[pyflakes] Skip undefined-name (F821) for conditionally deleted variables

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

@@ -1461,7 +1461,10 @@ impl<'a> Visitor<'a> for Checker<'a> {
                 }
 
                 self.semantic.set_branch(branch);
+                let flags_snapshot = self.semantic.flags;
+                self.semantic.flags |= SemanticModelFlags::ORELSE;
                 self.visit_body(orelse);
+                self.semantic.flags = flags_snapshot;
                 self.semantic.pop_branch();
 
                 self.semantic.push_branch();
@@ -1557,7 +1560,27 @@ impl<'a> Visitor<'a> for Checker<'a> {
             }) => {
                 self.visit_boolean_test(test);
                 self.visit_body(body);
+                let flags_snapshot = self.semantic.flags;
+                self.semantic.flags |= SemanticModelFlags::ORELSE;
                 self.visit_body(orelse);
+                self.semantic.flags = flags_snapshot;
+            }
+            Stmt::For(ast::StmtFor {
+                node_index: _,
+                range: _,
+                is_async: _,
+                target,
+                iter,
+                body,
+                orelse,
+            }) => {
+                self.visit_expr(iter);
+                self.visit_expr(target);
+                self.visit_body(body);
+                let flags_snapshot = self.semantic.flags;
+                self.semantic.flags |= SemanticModelFlags::ORELSE;
+                self.visit_body(orelse);
+                self.semantic.flags = flags_snapshot;
             }
             Stmt::If(
                 stmt_if @ ast::StmtIf {
@@ -1786,7 +1809,10 @@ impl<'a> Visitor<'a> for Checker<'a> {
             }) => {
                 self.visit_boolean_test(test);
                 self.visit_expr(body);
+                let flags_snapshot = self.semantic.flags;
+                self.semantic.flags |= SemanticModelFlags::ORELSE;
                 self.visit_expr(orelse);
+                self.semantic.flags = flags_snapshot;
             }
             Expr::UnaryOp(ast::ExprUnaryOp {
                 op: UnaryOp::Not,
@@ -2866,7 +2892,10 @@ impl<'a> Checker<'a> {
 
         self.semantic.resolve_del(id, expr.range());
 
-        if helpers::on_conditional_branch(&mut self.semantic.current_statements()) {
+        if helpers::on_conditional_branch(&mut self.semantic.current_statements())
+            || self.semantic.in_exception_handler()
+            || self.semantic.in_orelse()
+        {
             return;
         }
 

crates/ruff_linter/src/renamer.rs

@@ -372,7 +372,6 @@ impl Renamer {
             | BindingKind::ClassDefinition(_)
             | BindingKind::FunctionDefinition(_)
             | BindingKind::Deletion
-            | BindingKind::ConditionalDeletion(_)
             | BindingKind::UnboundException(_) => {
                 Some(Edit::range_replacement(target.to_string(), binding.range()))
             }

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

@@ -1372,6 +1372,43 @@ mod tests {
         );
     }
 
+    #[test]
+    fn del_conditional_except() {
+        // Ignores conditional bindings deletion.
+        flakes(
+            r"
+        context = None
+        test = True
+        try:
+            ...
+        except Exception:
+            del(test)
+        else:
+            assert(test)
+        ",
+            &[],
+        );
+    }
+
+    #[test]
+    fn del_conditional_orelse() {
+        // Ignores conditional bindings deletion.
+        flakes(
+            r"
+        context = None
+        test = True
+        try:
+            ...
+        except Exception:
+            print(test)
+        else:
+            del test
+        assert(test)
+        ",
+            &[],
+        );
+    }
+
     #[test]
     fn del_conditional_nested() {
         // Ignored conditional bindings deletion even if they are nested in other

crates/ruff_linter/src/rules/pylint/rules/non_ascii_name.rs

@@ -73,7 +73,6 @@ pub(crate) fn non_ascii_name(checker: &Checker, binding: &Binding) {
         | BindingKind::FromImport(_)
         | BindingKind::SubmoduleImport(_)
         | BindingKind::Deletion
-        | BindingKind::ConditionalDeletion(_)
         | BindingKind::UnboundException(_)
         | BindingKind::DunderClassCell => {
             return;

crates/ruff_linter/src/rules/ruff/rules/used_dummy_variable.rs

@@ -149,7 +149,6 @@ pub(crate) fn used_dummy_variable(checker: &Checker, binding: &Binding, binding_
         | BindingKind::FromImport(_)
         | BindingKind::SubmoduleImport(_)
         | BindingKind::Deletion
-        | BindingKind::ConditionalDeletion(_)
         | BindingKind::DunderClassCell => return,
     }
 

crates/ruff_python_semantic/src/binding.rs

@@ -230,7 +230,6 @@ impl<'a> Binding<'a> {
             // Deletions, annotations, `__future__` imports, and builtins are never considered
             // redefinitions.
             BindingKind::Deletion
-            | BindingKind::ConditionalDeletion(_)
             | BindingKind::Annotation
             | BindingKind::FutureImport
             | BindingKind::Builtin => {
@@ -642,13 +641,6 @@ pub enum BindingKind<'a> {
     /// ```
     Deletion,
 
-    /// A binding for a deletion, like `x` in:
-    /// ```python
-    /// if x > 0:
-    ///     del x
-    /// ```
-    ConditionalDeletion(BindingId),
-
     /// A binding to bind an exception to a local variable, like `x` in:
     /// ```python
     /// try:

crates/ruff_python_semantic/src/model.rs

@@ -552,15 +552,6 @@ impl<'a> SemanticModel<'a> {
                         return ReadResult::UnboundLocal(binding_id);
                     }
 
-                    BindingKind::ConditionalDeletion(binding_id) => {
-                        self.unresolved_references.push(
-                            name.range,
-                            self.exceptions(),
-                            UnresolvedReferenceFlags::empty(),
-                        );
-                        return ReadResult::UnboundLocal(binding_id);
-                    }
-
                     // If we hit an unbound exception that shadowed a bound name, resole to the
                     // bound name. For example, given:
                     //
@@ -712,7 +703,6 @@ impl<'a> SemanticModel<'a> {
                 match self.bindings[binding_id].kind {
                     BindingKind::Annotation => continue,
                     BindingKind::Deletion | BindingKind::UnboundException(None) => return None,
-                    BindingKind::ConditionalDeletion(binding_id) => return Some(binding_id),
                     BindingKind::UnboundException(Some(binding_id)) => return Some(binding_id),
                     _ => return Some(binding_id),
                 }
@@ -845,8 +835,7 @@ impl<'a> SemanticModel<'a> {
                         }
                         if let BindingKind::Annotation
                         | BindingKind::Deletion
-                        | BindingKind::UnboundException(..)
-                        | BindingKind::ConditionalDeletion(..) = binding.kind
+                        | BindingKind::UnboundException(..) = binding.kind
                         {
                             continue;
                         }
@@ -870,7 +859,6 @@ impl<'a> SemanticModel<'a> {
                     let candidate_id = match self.bindings[binding_id].kind {
                         BindingKind::Annotation => continue,
                         BindingKind::Deletion | BindingKind::UnboundException(None) => return None,
-                        BindingKind::ConditionalDeletion(binding_id) => binding_id,
                         BindingKind::UnboundException(Some(binding_id)) => binding_id,
                         _ => binding_id,
                     };
@@ -2033,6 +2021,11 @@ impl<'a> SemanticModel<'a> {
         self.flags.intersects(SemanticModelFlags::EXCEPTION_HANDLER)
     }
 
+    /// Return `true` if the model is in an exception handler.
+    pub const fn in_orelse(&self) -> bool {
+        self.flags.intersects(SemanticModelFlags::ORELSE)
+    }
+
     /// Return `true` if the model is in an `assert` statement.
     pub const fn in_assert_statement(&self) -> bool {
         self.flags.intersects(SemanticModelFlags::ASSERT_STATEMENT)
@@ -2700,6 +2693,19 @@ bitflags! {
         /// ```
         const T_STRING = 1 << 29;
 
+        /// The model is in the body of an `else` clause.
+        ///
+        /// For example, the model could be visiting `x` in:
+        /// ```python
+        /// try:
+        ///     ...
+        /// except Exception:
+        ///     ...
+        /// else:
+        ///     print(x)
+        /// ```
+        const ORELSE = 1 << 30;
+
 
         /// The context is in any type annotation.
         const ANNOTATION = Self::TYPING_ONLY_ANNOTATION.bits() | Self::RUNTIME_EVALUATED_ANNOTATION.bits() | Self::RUNTIME_REQUIRED_ANNOTATION.bits();