auto merge of #17501 : pcwalton/rust/improve-method-lookup-autoderef, r=nikomatsakis

prefer `Deref` over `DerefMut` in all other circumstances.

Because the compiler now prefers `Deref`, this can break code that
looked like:

    let mut foo = bar.borrow_mut();
    (*foo).call_something_that_requires_mutable_self();

Replace this code with:

    let mut foo = bar.baz();
    (&mut *foo).call_something_that_requires_mutable_self();

Closes #12825.

[breaking-change]

r? @nikomatsakis

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libgreen/basic.rs b/src/libgreen/basic.rs
index 27c71cb3e7c..129d37638a3 100644
--- a/src/libgreen/basic.rs
+++ b/src/libgreen/basic.rs
@@ -116,7 +116,7 @@ impl EventLoop for BasicLoop {
             }
 
             unsafe {
-                let mut messages = self.messages.lock();
+                let messages = self.messages.lock();
                 // We block here if we have no messages to process and we may
                 // receive a message at a later date
                 if self.remotes.len() > 0 && messages.len() == 0 &&