vim-patch:8.1.1475: search string not displayed when 'rightleft' is set

Problem:    Search string not displayed when 'rightleft' is set.
Solution:   Clear the right part of the old text. (closes vim/vim#4488, closes vim/vim#4489)
db294adc65

src/nvim/search.c

@@ -1218,9 +1218,14 @@ int do_search(
           while (*r != NUL && *r == ' ') {
             r++;
           }
-          memmove(msgbuf, r, msgbuf + STRLEN(msgbuf) - r);
+          size_t pat_len = msgbuf + STRLEN(msgbuf) - r;
+          memmove(msgbuf, r, pat_len);
           // overwrite old text
-          memset(r, ' ', msgbuf + STRLEN(msgbuf) - r);
+          if ((size_t)(r - msgbuf) >= pat_len) {
+            memset(r, ' ', pat_len);
+          } else {
+            memset(msgbuf + pat_len, ' ', r - msgbuf);
+          }
         }
         msg_outtrans(msgbuf);
         msg_clr_eos();

src/nvim/testdir/test_search.vim

@@ -609,3 +609,25 @@ func Test_search_match_at_curpos()
 
   close!
 endfunc
+
+func Test_search_display_pattern()
+  new
+  call setline(1, ['foo', 'bar', 'foobar'])
+
+  call cursor(1, 1)
+  let @/ = 'foo'
+  let pat = escape(@/, '()*?'. '\s\+')
+  let g:a = execute(':unsilent :norm! n')
+  call assert_match(pat, g:a)
+
+  " right-left
+  if exists("+rightleft")
+    set rl
+    call cursor(1, 1)
+    let @/ = 'foo'
+    let pat = 'oof/\s\+'
+    let g:a = execute(':unsilent :norm! n')
+    call assert_match(pat, g:a)
+    set norl
+  endif
+endfunc