Fix setting a range of char-table slots in a singular case

* src/chartab.c (char_table_set_range): Start the loop from the
first character of the block to which FROM belongs.  (Bug#23797)

* test/src/chartab-tests.el: New test file.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/chartab.c b/src/chartab.c
index 6cf8fea0b6d..fa5a8e41164 100644
--- a/src/chartab.c
+++ b/src/chartab.c
@@ -492,7 +492,7 @@ char_table_set_range (Lisp_Object table, int from, int to, Lisp_Object val)
       int lim = CHARTAB_IDX (to, 0, 0);
       int i, c;
 
-      for (i = CHARTAB_IDX (from, 0, 0), c = 0; i <= lim;
+      for (i = CHARTAB_IDX (from, 0, 0), c = i * chartab_chars[0]; i <= lim;
            i++, c += chartab_chars[0])
         {
           if (c > to)