Re: PG 17.2 compilation fails with -std=c11 on mac - Mailing list pgsql-hackers

I wrote:
> We lack that #define, which results in <string.h> not supplying
> the declaration.  AFAICT the requirement for this is in the C11
> standard, this is not just Apple doing something weird.
> Aside from this compilation error, we're probably failing to use
> memset_s on some platforms where it's available, for lack of
> the #define in our configure/meson probes.  I know how to fix
> that in configure, but I'm less clear on how nonstandard probes
> work in meson --- any help there?

Here's a lightly-tested fix for that (against HEAD, but it likely
works on v17 too).

            regards, tom lane

diff --git a/configure b/configure
index 275c67ee67c..4f15347cc95 100755
--- a/configure
+++ b/configure
@@ -15616,7 +15616,7 @@ fi
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`

-for ac_func in backtrace_symbols copyfile copy_file_range elf_aux_info getauxval getifaddrs getpeerucred inet_pton
kqueuelocaleconv_l mbstowcs_l memset_s posix_fallocate ppoll pthread_is_threaded_np setproctitle setproctitle_fast
strsignalsyncfs sync_file_range uselocale wcstombs_l 
+for ac_func in backtrace_symbols copyfile copy_file_range elf_aux_info getauxval getifaddrs getpeerucred inet_pton
kqueuelocaleconv_l mbstowcs_l posix_fallocate ppoll pthread_is_threaded_np setproctitle setproctitle_fast strsignal
syncfssync_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"
@@ -16192,6 +16192,19 @@ cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_STRCHRNUL $ac_have_decl
 _ACEOF

+ac_fn_c_check_decl "$LINENO" "memset_s" "ac_cv_have_decl_memset_s" "#define __STDC_WANT_LIB_EXT1__ 1
+#include <string.h>
+"
+if test "x$ac_cv_have_decl_memset_s" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_MEMSET_S $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>
diff --git a/configure.ac b/configure.ac
index 7ea91d56adb..4b8335dc613 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1792,7 +1792,6 @@ AC_CHECK_FUNCS(m4_normalize([
     kqueue
     localeconv_l
     mbstowcs_l
-    memset_s
     posix_fallocate
     ppoll
     pthread_is_threaded_np
@@ -1838,6 +1837,8 @@ AC_CHECK_DECLS([strlcat, strlcpy, strnlen, strsep, timingsafe_bcmp])
 AC_CHECK_DECLS([preadv], [], [], [#include <sys/uio.h>])
 AC_CHECK_DECLS([pwritev], [], [], [#include <sys/uio.h>])
 AC_CHECK_DECLS([strchrnul], [], [], [#include <string.h>])
+AC_CHECK_DECLS([memset_s], [], [], [#define __STDC_WANT_LIB_EXT1__ 1
+#include <string.h>])

 # This is probably only present on macOS, but may as well check always
 AC_CHECK_DECLS(F_FULLFSYNC, [], [], [#include <fcntl.h>])
diff --git a/meson.build b/meson.build
index 12de5e80c31..d142e3e408b 100644
--- a/meson.build
+++ b/meson.build
@@ -2654,6 +2654,7 @@ decl_checks += [
   ['preadv', 'sys/uio.h'],
   ['pwritev', 'sys/uio.h'],
   ['strchrnul', 'string.h'],
+  ['memset_s', 'string.h', '#define __STDC_WANT_LIB_EXT1__ 1'],
 ]

 # Check presence of some optional LLVM functions.
@@ -2667,21 +2668,23 @@ endif
 foreach c : decl_checks
   func = c.get(0)
   header = c.get(1)
-  args = c.get(2, {})
+  prologue = c.get(2, '')
+  args = c.get(3, {})
   varname = 'HAVE_DECL_' + func.underscorify().to_upper()

   found = cc.compiles('''
-#include <@0@>
+@0@
+#include <@1@>

 int main()
 {
-#ifndef @1@
-    (void) @1@;
+#ifndef @2@
+    (void) @2@;
 #endif

 return 0;
 }
-'''.format(header, func),
+'''.format(prologue, 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
@@ -2880,7 +2883,6 @@ func_checks = [
   ['kqueue'],
   ['localeconv_l'],
   ['mbstowcs_l'],
-  ['memset_s'],
   ['mkdtemp'],
   ['posix_fadvise'],
   ['posix_fallocate'],
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index c3cc9fa856d..726a7c1be1f 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -91,6 +91,10 @@
    `LLVMCreatePerfJITEventListener', and to 0 if you don't. */
 #undef HAVE_DECL_LLVMCREATEPERFJITEVENTLISTENER

+/* Define to 1 if you have the declaration of `memset_s', and to 0 if you
+   don't. */
+#undef HAVE_DECL_MEMSET_S
+
 /* Define to 1 if you have the declaration of `posix_fadvise', and to 0 if you
    don't. */
 #undef HAVE_DECL_POSIX_FADVISE
@@ -291,9 +295,6 @@
 /* Define to 1 if you have the <memory.h> header file. */
 #undef HAVE_MEMORY_H

-/* Define to 1 if you have the `memset_s' function. */
-#undef HAVE_MEMSET_S
-
 /* Define to 1 if you have the `mkdtemp' function. */
 #undef HAVE_MKDTEMP

diff --git a/src/port/explicit_bzero.c b/src/port/explicit_bzero.c
index 1d37b119bab..358a692f357 100644
--- a/src/port/explicit_bzero.c
+++ b/src/port/explicit_bzero.c
@@ -12,9 +12,11 @@
  *-------------------------------------------------------------------------
  */

+#define __STDC_WANT_LIB_EXT1__ 1        /* needed to access memset_s() */
+
 #include "c.h"

-#if defined(HAVE_MEMSET_S)
+#if HAVE_DECL_MEMSET_S

 void
 explicit_bzero(void *buf, size_t len)