From c4dff961f0655d6ee3fffb29631433dc804f9eaa Mon Sep 17 00:00:00 2001
From: Adamas <bud-adamas@users.noreply.github.com>
Date: Fri, 27 Dec 2019 10:00:01 +0800
Subject: [PATCH] eliminate the warnings

if there is no `dyn`, there are warnings like this:
        warning: trait objects without an explicit `dyn` are deprecated
        --> xxx.rs:5:45
        |
        5 | type Result<T> = std::result::Result<T, Box<error::Error>>;
        |                                             ^^^^^^^^^^^^ help: use `dyn`: `dyn error::Error`
        |
        = note: `#[warn(bare_trait_objects)]` on by default

        warning: trait objects without an explicit `dyn` are deprecated
        --> xxx.rs:21:32
        |
        21 |     fn cause(&self) -> Option<&error::Error> {
        |                                ^^^^^^^^^^^^ help: use `dyn`: `dyn error::Error`
---
 src/error/multiple_error_types/boxing_errors.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/error/multiple_error_types/boxing_errors.md b/src/error/multiple_error_types/boxing_errors.md
index e2eb68607e..b0fc2aa3ec 100644
--- a/src/error/multiple_error_types/boxing_errors.md
+++ b/src/error/multiple_error_types/boxing_errors.md
@@ -13,7 +13,7 @@ use std::error;
 use std::fmt;
 
 // Change the alias to `Box<error::Error>`.
-type Result<T> = std::result::Result<T, Box<error::Error>>;
+type Result<T> = std::result::Result<T, Box<dyn error::Error>>;
 
 #[derive(Debug, Clone)]
 struct EmptyVec;
@@ -29,7 +29,7 @@ impl error::Error for EmptyVec {
         "invalid first item to double"
     }
 
-    fn cause(&self) -> Option<&error::Error> {
+    fn cause(&self) -> Option<&(dyn error::Error)> {
         // Generic error, underlying cause isn't tracked.
         None
     }