Fix portability of bignum in ISeq Binary Format

- Unless `sizeof(BDIGIT) == 4`, (8-byte integer not available), the
  size to be loaded was wrong.
- Since `BDIGIT`s are dumped as raw binary, the loaded byte order was
  inverted unless little-endian.

1 files changed, 6 insertions, 2 deletions

diff --git a/compile.c b/compile.c
index 6038a22723..7e8b6c37b8 100644
--- a/compile.c
+++ b/compile.c
@@ -12859,8 +12859,12 @@ ibf_load_object_bignum(const struct ibf_load *load, const struct ibf_object_head
     const struct ibf_object_bignum *bignum = IBF_OBJBODY(struct ibf_object_bignum, offset);
     int sign = bignum->slen > 0;
     ssize_t len = sign > 0 ? bignum->slen : -1 * bignum->slen;
-    VALUE obj = rb_integer_unpack(bignum->digits, len * 2, 2, 0,
-                                  INTEGER_PACK_LITTLE_ENDIAN | (sign == 0 ? INTEGER_PACK_NEGATIVE : 0));
+    const int big_unpack_flags = /* c.f. rb_big_unpack() */
+        INTEGER_PACK_LSWORD_FIRST |
+        INTEGER_PACK_NATIVE_BYTE_ORDER;
+    VALUE obj = rb_integer_unpack(bignum->digits, len, sizeof(BDIGIT), 0,
+                                  big_unpack_flags |
+                                  (sign == 0 ? INTEGER_PACK_NEGATIVE : 0));
     if (header->internal) rb_obj_hide(obj);
     if (header->frozen)   rb_obj_freeze(obj);
     return obj;