Add a "fork" of musl as //fusl.

fusl/src/math/sinhl.c

+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double sinhl(long double x)
+{
+        return sinh(x);
+}
+#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+long double sinhl(long double x)
+{
+        union ldshape u = {x};
+        unsigned ex = u.i.se & 0x7fff;
+        long double h, t, absx;
+
+        h = 0.5;
+        if (u.i.se & 0x8000)
+                h = -h;
+        /* |x| */
+        u.i.se = ex;
+        absx = u.f;
+
+        /* |x| < log(LDBL_MAX) */
+        if (ex < 0x3fff+13 || (ex == 0x3fff+13 && u.i.m>>32 < 0xb17217f7)) {
+                t = expm1l(absx);
+                if (ex < 0x3fff) {
+                        if (ex < 0x3fff-32)
+                                return x;
+                        return h*(2*t - t*t/(1+t));
+                }
+                return h*(t + t/(t+1));
+        }
+
+        /* |x| > log(LDBL_MAX) or nan */
+        t = expl(0.5*absx);
+        return h*t*t;
+}
+#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
+// TODO: broken implementation to make things compile
+long double sinhl(long double x)
+{
+        return sinh(x);
+}
+#endif