Fix warnings introduced in newer Rust Nightly

This does not (yet) upgrade ./rust-toolchain

The warnings:

* dead_code "field is never read"
* redundant_semicolons "unnecessary trailing semicolon"
* non_fmt_panic "panic message is not a string literal, this is no longer accepted in Rust 2021"
* unstable_name_collisions "a method with this name may be added to the standard library in the future"
* legacy_derive_helpers "derive helper attribute is used before it is introduced" rust-lang/rust#79202

components/compositing/build.rs

@@ -47,6 +47,6 @@ fn main() {
                 _ => panic!("Cannot find package definitions in lockfile"),
             }
         },
-        Err(e) => panic!(e),
+        Err(e) => panic!("{}", e),
     }
 }

components/compositing/compositor.rs

@@ -141,9 +141,6 @@ pub struct IOCompositor<Window: WindowMethods + ?Sized> {
     /// the compositor.
     pub shutdown_state: ShutdownState,
 
-    /// Tracks the last composite time.
-    last_composite_time: u64,
-
     /// Tracks whether the zoom action has happened recently.
     zoom_action: bool,
 
@@ -320,7 +317,6 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
             frame_tree_id: FrameTreeId(0),
             constellation_chan: state.constellation_chan,
             time_profiler_chan: state.time_profiler_chan,
-            last_composite_time: 0,
             ready_to_save_state: ReadyState::Unknown,
             webrender: state.webrender,
             webrender_document: state.webrender_document,
@@ -1580,8 +1576,6 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
             warn!("Failed to present surface: {:?}", err);
         }
 
-        self.last_composite_time = precise_time_ns();
-
         self.composition_request = CompositionRequest::NoCompositingNecessary;
 
         self.process_animations();

components/config/pref_util.rs

@@ -113,12 +113,7 @@ macro_rules! impl_from_pref {
                     if let $variant(value) = other {
                         value.into()
                     } else {
-                        panic!(
-                            format!("Cannot convert {:?} to {:?}",
-                                other,
-                                std::any::type_name::<$t>()
-                            )
-                        );
+                        panic!("Cannot convert {:?} to {:?}", other, std::any::type_name::<$t>())
                     }
                 }
             }

components/config_plugins/lib.rs

@@ -132,12 +132,14 @@ impl Build {
             .get_field_name_mapping()
             .map(|pref_attr| pref_attr.value())
             .unwrap_or_else(|| {
-                path_stack
-                    .iter()
-                    .chain(iter::once(&field.name))
-                    .map(Ident::to_string)
-                    .intersperse(String::from("."))
-                    .collect()
+                Itertools::intersperse(
+                    path_stack
+                        .iter()
+                        .chain(iter::once(&field.name))
+                        .map(Ident::to_string),
+                    String::from("."),
+                )
+                .collect()
             })
     }
 

components/devtools/actors/framerate.rs

@@ -11,13 +11,12 @@ use msg::constellation_msg::PipelineId;
 use serde_json::{Map, Value};
 use std::mem;
 use std::net::TcpStream;
-use time::precise_time_ns;
 
 pub struct FramerateActor {
     name: String,
     pipeline: PipelineId,
     script_sender: IpcSender<DevtoolScriptControlMsg>,
-    start_time: Option<u64>,
+
     is_recording: bool,
     ticks: Vec<HighResolutionStamp>,
 }
@@ -51,7 +50,6 @@ impl FramerateActor {
             name: actor_name.clone(),
             pipeline: pipeline_id,
             script_sender: script_sender,
-            start_time: None,
             is_recording: false,
             ticks: Vec::new(),
         };
@@ -79,7 +77,6 @@ impl FramerateActor {
             return;
         }
 
-        self.start_time = Some(precise_time_ns());
         self.is_recording = true;
 
         let msg = DevtoolScriptControlMsg::RequestAnimationFrame(self.pipeline, self.name());
@@ -91,7 +88,6 @@ impl FramerateActor {
             return;
         }
         self.is_recording = false;
-        self.start_time = None;
     }
 }
 

components/layout/table_wrapper.rs

@@ -157,7 +157,7 @@ impl TableWrapperFlow {
             .zip(guesses.iter())
         {
             intermediate_column_inline_size.size = guess.calculate(selection);
-            intermediate_column_inline_size.percentage = 0.0;
+            // intermediate_column_inline_size.percentage = 0.0;
             total_used_inline_size = total_used_inline_size + intermediate_column_inline_size.size
         }
 
@@ -382,7 +382,7 @@ impl Flow for TableWrapperFlow {
             .map(
                 |column_intrinsic_inline_size| IntermediateColumnInlineSize {
                     size: column_intrinsic_inline_size.minimum_length,
-                    percentage: column_intrinsic_inline_size.percentage,
+                    // percentage: column_intrinsic_inline_size.percentage,
                 },
             )
             .collect::<Vec<_>>();
@@ -822,7 +822,9 @@ impl ExcessInlineSizeDistributionInfo {
 /// An intermediate column size assignment.
 struct IntermediateColumnInlineSize {
     size: Au,
-    percentage: f32,
+    // This used to be stored here but nothing used it,
+    // which started emitting a compiler warning: https://github.com/servo/servo/pull/28202
+    // percentage: f32,
 }
 
 /// Returns the computed inline size of the table wrapper represented by `block`.

components/layout_thread/lib.rs

@@ -189,9 +189,6 @@ pub struct LayoutThread {
     /// The root of the flow tree.
     root_flow: RefCell<Option<FlowRef>>,
 
-    /// The document-specific shared lock used for author-origin stylesheets
-    document_shared_lock: Option<SharedRwLock>,
-
     /// A counter for epoch messages
     epoch: Cell<Epoch>,
 
@@ -543,7 +540,6 @@ impl LayoutThread {
             generation: Cell::new(0),
             outstanding_web_fonts: Arc::new(AtomicUsize::new(0)),
             root_flow: RefCell::new(None),
-            document_shared_lock: None,
             // Epoch starts at 1 because of the initial display list for epoch 0 that we send to WR
             epoch: Cell::new(Epoch(1)),
             viewport_size: Size2D::new(Au(0), Au(0)),
@@ -1261,7 +1257,6 @@ impl LayoutThread {
         // Calculate the actual viewport as per DEVICE-ADAPT § 6
         // If the entire flow tree is invalid, then it will be reflowed anyhow.
         let document_shared_lock = document.style_shared_lock();
-        self.document_shared_lock = Some(document_shared_lock.clone());
         let author_guard = document_shared_lock.read();
 
         let ua_stylesheets = &*UA_STYLESHEETS;

components/layout_thread_2020/lib.rs

@@ -167,9 +167,6 @@ pub struct LayoutThread {
     /// The fragment tree.
     fragment_tree: RefCell<Option<Arc<FragmentTree>>>,
 
-    /// The document-specific shared lock used for author-origin stylesheets
-    document_shared_lock: Option<SharedRwLock>,
-
     /// A counter for epoch messages
     epoch: Cell<Epoch>,
 
@@ -510,7 +507,6 @@ impl LayoutThread {
             outstanding_web_fonts: Arc::new(AtomicUsize::new(0)),
             box_tree: Default::default(),
             fragment_tree: Default::default(),
-            document_shared_lock: None,
             // Epoch starts at 1 because of the initial display list for epoch 0 that we send to WR
             epoch: Cell::new(Epoch(1)),
             viewport_size: Size2D::new(Au(0), Au(0)),
@@ -947,7 +943,6 @@ impl LayoutThread {
         // Calculate the actual viewport as per DEVICE-ADAPT § 6
         // If the entire flow tree is invalid, then it will be reflowed anyhow.
         let document_shared_lock = document.style_shared_lock();
-        self.document_shared_lock = Some(document_shared_lock.clone());
         let author_guard = document_shared_lock.read();
 
         let ua_stylesheets = &*UA_STYLESHEETS;

components/net/tests/data_loader.rs

@@ -44,7 +44,7 @@ fn assert_parse(
                     filtered: FilteredMetadata::Basic(m),
                     ..
                 }) => m,
-                result => panic!(result),
+                result => panic!("{:?}", result),
             };
             assert_eq!(metadata.content_type.map(Serde::into_inner), content_type);
             assert_eq!(metadata.charset.as_ref().map(String::deref), charset);

components/net_traits/response.rs

@@ -312,7 +312,7 @@ impl Response {
             metadata.referrer_policy = response.referrer_policy.clone();
             metadata.redirected = response.actual_response().url_list.len() > 1;
             metadata
-        };
+        }
 
         if let Some(error) = self.get_network_error() {
             return Err(error.clone());

components/profile/mem.rs

@@ -101,18 +101,15 @@ impl Profiler {
                 let name_clone = name.clone();
                 match self.reporters.insert(name, reporter) {
                     None => true,
-                    Some(_) => panic!(format!(
-                        "RegisterReporter: '{}' name is already in use",
-                        name_clone
-                    )),
+                    Some(_) => panic!("RegisterReporter: '{}' name is already in use", name_clone),
                 }
             },
 
             ProfilerMsg::UnregisterReporter(name) => {
                 // Panic if it hasn't previously been registered.
                 match self.reporters.remove(&name) {
                     Some(_) => true,
-                    None => panic!(format!("UnregisterReporter: '{}' name is unknown", &name)),
+                    None => panic!("UnregisterReporter: '{}' name is unknown", &name),
                 }
             },
 

components/style/gecko/url.rs

@@ -21,8 +21,8 @@ use style_traits::{CssWriter, ParseError, ToCss};
 use to_shmem::{self, SharedMemoryBuilder, ToShmem};
 
 /// A CSS url() value for gecko.
-#[css(function = "url")]
 #[derive(Clone, Debug, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
+#[css(function = "url")]
 #[repr(C)]
 pub struct CssUrl(pub Arc<CssUrlData>);
 

components/style/media_queries/media_list.rs

@@ -14,8 +14,8 @@ use cssparser::{Delimiter, Parser};
 use cssparser::{ParserInput, Token};
 
 /// A type that encapsulates a media query list.
-#[css(comma, derive_debug)]
 #[derive(Clone, MallocSizeOf, ToCss, ToShmem)]
+#[css(comma, derive_debug)]
 pub struct MediaList {
     /// The list of media queries.
     #[css(iterable)]

components/style/properties/helpers.mako.rs

@@ -170,9 +170,6 @@
             /// Making this type generic allows the compiler to figure out the
             /// animated value for us, instead of having to implement it
             /// manually for every type we care about.
-            % if separator == "Comma":
-            #[css(comma)]
-            % endif
             #[derive(
                 Clone,
                 Debug,
@@ -182,6 +179,9 @@
                 ToResolvedValue,
                 ToCss,
             )]
+            % if separator == "Comma":
+            #[css(comma)]
+            % endif
             pub struct OwnedList<T>(
                 % if not allow_empty:
                 #[css(iterable)]
@@ -198,16 +198,16 @@
             % else:
             pub use self::ComputedList as List;
 
-            % if separator == "Comma":
-            #[css(comma)]
-            % endif
             #[derive(
                 Clone,
                 Debug,
                 MallocSizeOf,
                 PartialEq,
                 ToCss,
             )]
+            % if separator == "Comma":
+            #[css(comma)]
+            % endif
             pub struct ComputedList(
                 % if not allow_empty:
                 #[css(iterable)]
@@ -324,10 +324,10 @@
         }
 
         /// The specified value of ${name}.
+        #[derive(Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
         % if separator == "Comma":
         #[css(comma)]
         % endif
-        #[derive(Clone, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
         pub struct SpecifiedValue(
             % if not allow_empty:
             #[css(iterable)]

components/style/stylesheets/document_rule.rs

@@ -215,8 +215,8 @@ impl DocumentMatchingFunction {
 /// The `@document` rule's condition is written as a comma-separated list of
 /// URL matching functions, and the condition evaluates to true whenever any
 /// one of those functions evaluates to true.
-#[css(comma)]
 #[derive(Clone, Debug, ToCss, ToShmem)]
+#[css(comma)]
 pub struct DocumentCondition(#[css(iterable)] Vec<DocumentMatchingFunction>);
 
 impl DocumentCondition {

components/style/stylesheets/keyframes_rule.rs

@@ -149,8 +149,8 @@ impl KeyframePercentage {
 
 /// A keyframes selector is a list of percentages or from/to symbols, which are
 /// converted at parse time to percentages.
-#[css(comma)]
 #[derive(Clone, Debug, Eq, PartialEq, ToCss, ToShmem)]
+#[css(comma)]
 pub struct KeyframeSelector(#[css(iterable)] Vec<KeyframePercentage>);
 
 impl KeyframeSelector {

components/style/values/animated/font.rs

@@ -116,7 +116,7 @@ impl<'a> FontSettingTagIter<'a> {
             let mut sorted_tags = Vec::from_iter(tags.iter());
             sorted_tags.sort_by_key(|k| k.tag.0);
             sorted_tags
-        };
+        }
 
         Ok(FontSettingTagIter {
             a_state: FontSettingTagIterState::new(as_new_sorted_tags(&a_settings.0)),