patch 7.4.2029
Problem:    printf() does not work with 64 bit numbers.
Solution:   use the "L" length modifier. (Ken Takata)
diff --git a/src/testdir/test_expr.vim b/src/testdir/test_expr.vim
index 067dbf2..86c86c5 100644
--- a/src/testdir/test_expr.vim
+++ b/src/testdir/test_expr.vim
@@ -129,3 +129,9 @@
   call assert_equal("abcdefgi", &cpo)
   set cpo&vim
 endfunc
+
+function Test_printf_64bit()
+  if has('num64')
+    call assert_equal("123456789012345", printf('%d', 123456789012345))
+  endif
+endfunc