No tracing of nop traceable fields (#29926)

* Add `no_trace` option to JSTraceable derive

* NoTrace wrapper

* Port some types to no_trace schematics

* Fixing my unsafe mistakes (not tracing traceables)

* Add docs & safety guards for no_trace

Safety guards (trait shenanigans) guarantees safety usage of `no_trace`

* Port canvas_traits to no_trace

* Port servo_media to no_trace

* Port net_traits to no_trace

* Port style to no_trace

* Port webgpu to no_trace

* Port script_traits to no_trace

* Port canvas_traits, devtools_traits, embedder_traits, profile_traits to no_trace

* unrooted_must_root lint in seperate file

* Add trace_in_no_trace_lint as script_plugin

* Composable types in must_not_have_traceable

* Introduced HashMapTracedValues wrapper

* `HashMap<NoTrace<K>,V>`->`HashMapTracedValues<K,V>`

* Port rest of servo's types to no_trace

* Port html5ever, euclid, mime and http to no_trace

* Port remaining externals to no_trace

* Port webxr and Arc<Mutex<_>>

* Fix spelling in notrace doc

components/script/dom/servoparser/async_html.rs

@@ -43,6 +43,7 @@ type ParseNodeId = usize;
 #[derive(Clone, JSTraceable, MallocSizeOf)]
 pub struct ParseNode {
     id: ParseNodeId,
+    #[no_trace]
     qual_name: Option<QualName>,
 }
 
@@ -54,6 +55,7 @@ enum NodeOrText {
 
 #[derive(JSTraceable, MallocSizeOf)]
 struct Attribute {
+    #[no_trace]
     name: QualName,
     value: String,
 }
@@ -67,6 +69,7 @@ enum ParseOperation {
 
     CreateElement {
         node: ParseNodeId,
+        #[no_trace]
         name: QualName,
         attrs: Vec<Attribute>,
         current_line: u64,
@@ -130,6 +133,7 @@ enum ParseOperation {
 
     SetQuirksMode {
         #[ignore_malloc_size_of = "Defined in style"]
+        #[no_trace]
         mode: ServoQuirksMode,
     },
 }
@@ -200,11 +204,14 @@ fn create_buffer_queue(mut buffers: VecDeque<SendTendril<UTF8>>) -> BufferQueue
 pub struct Tokenizer {
     document: Dom<Document>,
     #[ignore_malloc_size_of = "Defined in std"]
+    #[no_trace]
     receiver: Receiver<ToTokenizerMsg>,
     #[ignore_malloc_size_of = "Defined in std"]
+    #[no_trace]
     html_tokenizer_sender: Sender<ToHtmlTokenizerMsg>,
     #[ignore_malloc_size_of = "Defined in std"]
     nodes: HashMap<ParseNodeId, Dom<Node>>,
+    #[no_trace]
     url: ServoUrl,
     parsing_algorithm: ParsingAlgorithm,
 }

components/script/dom/servoparser/mod.rs

@@ -95,9 +95,11 @@ pub struct ServoParser {
     network_decoder: DomRefCell<Option<NetworkDecoder>>,
     /// Input received from network.
     #[ignore_malloc_size_of = "Defined in html5ever"]
+    #[no_trace]
     network_input: DomRefCell<BufferQueue>,
     /// Input received from script. Used only to support document.write().
     #[ignore_malloc_size_of = "Defined in html5ever"]
+    #[no_trace]
     script_input: DomRefCell<BufferQueue>,
     /// The tokenizer of this parser.
     tokenizer: DomRefCell<Tokenizer>,
@@ -116,6 +118,7 @@ pub struct ServoParser {
     // building the DOM. https://github.com/servo/servo/pull/19203
     prefetch_tokenizer: DomRefCell<prefetch::Tokenizer>,
     #[ignore_malloc_size_of = "Defined in html5ever"]
+    #[no_trace]
     prefetch_input: DomRefCell<BufferQueue>,
 }
 
@@ -1046,6 +1049,7 @@ fn insert(
 #[derive(JSTraceable, MallocSizeOf)]
 #[unrooted_must_root_lint::must_root]
 pub struct Sink {
+    #[no_trace]
     base_url: ServoUrl,
     document: Dom<Document>,
     current_line: u64,
@@ -1401,6 +1405,7 @@ impl NetworkDecoder {
 
 #[derive(Default, JSTraceable)]
 struct NetworkSink {
+    #[no_trace]
     output: StrTendril,
 }
 

components/script/dom/servoparser/prefetch.rs

@@ -75,12 +75,19 @@ impl Tokenizer {
 
 #[derive(JSTraceable)]
 struct PrefetchSink {
+    #[no_trace]
     origin: ImmutableOrigin,
+    #[no_trace]
     pipeline_id: PipelineId,
+    #[no_trace]
     document_url: ServoUrl,
+    #[no_trace]
     base_url: Option<ServoUrl>,
+    #[no_trace]
     referrer: Referrer,
+    #[no_trace]
     referrer_policy: Option<ReferrerPolicy>,
+    #[no_trace]
     resource_threads: ResourceThreads,
     prefetching: bool,
 }