Add tests for hard and soft links (#12590)

clippy.toml

@@ -10,12 +10,12 @@ doc-valid-idents = [
   "SCREAMING_SNAKE_CASE",
   "SQLAlchemy",
   "StackOverflow",
+  "PyCharm",
 ]
 
 ignore-interior-mutability = [
   # Interned is read-only. The wrapped `Rc` never gets updated.
   "ruff_formatter::format_element::Interned",
-
-  # The expression is read-only. 
+  # The expression is read-only.
   "ruff_python_ast::hashable::HashableExpr",
 ]

crates/red_knot/Cargo.toml

@@ -27,12 +27,12 @@ notify = { workspace = true }
 rayon = { workspace = true }
 rustc-hash = { workspace = true }
 salsa = { workspace = true }
-filetime = { workspace = true }
 tracing = { workspace = true }
 tracing-subscriber = { workspace = true }
 tracing-tree = { workspace = true }
 
 [dev-dependencies]
+filetime = { workspace = true }
 tempfile = { workspace = true }
 
 

crates/red_knot/src/db.rs

@@ -1,7 +1,4 @@
 use std::panic::{AssertUnwindSafe, RefUnwindSafe};
-use std::sync::Arc;
-
-use salsa::Cancelled;
 
 use red_knot_module_resolver::{vendored_typeshed_stubs, Db as ResolverDb};
 use red_knot_python_semantic::Db as SemanticDb;
@@ -10,6 +7,7 @@ use ruff_db::program::{Program, ProgramSettings};
 use ruff_db::system::System;
 use ruff_db::vendored::VendoredFileSystem;
 use ruff_db::{Db as SourceDb, Upcast};
+use salsa::Cancelled;
 
 use crate::lint::Diagnostics;
 use crate::workspace::{check_file, Workspace, WorkspaceMetadata};
@@ -24,7 +22,7 @@ pub struct RootDatabase {
     workspace: Option<Workspace>,
     storage: salsa::Storage<RootDatabase>,
     files: Files,
-    system: Arc<dyn System + Send + Sync + RefUnwindSafe>,
+    system: Box<dyn System + Send + Sync + RefUnwindSafe>,
 }
 
 impl RootDatabase {
@@ -36,7 +34,7 @@ impl RootDatabase {
             workspace: None,
             storage: salsa::Storage::default(),
             files: Files::default(),
-            system: Arc::new(system),
+            system: Box::new(system),
         };
 
         let workspace = Workspace::from_metadata(&db, workspace);