Add optional description which complains on newer versions of autoconf

Summary: https://github.com/facebook/folly/pull/22

Test Plan: none

Reviewed By: andrewjcg@fb.com

FB internal diff: D683791

diff --git a/folly/configure.ac b/folly/configure.ac
index 6d564f9fa95c2b919aa514b27dd83c9450c35447..13efcbe25112c657ae9f244d6b139c255727ade1 100644 (file)
--- a/folly/configure.ac
+++ b/folly/configure.ac
@@ -52,8 +52,8 @@ AC_TYPE_SIZE_T
 AC_HEADER_TIME
 AC_C_VOLATILE
 AC_CHECK_TYPE([__int128],
-  [AC_DEFINE([HAVE_INT128_T], [1])],
-  [AC_DEFINE([HAVE_INT128_T], [0])])
+  [AC_DEFINE([HAVE_INT128_T], [1], [Define if __int128 exists])],
+  [AC_DEFINE([HAVE_INT128_T], [0], [Define if __int128 does not exist])])
 AC_CHECK_TYPES([ptrdiff_t])
 
 # Checks for library functions.