Auto merge of #37128 - nrc:depr-attr, r=@alexcrichton

Deprecate no_debug and custom_derive

r? @nikomatsakis

src/test/compile-fail/deriving-meta-unknown-trait.rs

@@ -8,8 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// ignore-tidy-linelength
+
 #[derive(Eqr)]
-//~^ ERROR `#[derive]` for custom traits is not stable enough for use and is subject to change
+//~^ ERROR `#[derive]` for custom traits is not stable enough for use. It is deprecated and will be removed in v1.15 (see issue #29644)
 struct Foo;
 
 pub fn main() {}

src/test/compile-fail/feature-gate-no-debug-2.rs

@@ -0,0 +1,15 @@
+// Copyright 2016 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.
+
+#![deny(deprecated)]
+#![feature(no_debug)]
+
+#[no_debug] //~ ERROR use of deprecated attribute `no_debug`
+fn main() {}