patch 8.0.1217: can't use remote eval to inspect vars in debug mode

Problem:    Can't use remote eval to inspect vars in debug mode.
Solution:   Don't discard the call stack in debug mode. (closes #2237, #2247)

src/ex_cmds2.c

@@ -131,6 +131,7 @@ do_debug(char_u *cmd)
     redir_off = TRUE;		/* don't redirect debug commands */
 
     State = NORMAL;
+    debug_mode = TRUE;
 
     if (!debug_did_msg)
 	MSG(_("Entering Debug mode.  Type \"cont\" to continue."));
@@ -319,6 +320,7 @@ do_debug(char_u *cmd)
     msg_scroll = save_msg_scroll;
     lines_left = Rows - 1;
     State = save_State;
+    debug_mode = FALSE;
     did_emsg = save_did_emsg;
     cmd_silent = save_cmd_silent;
     msg_silent = save_msg_silent;

src/globals.h

@@ -922,9 +922,13 @@ EXTERN char_u		composing_hangul_buffer[5];
  * "Visual_mode"    When State is NORMAL or INSERT.
  * "finish_op"	    When State is NORMAL, after typing the operator and before
  *		    typing the motion command.
+ * "debug_mode"	    Debug mode.
  */
 EXTERN int	State INIT(= NORMAL);	/* This is the current state of the
 					 * command interpreter. */
+#ifdef FEAT_EVAL
+EXTERN int	debug_mode INIT(= FALSE);
+#endif
 
 EXTERN int	finish_op INIT(= FALSE);/* TRUE while an operator is pending */
 EXTERN long	opcount INIT(= 0);	/* count for pending operator */

src/main.c

@@ -4180,10 +4180,11 @@ eval_client_expr_to_string(char_u *expr)
     char_u	*res;
     int		save_dbl = debug_break_level;
     int		save_ro = redir_off;
-    void	*fc;
+    void	*fc = NULL;
 
     /* Evaluate the expression at the toplevel, don't use variables local to
-     * the calling function. */
+     * the calling function. Except when in debug mode. */
+    if (!debug_mode)
 	fc = clear_current_funccal();
 
      /* Disable debugging, otherwise Vim hangs, waiting for "cont" to be
@@ -4201,6 +4202,7 @@ eval_client_expr_to_string(char_u *expr)
     --emsg_silent;
     if (emsg_silent < 0)
 	emsg_silent = 0;
+    if (fc != NULL)
 	restore_current_funccal(fc);
 
     /* A client can tell us to redraw, but not to display the cursor, so do

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1217,
 /**/
     1216,
 /**/