Auto merge of #55385 - davidtwco:issue-55288, r=oli-obk

NLL: cast causes failure to promote to static

Fixes #55288. See commit messages for more details.

r? @oli-obk
cc @nikomatsakis
cc @pnkfelix
cc @RalfJung

src/test/ui/nll/issue-55288.rs

@@ -0,0 +1,21 @@
+// Copyright 2017 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(nll)]
+
+// run-pass
+
+struct Slice(&'static [&'static [u8]]);
+
+static MAP: Slice = Slice(&[
+    b"CloseEvent" as &'static [u8],
+]);
+
+fn main() {}