patch 8.1.0571: non-silent execute() resets display column to zero

Problem:    Non-silent execute() resets display column to zero.
Solution:   Keep the display column as-is.

src/evalfunc.c

@@ -3263,6 +3263,7 @@ f_execute(typval_T *argvars, typval_T *rettv)
     int		save_redir_off = redir_off;
     garray_T	save_ga;
     int		save_msg_col = msg_col;
+    int		echo_output = FALSE;
 
     rettv->vval.v_string = NULL;
     rettv->v_type = VAR_STRING;
@@ -3289,6 +3290,8 @@ f_execute(typval_T *argvars, typval_T *rettv)
 
 	if (s == NULL)
 	    return;
+	if (*s == NUL)
+	    echo_output = TRUE;
 	if (STRNCMP(s, "silent", 6) == 0)
 	    ++msg_silent;
 	if (STRCMP(s, "silent!") == 0)
@@ -3305,7 +3308,8 @@ 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 (!echo_output)
+	msg_col = 0;  // prevent leading spaces
 
     if (cmd != NULL)
 	do_cmdline_cmd(cmd);
@@ -3339,8 +3343,14 @@ f_execute(typval_T *argvars, typval_T *rettv)
     redir_off = save_redir_off;
 
     // "silent reg" or "silent echo x" leaves msg_col somewhere in the line.
-    // Put it back where it was, since nothing should have been written.
+    if (echo_output)
-    msg_col = save_msg_col;
+	// When not working silently: put it in column zero.  A following
+	// "echon" will overwrite the message, unavoidably.
+	msg_col = 0;
+    else
+	// When working silently: Put it back where it was, since nothing
+	// should have been written.
+	msg_col = save_msg_col;
 }
 
 /*

src/testdir/test_execute_func.vim

@@ -61,3 +61,20 @@ func Test_execute_does_not_change_col()
   endfor
   call assert_equal('abcdxyz', text)
 endfunc
+
+func Test_execute_not_silent()
+  echo ''
+  echon 'abcd'
+  let x = execute('echon 234', '')
+  echo 'xyz'
+  let text1 = ''
+  for col in range(1, 8)
+    let text1 .= nr2char(screenchar(&lines - 1, col))
+  endfor
+  call assert_equal('abcd234 ', text1)
+  let text2 = ''
+  for col in range(1, 4)
+    let text2 .= nr2char(screenchar(&lines, col))
+  endfor
+  call assert_equal('xyz ', text2)
+endfunc

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    571,
 /**/
     570,
 /**/