apply suggestion

Author: devnexen

Zend/Zend.m4

@@ -174,32 +174,23 @@ ZEND_CHECK_GLOBAL_REGISTER_VARIABLES
 
 case $host_os in
 darwin*)
-    dnl versions prior to this lead to compilation failure
-    min_apple_clang_train=1700.4.4.1
-
-    apple_line=`$CC --version 2>/dev/null | head -n 1`
-    echo "$apple_line" | grep -q "Apple clang" || apple_line=`$CC -v 2>&1 | head -n 1`
-
-    apple_train=`echo "$apple_line" | sed -n 's/.*(clang-\([0-9][0-9.]*\)).*/\1/p'`
-    have_preserve_none=yes
-
-    AS_IF([test -n "$apple_train"], [
-      AC_MSG_CHECKING([Apple clang build train >= $min_apple_clang_train])
-      AS_VERSION_COMPARE([$apple_train], [$min_apple_clang_train],
-        [have_preserve_none=no],
-        [],
-        []
-      )
-      AS_IF([test "x$have_preserve_none" = xyes],
-        [ZEND_CHECK_PRESERVE_NONE],
-        [AC_MSG_NOTICE([Skipping preserve_none])]
-      )
-    ], [
-      dnl Not Apple clang (could be Homebrew clang, GCC, etc.) -> keep enabled
+  dnl versions prior to this lead to compilation failure
+  dnl Prefer __apple_build_version__ (reliable, numeric) when available.
+  dnl The known-good minimum corresponds to 17000404 (see PR discussion).
+  min_apple_build_version=17000404
+  apple_build_version=`echo | $CC -dM -E -x c - 2>/dev/null | sed -n 's/^#define __apple_build_version__ \([0-9][0-9]*\)$/\1/p'`
+
+  AS_IF([test -n "$apple_build_version"], [
+    AC_MSG_CHECKING([Apple clang __apple_build_version__ >= $min_apple_build_version])
+    AS_IF([test "$apple_build_version" -ge "$min_apple_build_version"], [
+      AC_MSG_RESULT([yes])
       ZEND_CHECK_PRESERVE_NONE
-      :
     ])
-    ;;
+  ], [
+    dnl Not Apple clang (could be Homebrew clang, GCC, etc.) -> keep enabled
+    ZEND_CHECK_PRESERVE_NONE
+  ])
+;;
 *)
     ZEND_CHECK_PRESERVE_NONE
     ;;