+dnl --------------------------------------------------------------------
+dnl Check for MSVC
+AC_DEFUN([OL_MSVC],
+[AC_REQUIRE_CPP()dnl
+AC_CACHE_CHECK([whether we are using MS Visual C++], ol_cv_msvc,
+[AC_PREPROC_IFELSE([AC_LANG_SOURCE([[
+#ifndef _MSC_VER
+#include <__FOO__/generate_error.h>
+#endif
+]])],[ol_cv_msvc=yes],[ol_cv_msvc=no])])])
+