Rollup merge of #54848 - davidtwco:issue-52663-trait-object, r=nikomatsakis

Fixes #47311.
r? @nrc

src/test/ui/nll/issue-52663-trait-object.rs

@@ -0,0 +1,27 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(box_syntax)]
+#![feature(nll)]
+
+trait Foo { fn get(&self); }
+
+impl<A> Foo for A {
+    fn get(&self) { }
+}
+
+fn main() {
+    let _ = {
+        let tmp0 = 3;
+        let tmp1 = &tmp0;
+        box tmp1 as Box<Foo + '_>
+    };
+    //~^^^ ERROR `tmp0` does not live long enough
+}

src/test/ui/nll/issue-52663-trait-object.stderr

@@ -0,0 +1,13 @@
+error[E0597]: `tmp0` does not live long enough
+  --> $DIR/issue-52663-trait-object.rs:23:20
+   |
+LL |         let tmp1 = &tmp0;
+   |                    ^^^^^ borrowed value does not live long enough
+LL |         box tmp1 as Box<Foo + '_>
+   |         ------------------------- borrow later captured here by trait object
+LL |     };
+   |     - `tmp0` dropped here while still borrowed
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0597`.

src/test/ui/span/regions-close-over-type-parameter-2.nll.stderr

@@ -4,7 +4,7 @@ error[E0597]: `tmp0` does not live long enough
 LL |         let tmp1 = &tmp0;
    |                    ^^^^^ borrowed value does not live long enough
 LL |         repeater3(tmp1)
-   |         --------------- borrow later used here
+   |         --------------- borrow later captured here by trait object
 LL |     };
    |     - `tmp0` dropped here while still borrowed