Make number-to-string work for bignums

* src/data.c (Fnumber_to_string): Handle bignum.
* test/src/data-tests.el (data-tests-number-to-string): New test.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/data.c b/src/data.c
index b49daabe85d..18b572de977 100644
--- a/src/data.c
+++ b/src/data.c
@@ -2756,6 +2756,14 @@ NUMBER may be an integer or a floating point number.  */)
   char buffer[max (FLOAT_TO_STRING_BUFSIZE, INT_BUFSIZE_BOUND (EMACS_INT))];
   int len;
 
+  if (BIGNUMP (number))
+    {
+      ptrdiff_t count = SPECPDL_INDEX ();
+      char *str = mpz_get_str (NULL, 10, XBIGNUM (number)->value);
+      record_unwind_protect_ptr (xfree, str);
+      return unbind_to (count, make_unibyte_string (str, strlen (str)));
+    }
+
   CHECK_FIXNUM_OR_FLOAT (number);
 
   if (FLOATP (number))