Fix detection and handling of strchrnul() for macOS 15.4.

configure

@@ -15801,7 +15801,7 @@ fi
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-for ac_func in backtrace_symbols copyfile getifaddrs getpeerucred inet_pton kqueue mbstowcs_l memset_s posix_fallocate ppoll pthread_is_threaded_np setproctitle setproctitle_fast strchrnul strsignal syncfs sync_file_range uselocale wcstombs_l
+for ac_func in backtrace_symbols copyfile getifaddrs getpeerucred inet_pton kqueue mbstowcs_l memset_s posix_fallocate ppoll pthread_is_threaded_np setproctitle setproctitle_fast strsignal syncfs sync_file_range uselocale wcstombs_l
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
@@ -16365,6 +16365,18 @@ esac
 
 fi
 
+ac_fn_c_check_decl "$LINENO" "strchrnul" "ac_cv_have_decl_strchrnul" "#include <string.h>
+"
+if test "x$ac_cv_have_decl_strchrnul" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRCHRNUL $ac_have_decl
+_ACEOF
+
 
 # This is probably only present on macOS, but may as well check always
 ac_fn_c_check_decl "$LINENO" "F_FULLFSYNC" "ac_cv_have_decl_F_FULLFSYNC" "#include <fcntl.h>

configure.ac

@@ -1822,7 +1822,6 @@ AC_CHECK_FUNCS(m4_normalize([
 	pthread_is_threaded_np
 	setproctitle
 	setproctitle_fast
-	strchrnul
 	strsignal
 	syncfs
 	sync_file_range
@@ -1862,6 +1861,7 @@ 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>])

meson.build

@@ -2323,6 +2323,7 @@ decl_checks = [
 decl_checks += [
   ['preadv', 'sys/uio.h'],
   ['pwritev', 'sys/uio.h'],
+  ['strchrnul', 'string.h'],
 ]
 
 foreach c : decl_checks
@@ -2331,8 +2332,23 @@ foreach c : decl_checks
   args = c.get(2, {})
   varname = 'HAVE_DECL_' + func.underscorify().to_upper()
 
-  found = cc.has_header_symbol(header, func,
-    args: test_c_args, include_directories: postgres_inc,
+  found = cc.compiles('''
+#include <@0@>
+
+int main()
+{
+#ifndef @1@
+    (void) @1@;
+#endif
+
+return 0;
+}
+'''.format(header, func),
+    name: 'test whether @0@ is declared'.format(func),
+    # need to add cflags_warn to get at least
+    # -Werror=unguarded-availability-new if applicable
+    args: test_c_args + cflags_warn,
+    include_directories: postgres_inc,
     kwargs: args)
   cdata.set10(varname, found, description:
 '''Define to 1 if you have the declaration of `@0@', and to 0 if you
@@ -2579,7 +2595,6 @@ func_checks = [
   ['shm_unlink', {'dependencies': [rt_dep], 'define': false}],
   ['shmget', {'dependencies': [cygipc_dep], 'define': false}],
   ['socket', {'dependencies': [socket_dep], 'define': false}],
-  ['strchrnul'],
   ['strerror_r', {'dependencies': [thread_dep]}],
   ['strlcat'],
   ['strlcpy'],

src/include/pg_config.h.in

@@ -128,6 +128,10 @@
    don't. */
 #undef HAVE_DECL_PWRITEV
 
+/* Define to 1 if you have the declaration of `strchrnul', and to 0 if you
+   don't. */
+#undef HAVE_DECL_STRCHRNUL
+
 /* Define to 1 if you have the declaration of `strlcat', and to 0 if you
    don't. */
 #undef HAVE_DECL_STRLCAT
@@ -412,9 +416,6 @@
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H
 
-/* Define to 1 if you have the `strchrnul' function. */
-#undef HAVE_STRCHRNUL
-
 /* Define to 1 if you have the `strerror_r' function. */
 #undef HAVE_STRERROR_R
 

src/port/snprintf.c

@@ -338,13 +338,22 @@ static void leading_pad(int zpad, int signvalue, int *padlen,
 static void trailing_pad(int padlen, PrintfTarget *target);
 
 /*
- * If strchrnul exists (it's a glibc-ism), it's a good bit faster than the
- * equivalent manual loop.  If it doesn't exist, provide a replacement.
+ * If strchrnul exists (it's a glibc-ism, but since adopted by some other
+ * platforms), it's a good bit faster than the equivalent manual loop.
+ * Use it if possible, and if it doesn't exist, use this replacement.
  *
  * Note: glibc declares this as returning "char *", but that would require
  * casting away const internally, so we don't follow that detail.
+ *
+ * Note: macOS has this too as of Sequoia 15.4, but it's hidden behind
+ * a deployment-target check that causes compile errors if the deployment
+ * target isn't high enough.  So !HAVE_DECL_STRCHRNUL may mean "yes it's
+ * declared, but it doesn't compile".  To avoid failing in that scenario,
+ * use a macro to avoid matching <string.h>'s name.
  */
-#ifndef HAVE_STRCHRNUL
+#if !HAVE_DECL_STRCHRNUL
+
+#define strchrnul pg_strchrnul
 
 static inline const char *
 strchrnul(const char *s, int c)
@@ -354,19 +363,7 @@ strchrnul(const char *s, int c)
 	return s;
 }
 
-#else
-
-/*
- * glibc's <string.h> declares strchrnul only if _GNU_SOURCE is defined.
- * While we typically use that on glibc platforms, configure will set
- * HAVE_STRCHRNUL whether it's used or not.  Fill in the missing declaration
- * so that this file will compile cleanly with or without _GNU_SOURCE.
- */
-#ifndef _GNU_SOURCE
-extern char *strchrnul(const char *s, int c);
-#endif
-
-#endif							/* HAVE_STRCHRNUL */
+#endif							/* !HAVE_DECL_STRCHRNUL */
 
 
 /*

src/tools/msvc/Solution.pm

@@ -241,6 +241,7 @@ sub GenerateFiles
 		HAVE_DECL_POSIX_FADVISE => 0,
 		HAVE_DECL_PREADV => 0,
 		HAVE_DECL_PWRITEV => 0,
+		HAVE_DECL_STRCHRNUL => 0,
 		HAVE_DECL_STRLCAT => 0,
 		HAVE_DECL_STRLCPY => 0,
 		HAVE_DECL_STRNLEN => 1,
@@ -332,7 +333,6 @@ sub GenerateFiles
 		HAVE_SSL_CTX_SET_NUM_TICKETS => undef,
 		HAVE_STDINT_H => 1,
 		HAVE_STDLIB_H => 1,
-		HAVE_STRCHRNUL => undef,
 		HAVE_STRERROR_R => undef,
 		HAVE_STRINGS_H => undef,
 		HAVE_STRING_H => 1,