Evaluate default parameter value in enclosing scope

crates/ruff_linter/resources/test/fixtures/pyflakes/F821_17.py

@@ -111,3 +111,7 @@ def bar(x: T) -> T:  # OK
         return x
 
     bar(t)
+
+
+def cannot_access_in_default[T](t: T = T):  # F821
+    pass

crates/ruff_linter/src/checkers/ast/mod.rs

@@ -691,6 +691,14 @@ impl<'a> Visitor<'a> for Checker<'a> {
                         self.semantic(),
                     );
 
+                // The default values of the parameters needs to be evaluated in the enclosing
+                // scope.
+                for parameter in &**parameters {
+                    if let Some(expr) = parameter.default() {
+                        self.visit_expr(expr);
+                    }
+                }
+
                 self.semantic.push_scope(ScopeKind::Type);
 
                 if let Some(type_params) = type_params {
@@ -715,9 +723,6 @@ impl<'a> Visitor<'a> for Checker<'a> {
                             }
                         }
                     }
-                    if let Some(expr) = parameter.default() {
-                        self.visit_expr(expr);
-                    }
                 }
                 if let Some(expr) = returns {
                     match annotation {

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F821_F821_17.py.snap

@@ -258,3 +258,10 @@ F821_17.py:103:17: F821 Undefined name `t`
     |                 ^ F821
 104 |                 return x
     |
+
+F821_17.py:116:40: F821 Undefined name `T`
+    |
+116 | def cannot_access_in_default[T](t: T = T):  # F821
+    |                                        ^ F821
+117 |     pass
+    |