patch 9.0.0035: spell dump may go beyond end of an array

Problem:    Spell dump may go beyond end of an array.
Solution:   Limit the word length.

Author: brammool

src/spell.c

@@ -3996,9 +3996,10 @@ spell_dump_compl(
 		    n = arridx[depth] + curi[depth];
 		    ++curi[depth];
 		    c = byts[n];
-		    if (c == 0)
+		    if (c == 0 || depth >= MAXWLEN - 1)
 		    {
-			// End of word, deal with the word.
+			// End of word or reached maximum length, deal with the
+			// word.
 			// Don't use keep-case words in the fold-case tree,
 			// they will appear in the keep-case tree.
 			// Only use the word when the region matches.

src/testdir/test_spell.vim

@@ -285,6 +285,18 @@ func Test_spellreall()
   bwipe!
 endfunc
 
+func Test_spell_dump_word_length()
+  " this was running over MAXWLEN
+  new
+  noremap 0 0a0zW0000000
+  sil! norm 0z=0
+  sil norm 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+  sil! norm 0z=0
+
+  bwipe!
+  nunmap 0
+endfunc
+
 " Test spellsuggest({word} [, {max} [, {capital}]])
 func Test_spellsuggest()
   " Verify suggestions are given even when spell checking is not enabled.

src/version.c

@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    35,
 /**/
     34,
 /**/