Auto merge of #44008 - RalfJung:staged1, r=alexcrichton

Make sure crates not opting in to staged_api don't use staged_api

This also fixes the problem that with `-Zforce-unstable-if-unmarked` set, crates could not use `#[deprecated]`.

If you prefer, I can instead submit another version which just fixes this problem, but still allows the staged API attributes for all crates when  `-Zforce-unstable-if-unmarked` is set. I have prepared that at <https://github.com/RalfJung/rust/tree/staged2>. As yet another alternative, @alexcrichton suggested to turn this error into a lint, but that seems to be much more work, so is it worth it?

Cc @alexcrichton #43975

src/librustc/middle/stability.rs

@@ -123,7 +123,8 @@ impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
                    item_sp: Span, kind: AnnotationKind, visit_children: F)
         where F: FnOnce(&mut Self)
     {
-        if self.index.staged_api[&LOCAL_CRATE] {
+        if self.tcx.sess.features.borrow().staged_api {
+            // This crate explicitly wants staged API.
             debug!("annotate(id = {:?}, attrs = {:?})", id, attrs);
             if let Some(..) = attr::find_deprecation(self.tcx.sess.diagnostic(), attrs, item_sp) {
                 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged api, \
@@ -204,6 +205,15 @@ impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
                 }
             }
 
+            // Propagate unstability.  This can happen even for non-staged-api crates in case
+            // -Zforce-unstable-if-unmarked is set.
+            if let Some(stab) = self.parent_stab {
+                if stab.level.is_unstable() {
+                    let def_id = self.tcx.hir.local_def_id(id);
+                    self.index.stab_map.insert(def_id, Some(stab));
+                }
+            }
+
             if let Some(depr) = attr::find_deprecation(self.tcx.sess.diagnostic(), attrs, item_sp) {
                 if kind == AnnotationKind::Prohibited {
                     self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");

src/librustc_plugin/lib.rs

@@ -69,6 +69,7 @@
 #![deny(warnings)]
 
 #![feature(rustc_diagnostic_macros)]
+#![feature(staged_api)]
 
 #[macro_use] extern crate syntax;
 

src/libtest/lib.rs

@@ -37,6 +37,7 @@
 #![feature(libc)]
 #![feature(set_stdio)]
 #![feature(panic_unwind)]
+#![feature(staged_api)]
 
 extern crate getopts;
 extern crate term;

src/test/compile-fail/stability-attribute-non-staged-force-unstable.rs

@@ -0,0 +1,16 @@
+// Copyright 2015 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.
+
+// compile-flags:-Zforce-unstable-if-unmarked
+
+#[unstable] //~ ERROR: stability attributes may not be used
+#[stable] //~ ERROR: stability attributes may not be used
+#[rustc_deprecated] //~ ERROR: stability attributes may not be used
+fn main() { }

src/test/run-pass/deprecation-in-force-unstable.rs

@@ -0,0 +1,14 @@
+// Copyright 2015 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.
+
+// compile-flags:-Zforce-unstable-if-unmarked
+
+#[deprecated] // should work even with -Zforce-unstable-if-unmarked
+fn main() { }