vim-patch:8.2.0112: illegal memory access when using 'cindent'

Problem:    Illegal memory access when using 'cindent'.
Solution:   Check for NUL byte. (Dominique Pelle, closes vim/vim#5470)
02ad46394e

src/nvim/indent_c.c

@@ -461,6 +461,9 @@ cin_iscase (
   if (cin_starts_with(s, "case")) {
     for (s += 4; *s; ++s) {
       s = cin_skipcomment(s);
+      if (*s == NUL) {
+        break;
+      }
       if (*s == ':') {
         if (s[1] == ':')                /* skip over "::" for C++ */
           ++s;

src/nvim/testdir/test_cindent.vim

@@ -118,4 +118,13 @@ b = something();
   bw!
 endfunc
 
+" this was going beyond the end of the line.
+func Test_cindent_case()
+  new
+  call setline(1, "case x: // x")
+  set cindent
+  norm! f:a:
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab