René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Python 3.11 is unbuildable with GCC on macOS (error: 'HAVE_MKFIFOAT_RUNTIME' undeclared, error: 'HAVE_MKNODAT_RUNTIME' undeclared)","articleBody":"\u003c!--\r\n  If you're new to Python and you're not sure whether what you're experiencing is a bug, the CPython issue tracker is not\r\n  the right place to seek help. Consider the following options instead:\r\n\r\n  - reading the Python tutorial: https://docs.python.org/3/tutorial/\r\n  - posting in the \"Users\" category on discuss.python.org: https://discuss.python.org/c/users/7\r\n  - emailing the Python-list mailing list: https://mail.python.org/mailman/listinfo/python-list\r\n  - searching our issue tracker (https://github.com/python/cpython/issues) to see if\r\n    your problem has already been reported\r\n--\u003e\r\n\r\n# Bug report\r\n\r\nDue to missing fallback macro definitions in `Modules/posixmodule.c` ([source](\r\nhttps://github.com/python/cpython/blob/main/Modules/posixmodule.c#LL87C1-L108C31)) for `HAVE_MKFIFOAT_RUNTIME` and `HAVE_MKNODAT_RUNTIME`, Python 3.11 cannot be built with GCC on macOS, due to the following failures:\r\n\r\n```\r\n./Modules/posixmodule.c: In function 'parse_posix_spawn_flags':\r\n./Modules/posixmodule.c:186:64: warning: comparison between pointer and integer\r\n  186 |                                 (posix_spawn != NULL \u0026\u0026 setsid != NULL)\r\n      |                                                                ^~\r\n./Modules/posixmodule.c:6026:13: note: in expansion of macro 'HAVE_POSIX_SPAWN_SETSID_RUNTIME'\r\n 6026 |         if (HAVE_POSIX_SPAWN_SETSID_RUNTIME) {\r\n      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r\n./Modules/posixmodule.c: In function 'os_mkfifo_impl':\r\n./Modules/posixmodule.c:10690:17: error: 'HAVE_MKFIFOAT_RUNTIME' undeclared (first use in this function); did you mean 'HAVE_MKDIRAT_RUNTIME'?\r\n10690 |             if (HAVE_MKFIFOAT_RUNTIME) {\r\n      |                 ^~~~~~~~~~~~~~~~~~~~~\r\n      |                 HAVE_MKDIRAT_RUNTIME\r\n./Modules/posixmodule.c:10690:17: note: each undeclared identifier is reported only once for each function it appears in\r\n./Modules/posixmodule.c: In function 'os_mknod_impl':\r\n./Modules/posixmodule.c:10759:17: error: 'HAVE_MKNODAT_RUNTIME' undeclared (first use in this function); did you mean 'HAVE_MKDIRAT_RUNTIME'?\r\n10759 |             if (HAVE_MKNODAT_RUNTIME) {\r\n      |                 ^~~~~~~~~~~~~~~~~~~~\r\n      |                 HAVE_MKDIRAT_RUNTIME\r\n./Modules/posixmodule.c: In function 'probe_mkfifoat':\r\narm64-apple-darwin22-gcc  -Wsign-compare -DNDEBUG     -O2 -pipe -fwrapv -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal  -I. -I./Include -I/Users/gentoo/gentoo/tmp/usr/include/ncursesw   -DPy_BUILD_CORE_BUILTIN -c ./Modules/_codecsmodule.c -o Modules/_codecsmodule.o\r\n./Modules/posixmodule.c:15647:23: error: 'HAVE_MKFIFOAT_RUNTIME' undeclared (first use in this function); did you mean 'HAVE_MKDIRAT_RUNTIME'?\r\n15647 | PROBE(probe_mkfifoat, HAVE_MKFIFOAT_RUNTIME)\r\n      |                       ^~~~~~~~~~~~~~~~~~~~~\r\n./Modules/posixmodule.c:15611:11: note: in definition of macro 'PROBE'\r\n15611 |       if (test) {        \\\r\n      |           ^~~~\r\n./Modules/posixmodule.c: In function 'probe_mknodat':\r\n./Modules/posixmodule.c:15651:22: error: 'HAVE_MKNODAT_RUNTIME' undeclared (first use in this function); did you mean 'HAVE_MKDIRAT_RUNTIME'?\r\n15651 | PROBE(probe_mknodat, HAVE_MKNODAT_RUNTIME)\r\n      |                      ^~~~~~~~~~~~~~~~~~~~\r\n./Modules/posixmodule.c:15611:11: note: in definition of macro 'PROBE'\r\n15611 |       if (test) {        \\\r\n      |           ^~~~\r\nmake: *** [Makefile:2695: Modules/posixmodule.o] Error 1\r\nmake: *** Waiting for unfinished jobs....\r\n```\r\n\r\nIn `Modules/posixmodule.c`, Python conditionally defines a series of macros that indicate whether a system call is supported based on `#ifdef` checks. By default, the clang specific `__builtin_available()` compiler built-in function is used to check them. But if `__builtin_available()` is unavailable, a fallback is also provided.\r\n\r\nFor example, for `HAVE_FSTATAT_RUNTIME`, we have:\r\n\r\n```\r\n#ifdef HAVE_BUILTIN_AVAILABLE\r\n#  define HAVE_FSTATAT_RUNTIME __builtin_available(macOS 10.10, iOS 8.0, *)\r\n// [...]\r\n\r\n#else /* Xcode 8 or earlier */\r\n\r\n   /* __builtin_available is not present in these compilers, but\r\n    * some of the symbols might be weak linked (10.10 SDK or later\r\n    * deploying on 10.9.\r\n    *\r\n    * Fall back to the older style of availability checking for\r\n    * symbols introduced in macOS 10.10.\r\n    */\r\n\r\n#  ifdef HAVE_FSTATAT\r\n#    define HAVE_FSTATAT_RUNTIME (fstatat != NULL)\r\n#  endif\r\n\r\n#endif\r\n\r\n```\r\n\r\nThe fallback is important because it's not only used to support older Xcode or macOS, but it also provides fallback when GCC is used. The function `__builtin_available()` is clang-only and does not exist in GCC. In the past, this was handled by the `else` portion of the `ifdef`, so it worked on GCC as well. Unfortunately,  when `HAVE_MKFIFOAT_RUNTIME` and `HAVE_MKDIRAT_RUNTIME` have been added to the code, a fallback was never provided, thus, compiling Python 3.11 with GCC now fails due to undeclared macros.\r\n\r\n# Your environment\r\n\r\n\u003c!-- Include as many relevant details as possible about the environment you experienced the bug in --\u003e\r\n\r\n- CPython versions tested on: Python 3.11.3\r\n- Operating system and architecture: macOS 13.2.1\r\n- GCC 12.2.0\r\n\r\n\u003c!--\r\nYou can freely edit this text. Remove any lines you believe are unnecessary.\r\n--\u003e\r\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-104129\n* gh-104187\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/biergaizi","@type":"Person","name":"biergaizi"},"datePublished":"2023-05-02T21:38:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/104106/cpython/issues/104106"}