itypes: fix broken u64_t range check.

* itypes.c (c_u64): Replace copy and pasted signed
check with the unsigned check.

1 files changed, 2 insertions, 2 deletions

diff --git a/itypes.c b/itypes.c
index 51982e66..a9126f6f 100644
--- a/itypes.c
+++ b/itypes.c
@@ -110,8 +110,8 @@ i64_t c_i64(val n, val self)
 
 u64_t c_u64(val n, val self)
 {
-  uint_ptr_t v = c_unum(n);
-  if (v < (cnum) -0x8000000000000000 || v > (cnum) 0x7FFFFFFFFFFFFFFF)
+  ucnum v = c_unum(n);
+  if (v > (ucnum) 0xFFFFFFFFFFFFFFFF)
     uw_throwf(error_s, lit("~a: value ~s is out of unsigned 64 bit range"),
               self, n, nao);
   return v;