[libcxx-commits] [libcxx] [libcxx][FreeBSD] Mark unsupported only in _XOPEN_SOURCE=500 (PR #216002)

[via libcxx-commits]

https://github.com/aokblast updated https://github.com/llvm/llvm-project/pull/216002

>From 0d42d9aecff5aba3e18aeaa0e248c796255df156 Mon Sep 17 00:00:00 2001
From: ShengYi Hung <aokblast at FreeBSD.org>
Date: Thu, 13 Aug 2026 22:17:54 +0800
Subject: [PATCH] [libcxx][FreeBSD] Add comments for unsupported
 xopen_source.gen.py test

FreeBSD _XOPEN_SOURCE doesn't fullfill some requirements in libcxx. As a
result, it breaks test since trying to find the declaration of
functions.
---
 libcxx/test/extensions/posix/xopen_source.gen.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libcxx/test/extensions/posix/xopen_source.gen.py b/libcxx/test/extensions/posix/xopen_source.gen.py
index 99e0b0b7c7d1f..ac04e38bde38a 100644
--- a/libcxx/test/extensions/posix/xopen_source.gen.py
+++ b/libcxx/test/extensions/posix/xopen_source.gen.py
@@ -16,8 +16,10 @@
 # recent value of _XOPEN_SOURCE.
 # UNSUPPORTED: LIBCXX-AIX-FIXME
 
-# This test fails on FreeBSD for an unknown reason.
-# UNSUPPORTED: LIBCXX-FREEBSD-FIXME
+# FreeBSD maps _XOPEN_SOURCE=500 to __ISO_C_VISIBLE=1990 (see <sys/_visible.h>), which hides
+# everything C99 added to the C library, even in C++ mode. libc++ needs some of those
+# additions to provide a conforming library at all.
+# UNSUPPORTED: freebsd
 
 # RUN: %{python} %s %{libcxx-dir}/utils
 # END.