Auto merge of #28420 - dominiccooney:rlsnightly, r=jdm

Update toolchain to nightly-2021-05-18

The nightly-2021-03-12 toolchain doesn't have RLS on Windows. This
breaks code completion in Visual Studio Code because the rust plugin
picks up the project toolchain.

RLS is available in all tier one platforms in nightly-2021-05-18 per:
https://rust-lang.github.io/rustup-components-history/

Signed-off-by: Dominic Cooney <dominic.cooney@gmail.com>

<!-- Please describe your changes on the following line: -->
Update toolchain to nightly-2021-05-18

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [X ] `./mach build -d` does not report any errors
- [ X] `./mach test-tidy` does not report any errors (note, except tabs/spaces issue in an unrelated file... happy to fix in this PR)
- [ ] These changes fix #___ (GitHub issue number if applicable)

<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because changing the toolchain, covered by existing tests

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

components/canvas_traits/webgl_channel/mpsc.rs

@@ -5,7 +5,6 @@
 use serde::{Deserialize, Serialize};
 use serde::{Deserializer, Serializer};
 
-#[macro_use]
 macro_rules! unreachable_serializable {
     ($name:ident) => {
         impl<T> Serialize for $name<T> {

components/devtools/actors/browsing_context.rs

@@ -125,14 +125,14 @@ pub(crate) struct BrowsingContextActor {
     pub title: RefCell<String>,
     pub url: RefCell<String>,
     pub console: String,
-    pub emulation: String,
-    pub inspector: String,
-    pub timeline: String,
-    pub profiler: String,
-    pub performance: String,
-    pub styleSheets: String,
+    pub _emulation: String,
+    pub _inspector: String,
+    pub _timeline: String,
+    pub _profiler: String,
+    pub _performance: String,
+    pub _styleSheets: String,
     pub thread: String,
-    pub tab: String,
+    pub _tab: String,
     pub streams: RefCell<HashMap<StreamId, TcpStream>>,
     pub browsing_context_id: BrowsingContextId,
     pub active_pipeline: Cell<PipelineId>,
@@ -288,13 +288,13 @@ impl BrowsingContextActor {
             title: RefCell::new(String::from(title)),
             url: RefCell::new(url.into_string()),
             console: console,
-            emulation: emulation.name(),
-            inspector: inspector.name(),
-            timeline: timeline.name(),
-            profiler: profiler.name(),
-            performance: performance.name(),
-            styleSheets: styleSheets.name(),
-            tab: tabdesc.name(),
+            _emulation: emulation.name(),
+            _inspector: inspector.name(),
+            _timeline: timeline.name(),
+            _profiler: profiler.name(),
+            _performance: performance.name(),
+            _styleSheets: styleSheets.name(),
+            _tab: tabdesc.name(),
             thread: thread.name(),
             streams: RefCell::new(HashMap::new()),
             browsing_context_id: id,

components/media/media_channel/mpsc.rs

@@ -6,7 +6,6 @@ use serde::{Deserialize, Serialize};
 use serde::{Deserializer, Serializer};
 use std::sync::mpsc;
 
-#[macro_use]
 macro_rules! unreachable_serializable {
     ($name:ident) => {
         impl<T> Serialize for $name<T> {

components/net/http_cache.rs

@@ -230,8 +230,8 @@ fn get_response_expiry(response: &Response) -> Duration {
         let max_heuristic = Duration::hours(24) - age;
         let heuristic_freshness = if let Some(last_modified) =
             // If the response has a Last-Modified header field,
-        // caches are encouraged to use a heuristic expiration value
-        // that is no more than some fraction of the interval since that time.
+            // caches are encouraged to use a heuristic expiration value
+            // that is no more than some fraction of the interval since that time.
             response.headers.typed_get::<LastModified>()
         {
             let current = time::now().to_timespec();

components/script/lib.rs

@@ -2,9 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-#![feature(assoc_char_funcs)]
-#![feature(const_fn)]
 #![feature(const_fn_fn_ptr_basics)]
+#![feature(const_fn_trait_bound)]
 #![feature(core_intrinsics)]
 #![feature(drain_filter)]
 #![feature(plugin)]

components/script_plugins/lib.rs

@@ -405,7 +405,10 @@ fn match_def_path(cx: &LateContext, def_id: DefId, path: &[Symbol]) -> bool {
 fn in_derive_expn(span: Span) -> bool {
     matches!(
         span.ctxt().outer_expn_data().kind,
-        ExpnKind::Macro(MacroKind::Derive, _)
+        ExpnKind::Macro {
+            kind: MacroKind::Derive,
+            ..
+        }
     )
 }
 

rust-toolchain

@@ -1 +1 @@
-nightly-2021-03-12
+nightly-2021-05-18