ax_fsevents_have_file_events.m4: update to check support for FSEventS…

…treamSetDispatchQueue

m4/ax_fsevents_have_file_events.m4

@@ -8,10 +8,16 @@
 #
 # DESCRIPTION
 #
-#   This macro checks if the macOS FSEvents API supports file events.
+#   This macro checks if the macOS FSEvents API supports file events, and if it
+#   supports the FSEventStreamSetDispatchQueue function.
 #
-#   If it does, define the ax_cv_fsevents_have_file_events environment variable to
-#   "yes" and define HAVE_FSEVENTS_FILE_EVENTS.
+#   If the FSEvents API is supported, the ax_cv_fsevents_have_file_events environment
+#   variable is defined and set to "yes", and the HAVE_FSEVENTS_FILE_EVENTS symbol is
+#   defined.
+#
+#   If the FSEventStreamSetDispatchQueue function is supported, the
+#   ax_cv_fsevents_have_fseventstreamsetdispatchqueue environment variable is
+#   defined and set to "yes", and the HAVE_FSEVENTS_FILE_EVENTS symbol is defined.
 #
 # CONTRIBUTING
 #
@@ -21,14 +27,14 @@
 #
 # LICENSE
 #
-#   Copyright (c) 2014-2021 Enrico M. Crisostomo <[email protected]>
+#   Copyright (c) 2014-2022 Enrico M. Crisostomo <[email protected]>
 #
 #   Copying and distribution of this file, with or without modification, are
 #   permitted in any medium without royalty provided the copyright notice
 #   and this notice are preserved.  This file is offered as-is, without any
 #   warranty.
 
-#serial 1
+#serial 2
 
 AC_DEFUN([AX_FSEVENTS_HAVE_FILE_EVENTS],
   [AC_CACHE_CHECK(
@@ -43,11 +49,30 @@ AC_DEFUN([AX_FSEVENTS_HAVE_FILE_EVENTS],
         [ax_cv_fsevents_have_file_events=yes],
         [ax_cv_fsevents_have_file_events=no]
       )
-    AC_LANG_POP([C])])
+      AC_LANG_POP([C])])
+    AC_CACHE_CHECK(
+      [for FSEventStreamSetDispatchQueue in macOS FSEvents API],
+      ax_cv_fsevents_have_fseventstreamsetdispatchqueue,
+      [dnl
+        AC_LANG_PUSH([C])
+        AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+          [#include <CoreServices/CoreServices.h>],
+          [FSEventStreamSetDispatchQueue(NULL, NULL);]
+          )],
+          [ax_cv_fsevents_have_fseventstreamsetdispatchqueue=yes],
+          [ax_cv_fsevents_have_fseventstreamsetdispatchqueue=no]
+        )
+        AC_LANG_POP([C])])
     if test x"$ax_cv_fsevents_have_file_events" = "xyes"
     then
       AC_DEFINE(HAVE_FSEVENTS_FILE_EVENTS,
         1,
         [Define if the file events are supported by macOS FSEvents API.])
     fi
+    if test x"$ax_cv_fsevents_have_fseventstreamsetdispatchqueue" = "xyes"
+    then
+      AC_DEFINE(HAVE_FSEVENTS_FSEVENTSTREAMSETDISPATCHQUEUE,
+        1,
+        [Define if the FSEventStreamSetDispatchQueue function is supported by macOS FSEvents API.])
+    fi
   ])