fix equal checks for cells and output (#8721)

### Description

* Check for equal Vc on returning a value
* Avoid PartialEq checks for values that are never equal

### Testing Instructions

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  Give a quick description of steps to test your changes.
-->

crates/turbo-tasks-memory/src/output.rs

@@ -56,7 +56,17 @@ impl Output {
 
  pub fn link(&mut self, target: RawVc, turbo_tasks: &dyn TurboTasksBackendApi<MemoryBackend>) {
  debug_assert!(*self != target);
- self.assign(OutputContent::Link(target), turbo_tasks)
+ if let OutputContent::Link(old_target) = &self.content {
+ if *old_target == target {
+ // unchanged
+ return;
+ }
+ }
+ self.content = OutputContent::Link(target);
+ // notify
+ if !self.dependent_tasks.is_empty() {
+ turbo_tasks.schedule_notify_tasks_set(&take(&mut self.dependent_tasks));
+ }
  }
 
  pub fn error(&mut self, error: Error, turbo_tasks: &dyn TurboTasksBackendApi<MemoryBackend>) {
@@ -79,18 +89,6 @@ impl Output {
  }
  }
 
- pub fn assign(
- &mut self,
- content: OutputContent,
- turbo_tasks: &dyn TurboTasksBackendApi<MemoryBackend>,
- ) {
- self.content = content;
- // notify
- if !self.dependent_tasks.is_empty() {
- turbo_tasks.schedule_notify_tasks_set(&take(&mut self.dependent_tasks));
- }
- }
-
  pub fn gc_drop(self, turbo_tasks: &dyn TurboTasksBackendApi<MemoryBackend>) {
  // notify
  if !self.dependent_tasks.is_empty() {

crates/turbopack-core/src/source_map/mod.rs

@@ -43,7 +43,7 @@ pub trait GenerateSourceMap {
 /// The distinction between the source map spec's [sourcemap::Index] and our
 /// [SourceMap::Sectioned] is whether the sections are represented with Vcs
 /// pointers.
-#[turbo_tasks::value(shared)]
+#[turbo_tasks::value(shared, cell = "new")]
 pub enum SourceMap {
  /// A decoded source map contains no Vcs.
  Decoded(#[turbo_tasks(trace_ignore)] InnerSourceMap),

crates/turbopack-css/src/process.rs

@@ -274,7 +274,7 @@ impl<'i, 'o> StyleSheetLike<'i, 'o> {
 #[turbo_tasks::value(transparent)]
 pub struct UnresolvedUrlReferences(pub Vec<(String, Vc<UrlAssetReference>)>);
 
-#[turbo_tasks::value(shared, serialization = "none", eq = "manual")]
+#[turbo_tasks::value(shared, serialization = "none", eq = "manual", cell = "new")]
 pub enum ParseCssResult {
  Ok {
  #[turbo_tasks(debug_ignore, trace_ignore)]
@@ -296,13 +296,7 @@ pub enum ParseCssResult {
  NotFound,
 }
 
-impl PartialEq for ParseCssResult {
- fn eq(&self, _: &Self) -> bool {
- false
- }
-}
-
-#[turbo_tasks::value(shared, serialization = "none", eq = "manual")]
+#[turbo_tasks::value(shared, serialization = "none", eq = "manual", cell = "new")]
 pub enum CssWithPlaceholderResult {
  Ok {
  parse_result: Vc<ParseCssResult>,
@@ -324,12 +318,6 @@ pub enum CssWithPlaceholderResult {
  NotFound,
 }
 
-impl PartialEq for CssWithPlaceholderResult {
- fn eq(&self, _: &Self) -> bool {
- false
- }
-}
-
 #[turbo_tasks::value(shared, serialization = "none", eq = "manual")]
 pub enum FinalCssResult {
  Ok {
@@ -390,10 +378,10 @@ pub async fn process_css_with_placeholder(
  url_references: *url_references,
  placeholders: HashMap::new(),
  }
- .into())
+ .cell())
  }
- ParseCssResult::Unparseable => Ok(CssWithPlaceholderResult::Unparseable.into()),
- ParseCssResult::NotFound => Ok(CssWithPlaceholderResult::NotFound.into()),
+ ParseCssResult::Unparseable => Ok(CssWithPlaceholderResult::Unparseable.cell()),
+ ParseCssResult::NotFound => Ok(CssWithPlaceholderResult::NotFound.cell()),
  }
 }
 
@@ -602,7 +590,7 @@ async fn process_content(
  }
  .cell()
  .emit();
- return Ok(ParseCssResult::Unparseable.into());
+ return Ok(ParseCssResult::Unparseable.cell());
  }
 
  _ => {
@@ -629,7 +617,7 @@ async fn process_content(
  }
  .cell()
  .emit();
- return Ok(ParseCssResult::Unparseable.into());
+ return Ok(ParseCssResult::Unparseable.cell());
  }
  }
  })
@@ -669,12 +657,12 @@ async fn process_content(
  Ok(v) => v,
  Err(err) => {
  err.to_diagnostics(&handler).emit();
- return Ok(ParseCssResult::Unparseable.into());
+ return Ok(ParseCssResult::Unparseable.cell());
  }
  };
 
  if handler.has_errors() {
- return Ok(ParseCssResult::Unparseable.into());
+ return Ok(ParseCssResult::Unparseable.cell());
  }
 
  if matches!(ty, CssModuleAssetType::Module) {
@@ -722,7 +710,7 @@ async fn process_content(
  url_references: Vc::cell(url_references),
  options: config,
  }
- .into())
+ .cell())
 }
 
 /// Visitor that lints wrong css module usage.