Improve reference resolution for deferred-annotations-within-classes (#4509)

crates/ruff/resources/test/fixtures/pyflakes/F401_12.py

@@ -0,0 +1,10 @@
+"""Test: module bindings are preferred over local bindings, for deferred annotations."""
+
+from __future__ import annotations
+
+import datetime
+from typing import Optional
+
+
+class Class:
+    datetime: Optional[datetime.datetime]

crates/ruff/resources/test/fixtures/pyflakes/F401_13.py

@@ -0,0 +1,12 @@
+"""Test: module bindings are preferred over local bindings, for deferred annotations."""
+
+from __future__ import annotations
+
+from typing import TypeAlias, List
+
+
+class Class:
+    List: TypeAlias = List
+
+    def bar(self) -> List:
+        pass

crates/ruff/resources/test/fixtures/pyflakes/F401_14.py

@@ -0,0 +1,8 @@
+"""Test: module bindings are preferred over local bindings, for deferred annotations."""
+
+import datetime
+from typing import Optional
+
+
+class Class:
+    datetime: "Optional[datetime.datetime]"

crates/ruff/src/rules/pyflakes/mod.rs

@@ -36,6 +36,9 @@ mod tests {
     #[test_case(Rule::UnusedImport, Path::new("F401_9.py"); "F401_9")]
     #[test_case(Rule::UnusedImport, Path::new("F401_10.py"); "F401_10")]
     #[test_case(Rule::UnusedImport, Path::new("F401_11.py"); "F401_11")]
+    #[test_case(Rule::UnusedImport, Path::new("F401_12.py"); "F401_12")]
+    #[test_case(Rule::UnusedImport, Path::new("F401_13.py"); "F401_13")]
+    #[test_case(Rule::UnusedImport, Path::new("F401_14.py"); "F401_14")]
     #[test_case(Rule::ImportShadowedByLoopVar, Path::new("F402.py"); "F402")]
     #[test_case(Rule::UndefinedLocalWithImportStar, Path::new("F403.py"); "F403")]
     #[test_case(Rule::LateFutureImport, Path::new("F404.py"); "F404")]

crates/ruff/src/rules/pyflakes/snapshots/ruff__rules__pyflakes__tests__F401_F401_12.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff/src/rules/pyflakes/mod.rs
+---
+

crates/ruff/src/rules/pyflakes/snapshots/ruff__rules__pyflakes__tests__F401_F401_13.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff/src/rules/pyflakes/mod.rs
+---
+

crates/ruff/src/rules/pyflakes/snapshots/ruff__rules__pyflakes__tests__F401_F401_14.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff/src/rules/pyflakes/mod.rs
+---
+

crates/ruff_python_semantic/src/context.rs

@@ -116,6 +116,16 @@ impl<'a> Context<'a> {
 
     /// Resolve a reference to the given symbol.
     pub fn resolve_reference(&mut self, symbol: &str, range: TextRange) -> ResolvedReference {
+        // PEP 563 indicates that if a forward reference can be resolved in the module scope, we
+        // should prefer it over local resolutions.
+        if self.in_deferred_type_definition() {
+            if let Some(binding_id) = self.scopes.global().get(symbol) {
+                let context = self.execution_context();
+                self.bindings[*binding_id].mark_used(ScopeId::global(), range, context);
+                return ResolvedReference::Resolved(ScopeId::global(), *binding_id);
+            }
+        }
+
         let mut import_starred = false;
         for (index, scope_id) in self.scopes.ancestor_ids(self.scope_id).enumerate() {
             let scope = &self.scopes[scope_id];
@@ -750,7 +760,7 @@ impl ContextFlags {
 }
 
 /// A snapshot of the [`Context`] at a given point in the AST traversal.
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct Snapshot {
     scope_id: ScopeId,
     stmt_id: Option<NodeId>,