Hi, Building PostgreSQL against the macOS 26.2 SDK (Xcode 26 beta) fails with the following error:
src/port/chklocale.c:326:8: error: call to undeclared function
'nl_langinfo_l'; ISO C99 and later do not support implicit function
declarations [-Wimplicit-function-declaration]
sys = nl_langinfo_l(CODESET, loc);
== Root Cause ==
macOS 26.2 SDK changed the structure of <langinfo.h>. In previous
SDK versions, nl_langinfo_l() was declared unconditionally. In the
new SDK, it is only exposed when _USE_EXTENDED_LOCALES_ is defined,
guarded behind a conditional include of <xlocale/_langinfo.h>:
/* macOS 26.2 SDK: langinfo.h */
#include <_langinfo.h> /* nl_langinfo() only */
#ifdef _USE_EXTENDED_LOCALES_
#include <xlocale/_langinfo.h> /* nl_langinfo_l() */
#endif
PostgreSQL's chklocale.c only includes <langinfo.h> directly, so
nl_langinfo_l() is no longer visible on macOS 26.2.
== Fix ==
Include <xlocale.h> explicitly on Apple platforms. This header
declares nl_langinfo_l() unconditionally and is the standard way
to access locale-specific extensions on macOS.
Tested on macOS 26.2 (darwin 25.3) with Apple Clang 17.
Patch attached.
Regards,
Jianghua Yang
0001-Fix-build-failure-on-macOS-26.2-SDK-due-to-missing-n.patch
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