1#include <math.h>
2#include <math_ldbl_opt.h>
3#undef weak_alias
4#define weak_alias(n,a)
5#define __signbitl(arg) ___signbitl(arg)
6#include <sysdeps/ieee754/ldbl-128/s_signbitl.c>
7#undef __signbitl
8#if IS_IN (libm)
9long_double_symbol (libm, ___signbitl, __signbitl);
10#else
11long_double_symbol (libc, ___signbitl, __signbitl);
12#endif
13

source code of glibc/sysdeps/ieee754/ldbl-64-128/s_signbitl.c