Fix some Clang warnings I saw in Clang 22

[evantypanski]

Claude did all of this, I checked to make sure it makes sense. Does to me, at least. These are all minor so I am not going to make a fuss about them.

Looks unresponsive upstream so I'll only open here unless some signs of life show up.

Here are the warnings for the curious:

output

$ ninja [3/13] Building C object CMakeFiles/fiber.dir/src/fiber.c.o In file included from /Users/etyp/src/fiber/src/fiber.c:1: In file included from /Users/etyp/src/fiber/include/fiber/fiber.h:27: /Users/etyp/src/fiber/include/fiber/fiber_mach.h:134:20: warning: extra ';' inside a struct [-Wextra-semi] 134 | FIBER_ARCH_REGS; | ^ /Users/etyp/src/fiber/src/fiber.c:71:6: warning: cast from 'char *' to 'void **' increases required alignment from 1 to 8 [-Wcast-align] 71 | *(void **) *sp = val; | ^~~~~~~~~~~~~ /Users/etyp/src/fiber/src/fiber.c:89:15: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement] 89 | uintptr_t sp = | ^ /Users/etyp/src/fiber/src/fiber.c:150:14: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes] 150 | get_page_size() | ^ | void /Users/etyp/src/fiber/src/fiber.c:195:18: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement] 195 | const size_t stack_size = size; | ^ /Users/etyp/src/fiber/src/fiber.c:288:1: warning: identifier '_probe_stack_weak_dummy' is reserved because it starts with '_' at global scope [-Wreserved-identifier] 288 | _probe_stack_weak_dummy(volatile char *sp, size_t sz); | ^ /Users/etyp/src/fiber/src/fiber.c:308:10: warning: cast from 'volatile char *' to 'volatile uintptr_t *' (aka 'volatile unsigned long *') increases required alignment from 1 to 8 [-Wcast-align] 308 | *(volatile uintptr_t *) sp |= (uintptr_t) 0; | ^~~~~~~~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/src/fiber.c:306:12: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement] 306 | size_t i = 0; | ^ /Users/etyp/src/fiber/src/fiber.c:327:16: warning: implicit conversion when initializing 'char *' with an expression of type 'void *' is not permitted in C++ [-Wimplicit-void-ptr-cast] 327 | char *sp = hu_cxx_static_cast(char *, fbr->regs.sp); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/deps/cxx-header-utils/include/hu/lang.h:62:42: note: expanded from macro 'hu_cxx_static_cast' 62 | # define hu_cxx_static_cast(T, x) hu_c_implicit_cast(T, x) | ^~~~~~~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/deps/cxx-header-utils/include/hu/lang.h:57:17: note: expanded from macro 'hu_c_implicit_cast' 57 | hu_c_implicit_cast_(T, x, __COUNTER__) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/deps/cxx-header-utils/include/hu/lang.h:53:23: note: expanded from macro 'hu_c_implicit_cast_' 53 | T hu_c_implicit_cast_val##cnt = (x); \ | ^ ~~~ <scratch space>:452:1: note: expanded from here 452 | hu_c_implicit_cast_val__COUNTER__ | ^ /Users/etyp/src/fiber/src/fiber.c:337:12: warning: 'is_stack_aligned' was marked unused but was used [-Wused-but-marked-unused] 337 | assert(is_stack_aligned(sp)); | ^ /Users/etyp/src/fiber/src/fiber.c:344:12: warning: 'is_stack_aligned' was marked unused but was used [-Wused-but-marked-unused] 344 | assert(is_stack_aligned(sp)); | ^ /Users/etyp/src/fiber/src/fiber.c:327:11: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement] 327 | char *sp = hu_cxx_static_cast(char *, fbr->regs.sp); | ^ /Users/etyp/src/fiber/src/fiber.c:371:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes] 371 | fiber_stack_alignment() | ^ | void /Users/etyp/src/fiber/src/fiber.c:70:5: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 70 | *sp -= WORD_SIZE; | ^~~ /Users/etyp/src/fiber/src/fiber.c:90:40: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 90 | (uintptr_t) ((char *) fbr->stack + fbr->stack_size - WORD_SIZE); | ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/src/fiber.c:90:20: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 90 | (uintptr_t) ((char *) fbr->stack + fbr->stack_size - WORD_SIZE); | ^~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/src/fiber.c:218:19: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 218 | (char *) fbr->alloc_stack + (npages - 1) * pgsz, false))) | ^~~~~~~~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/deps/cxx-header-utils/include/hu/annotations.h:481:62: note: expanded from macro 'hu_unlikely' 481 | # define hu_unlikely(x) (__builtin_expect(HU_BOOL_CONTEXT(x), HU_BOOL_FALSE)) | ^ /Users/etyp/src/fiber/deps/cxx-header-utils/include/hu/annotations.h:21:32: note: expanded from macro 'HU_BOOL_CONTEXT' 21 | #define HU_BOOL_CONTEXT(p) (!!(p)) | ^ /Users/etyp/src/fiber/src/fiber.c:221:26: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 221 | fbr->stack = (char *) fbr->alloc_stack + pgsz; | ^~~~~~~~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/src/fiber.c:254:26: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 254 | protect_page((char *) fbr->alloc_stack + npages * pgsz, true); | ^~~~~~~~~~~~~~~~~~~~~~~~~ /Users/etyp/src/fiber/src/fiber.c:310:9: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 310 | sp -= pgsz; | ^~ /Users/etyp/src/fiber/src/fiber.c:330:24: warning: unsafe pointer arithmetic [-Wunsafe-buffer-usage] 330 | sp = stack_align_n(sp - args_size, arg_align); | ^~ 21 warnings generated.