Compile warning with strchrnul in macOS 15.4

[Explorer09]

./XUtils.h:92:11: warning: 'strchrnul' is only available on macOS 15.4 or newer [-Wunguarded-availability-new]
   92 |    return strchrnul(s, c);
      |           ^~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/_string.h:198:9: note: 'strchrnul' has been marked as being introduced in macOS 15.4 here, but the deployment target is macOS 15.0.0
  198 |         strchrnul(const char *__s, int __c);
      |         ^

And we are not alone in encountering this warning.

sqlc-dev/sqlc#3916
https://www.postgresql.org/message-id/E1tziZ6-002AW9-2C%40gemulon.postgresql.org

[BenBE]

As some systems don't have it, we could fall back to use our internal implementation in that case. Mind to write a quick PR?

[Explorer09]

@BenBE I was asking for some ideas for the fix before I try to make one for me. This compatibility problem sounds like a new one (and it's macOS exclusive)

It's because macOS 15.4 (Sequoia) does ship with strchrnul in it's standard library, but the macOS SDK that comes with macOS 15.4 defaults to building for macOS 15.0, which does not have strchrnul.

For me, there are two changes needed here:

1. We need to check strchrnul with a header include now. Can't just use AC_CHECK_FUNCS that checks the function by linking without the header.
2. We need to inform the builder (one who runs configure) about the MACOSX_DEPLOYMENT_TARGET in the config result. This can reduce surprise when the users find that certain functions are disabled / not used during the build.

[BenBE]

The changes for configure.ac in the pgsql source seem reasonable:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=a39eb9c77faaf51f8d02da718546e77e00a7622a

The important part of that diff is the following section:

diff --git a/configure.ac b/configure.ac
index e2d8ca9f1a0d8dc0db3767c11105fa0879cdba24..e7cd4de01639d42404ba54088ad01b461eb2ef96 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1809,7 +1809,6 @@ AC_CHECK_FUNCS(m4_normalize([
    pthread_is_threaded_np
    setproctitle
    setproctitle_fast
-   strchrnul
    strsignal
    syncfs
    sync_file_range
@@ -1849,6 +1848,7 @@ AC_CHECK_DECLS([strlcat, strlcpy, strnlen])
 # won't handle deployment target restrictions on macOS
 AC_CHECK_DECLS([preadv], [], [AC_LIBOBJ(preadv)], [#include <sys/uio.h>])
 AC_CHECK_DECLS([pwritev], [], [AC_LIBOBJ(pwritev)], [#include <sys/uio.h>])
+AC_CHECK_DECLS([strchrnul], [], [], [#include <string.h>])
 
 # This is probably only present on macOS, but may as well check always
 AC_CHECK_DECLS(F_FULLFSYNC, [], [], [#include <fcntl.h>])

[Explorer09]

I think I'll leave out the second suggested change as it's more of a usability feature than a necessary bug fix. The -mmacos-version-min option specified by the builder can be checked by the predefined macro __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ when compiling a source file, but there would parsing needed to transform the value to a human readable text. The work would be non-trivial in configure.

/* Default value for macOS SDK in macOS Sequoia (15.x) */
#define __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ 150000
/* If -mmacos-version-min=15.1 is specified in CFLAGS */
#define __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ 150100