Project: modernc.org/libc (darwin) ## Environment - modernc.org/libc v1.75.7, darwin/arm64 and darwin/amd64, as pinned by the originating project. ## Origin This report records findings made by the third-party project github.com/Tryanks/cpython-go, a ccgo transpilation of CPython 3.14 (commit ab9a153, 2026-09-05). The project is not mine; I am filing the findings so they are not lost. Unless stated otherwise, the items below are taken from comments in that repository and were not independently verified. ## Findings 1. Functions absent from the darwin libc. The project seeds configure with these answers (generator.go, configureEnvOS["darwin"], comment: "functions modernc.org/libc lacks on a platform; CPython has fallbacks for all of them"): ac_cv_func_faccessat=no ac_cv_func_fchmodat=no ac_cv_func_fchownat=no ac_cv_func_fdopendir=no ac_cv_func_fstatat=no ac_cv_func_futimens=no ac_cv_func_getloadavg=no ac_cv_func_kqueue=no ac_cv_func_lchmod=no ac_cv_func_linkat=no ac_cv_func_mkdirat=no ac_cv_func_mkfifoat=no ac_cv_func_mknodat=no ac_cv_func_openat=no ac_cv_func_posix_spawn=no ac_cv_func_posix_spawnp=no ac_cv_func_readlinkat=no ac_cv_func_renameat=no ac_cv_func_sigaltstack=no ac_cv_func_symlinkat=no ac_cv_func_unlinkat=no ac_cv_func_utimensat=no ac_cv_func_waitid=no ac_cv_func_posix_openpt=no ac_cv_func_grantpt=no ac_cv_func_unlockpt=no ac_cv_func_ptsname=no ac_cv_func_ptsname_r=no ac_cv_func_pthread_getname_np=no ac_cv_func_pthread_setname_np=no ac_cv_func_getlogin_r=no 2. Functions present but routed to Go replacements. generator.go, comment on the rewrite: > libc functions whose darwin implementation is incomplete (panics with TODO for arguments CPython uses) are routed to libpython/libc_darwin.go. libpython/libc_darwin.go: > Routed here by generator.go (shimmedLibc) because the modernc.org/libc darwin versions panic with TODO for arguments CPython uses. The complete shimmedLibc["darwin"] list from generator.go (kept sorted by the project): __builtin___snprintf_chk __builtin___sprintf_chk __builtin___vsnprintf_chk __builtin_log2 __maskrune __srget __tolower __toupper accept alarm cfgetospeed chflags chown confstr dup2 endpwent fcntl fpathconf fprintf freeaddrinfo gai_strerror getaddrinfo getegid getgid getgrgid_r getgrnam_r getnameinfo getpwent getpwnam_r getpwuid_r getservbyname getsockopt inet_ntoa inet_ntop inet_pton kill link localeconv localtime localtime_r mbstowcs mknod mktime nanosleep nl_langinfo openpty pathconf poll pow printf pthread_key_delete pthread_sigmask raise read readv recv recvfrom recvmsg select send sendmsg sendto setenv setlocale setpwent setsockopt sigaction siginterrupt strerror strftime sysconf tcgetattr tcsetattr truncate ungetc unsetenv vfprintf write Not every entry is a TODO panic; the sockets group (accept, getaddrinfo, getnameinfo, inet_ntop, inet_pton, recvmsg, sendmsg, ...) also carries the project's IPv6 and ancillary-data support, the locale group (localeconv, nl_langinfo, setlocale, strftime) its locale emulation, and read/write/recv/send the signal interruptibility described in the Linux report filed alongside this one. 3. Wrong Go signatures. generator.go passes, for darwin only: // modernc.org/libc (darwin) declares these with the wrong Go signature; route them to our shims in libpython/libc_darwin.go. "-Dsched_yield=ccgo_sched_yield", "-Dwcschr=ccgo_wcschr", The project's replacements have the signatures func(tls *libc.TLS) int32 and func(tls *libc.TLS, s uintptr, c int32) uintptr. 4. link on darwin/amd64. libpython/libc_darwin.go: > Routed here by generator.go: modernc's darwin/amd64 Xlink is a TODO panic. 5. Additional undefined symbols the project supplies for darwin (undefined-symbol route, functions named _<symbol> in package libpython): _pthread_cond_timedwait_relative_np, _pthread_get_stackaddr_np, _pthread_get_stacksize_np, _clock_getres and others in libpython/libc_darwin.go and libpython/cstack.go. The Windows and Linux builds have their own such lists. 6. libm accuracy. TODO.md of the project: > test_math: Darwin's CPython `m_tgamma` path, using Go-backed math primitives, is 27-787 ulps beyond the test-file tolerances at six cases. Replacing it requires a C patch plus regeneration. Linux's same wrapper over transpiled musl primitives passes all 89 tests and must not be rerouted. pow and __builtin_log2 are among the darwin routed functions above; the project's replacement for log2 is in libpython/libc_darwin.go. 7. Compiler builtins routed on darwin: __builtin___snprintf_chk, __builtin___sprintf_chk, __builtin___vsnprintf_chk (the project formats these itself in libpython/printf.go, together with printf, fprintf and vfprintf). The report on missing builtins and 8/16-bit atomic helpers, filed alongside this one, lists the builtins missing on every platform.