patch 8.1.0569: execute() always resets display column to zero

Problem:    Execute() always resets display column to zero. (Sha Liu)
Solution:   Don't reset it to zero, restore the previous value. (closes #3669)

src/evalfunc.c

@@ -3262,6 +3262,7 @@ f_execute(typval_T *argvars, typval_T *rettv)
     int		save_redir_execute = redir_execute;
     int		save_redir_off = redir_off;
     garray_T	save_ga;
+    int		save_msg_col = msg_col;
 
     rettv->vval.v_string = NULL;
     rettv->v_type = VAR_STRING;
@@ -3304,6 +3305,7 @@ f_execute(typval_T *argvars, typval_T *rettv)
     ga_init2(&redir_execute_ga, (int)sizeof(char), 500);
     redir_execute = TRUE;
     redir_off = FALSE;
+    msg_col = 0;  // prevent leading spaces
 
     if (cmd != NULL)
 	do_cmdline_cmd(cmd);
@@ -3336,9 +3338,9 @@ f_execute(typval_T *argvars, typval_T *rettv)
 	redir_execute_ga = save_ga;
     redir_off = save_redir_off;
 
-    /* "silent reg" or "silent echo x" leaves msg_col somewhere in the
+    // "silent reg" or "silent echo x" leaves msg_col somewhere in the line.
-     * line.  Put it back in the first column. */
+    // Put it back where it was, since nothing should have been written.
-    msg_col = 0;
+    msg_col = save_msg_col;
 }
 
 /*

src/testdir/test_execute_func.vim

@@ -49,3 +49,15 @@ func Test_execute_list()
   call assert_equal("", execute([]))
   call assert_equal("", execute(test_null_list()))
 endfunc
+
+func Test_execute_does_not_change_col()
+  echo ''
+  echon 'abcd'
+  let x = execute('silent echo 234343')
+  echon 'xyz'
+  let text = ''
+  for col in range(1, 7)
+    let text .= nr2char(screenchar(&lines, col))
+  endfor
+  call assert_equal('abcdxyz', text)
+endfunc

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    569,
 /**/
     568,
 /**/