-# copysignl.m4 serial 2
-dnl Copyright (C) 2011-2012 Free Software Foundation, Inc.
+# copysignl.m4 serial 3
+dnl Copyright (C) 2011-2013 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
+ dnl Persuade glibc <math.h> to declare copysignl().
+ AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
dnl Determine COPYSIGNL_LIBM.
gl_MATHFUNC([copysignl], [long double], [(long double, long double)])
if test $gl_cv_func_copysignl_no_libm = no \