vim-patch:8.0.1425: execute() does not work in completion of user com…

…mand (#9317)

Problem:    execute() does not work in completion of user command. (thinca)
Solution:   Switch off redir_off and restore it. (Ozaki Kiichi, closes vim/vim#2492)
vim/vim@2095148

src/nvim/eval.c

@@ -8125,6 +8125,7 @@ static void f_execute(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   const int save_msg_silent = msg_silent;
   const int save_emsg_silent = emsg_silent;
   const bool save_emsg_noredir = emsg_noredir;
+  const bool save_redir_off = redir_off;
   garray_T *const save_capture_ga = capture_ga;
 
   if (check_secure()) {
@@ -8152,6 +8153,7 @@ static void f_execute(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   garray_T capture_local;
   ga_init(&capture_local, (int)sizeof(char), 80);
   capture_ga = &capture_local;
+  redir_off = false;
 
   if (argvars[0].v_type != VAR_LIST) {
     do_cmdline_cmd(tv_get_string(&argvars[0]));
@@ -8169,6 +8171,7 @@ static void f_execute(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   msg_silent = save_msg_silent;
   emsg_silent = save_emsg_silent;
   emsg_noredir = save_emsg_noredir;
+  redir_off = save_redir_off;
 
   ga_append(capture_ga, NUL);
   rettv->v_type = VAR_STRING;

src/nvim/testdir/test_usercommands.vim

@@ -206,3 +206,15 @@ func Test_CmdCompletion()
   com! -complete=customlist,CustomComp DoCmd :
   call assert_fails("call feedkeys(':DoCmd \<C-D>', 'tx')", 'E117:')
 endfunc
+
+func CallExecute(A, L, P)
+  " Drop first '\n'
+  return execute('echo "hi"')[1:]
+endfunc
+
+func Test_use_execute_in_completion()
+  command! -nargs=* -complete=custom,CallExecute DoExec :
+  call feedkeys(":DoExec \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"DoExec hi', @:)
+  delcommand DoExec
+endfunc