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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"configure: the musl guard for PR_SET_VMA_ANON_NAME tests an unset variable","articleBody":"gh-143730 disabled the `PR_SET_VMA_ANON_NAME` check on musl, but the guard tests a variable\nthat is never set:\n\n```\nconfigure.ac:6009:AS_IF([test \"$ac_cv_libc\" != musl], [\n```\n\n`ac_cv_libc` appears nowhere else, so the check always runs.\n\nOn x86_64 musl this goes unnoticed, because the conftest fails to compile anyway and the macro\nstays undefined. On i686 musl it compiles, `_Py_HAVE_PR_SET_VMA_ANON_NAME` gets defined, and the\nbuild then fails on the conflict the guard was meant to avoid:\n\n```\nIn file included from ../Include/internal/pycore_mmap.h:16, from ../Objects/obmalloc.c:5:\n/usr/include/sys/prctl.h:88:8: error: redefinition of 'struct prctl_mm_map'\n/usr/include/linux/prctl.h:134:8: note: originally defined here\n```\n\nWorkaround: `./configure ac_cv_have_decl_PR_SET_VMA_ANON_NAME=no`.\n\n3.14 is unaffected (no `pycore_mmap.h`).\n\n\n\u003c!-- gh-linked-prs -->\n### Linked PRs\n* gh-159886\n\u003c!-- /gh-linked-prs -->\n","author":{"url":"https://github.com/serhiy-storchaka","@type":"Person","name":"serhiy-storchaka"},"datePublished":"2026-10-20T14:20:19Z","url":"https://github.com/python/cpython/issues/159885"}