribute__((__transparent_union__)), VALUE), int); \ | ^~~ ``` The `ANYARGS` macro can't work in its current form, as defined at e.g. https://github.com/ruby/ruby/blob/f127bcb8294fd417c253dd7acab3ff3b9f0bf555/p...: ``` #ifndef ANYARGS # ifdef __cplusplus # define ANYARGS ... # else # define ANYARGS # endif #endif ``` ... because of the change in C23 I mentioned above, i.e. `(ANYARGS)` being `()` now means no arguments, not any. I note that Ruby was adapted in part already for this change, see e.g. https://github.com/ruby/ruby/commit/4e64edb6cd8d1b444c591bfd50ec3d357e794f6e, but it appears that the headers that extensions need to build against aren't yet ready. -- https://bugs.ruby-lang.org/