Make symbol_by_id a salsa query

crates/red_knot_python_semantic/src/symbol.rs

@@ -35,7 +35,7 @@ impl Boundness {
 /// possibly_unbound:  Symbol::Type(Type::IntLiteral(2), Boundness::PossiblyUnbound),
 /// non_existent:      Symbol::Unbound,
 /// ```
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub(crate) enum Symbol<'db> {
     Type(Type<'db>, Boundness),
     Unbound,

crates/red_knot_python_semantic/src/types.rs

@@ -68,6 +68,7 @@ pub fn check_types(db: &dyn Db, file: File) -> TypeCheckDiagnostics {
 }
 
 /// Infer the public type of a symbol (its type as seen from outside its scope).
+#[salsa::tracked]
 fn symbol_by_id<'db>(db: &'db dyn Db, scope: ScopeId<'db>, symbol: ScopedSymbolId) -> Symbol<'db> {
     let _span = tracing::trace_span!("symbol_by_id", ?symbol).entered();