Flag, but don't fix, unused imports in ModuleNotFoundError blocks (#3658)

crates/ruff_python_ast/src/context.rs

@@ -8,10 +8,10 @@ use smallvec::smallvec;
 use ruff_python_stdlib::path::is_python_stub_file;
 use ruff_python_stdlib::typing::TYPING_EXTENSIONS;
 
-use crate::helpers::{collect_call_path, from_relative_import, Exceptions};
+use crate::helpers::{collect_call_path, from_relative_import};
 use crate::scope::{
-    Binding, BindingId, BindingKind, Bindings, ExecutionContext, Scope, ScopeId, ScopeKind,
-    ScopeStack, Scopes,
+    Binding, BindingId, BindingKind, Bindings, Exceptions, ExecutionContext, Scope, ScopeId,
+    ScopeKind, ScopeStack, Scopes,
 };
 use crate::types::{CallPath, RefEquality};
 use crate::typing::AnnotationKind;
@@ -309,6 +309,7 @@ impl<'a> Context<'a> {
         self.in_exception_handler
     }
 
+    /// Return the [`ExecutionContext`] of the current scope.
     pub const fn execution_context(&self) -> ExecutionContext {
         if self.in_type_checking_block
             || self.in_annotation
@@ -319,4 +320,13 @@ impl<'a> Context<'a> {
             ExecutionContext::Runtime
         }
     }
+
+    /// Return the union of all handled exceptions as an [`Exceptions`] bitflag.
+    pub fn exceptions(&self) -> Exceptions {
+        let mut exceptions = Exceptions::empty();
+        for exception in &self.handled_exceptions {
+            exceptions.insert(*exception);
+        }
+        exceptions
+    }
 }

crates/ruff_python_ast/src/helpers.rs

@@ -1,6 +1,5 @@
 use std::path::Path;
 
-use bitflags::bitflags;
 use itertools::Itertools;
 use log::error;
 use once_cell::sync::Lazy;
@@ -577,13 +576,6 @@ pub fn has_non_none_keyword(keywords: &[Keyword], keyword: &str) -> bool {
     })
 }
 
-bitflags! {
-    pub struct Exceptions: u32 {
-        const NAME_ERROR = 0b0000_0001;
-        const MODULE_NOT_FOUND_ERROR = 0b0000_0010;
-    }
-}
-
 /// Extract the names of all handled exceptions.
 pub fn extract_handled_exceptions(handlers: &[Excepthandler]) -> Vec<&Expr> {
     let mut handled_exceptions = Vec::new();

crates/ruff_python_ast/src/scope.rs

@@ -1,4 +1,5 @@
 use crate::types::{Range, RefEquality};
+use bitflags::bitflags;
 use rustc_hash::FxHashMap;
 use rustpython_parser::ast::{Arguments, Expr, Keyword, Stmt};
 use std::num::TryFromIntError;
@@ -222,6 +223,14 @@ impl Default for ScopeStack {
     }
 }
 
+bitflags! {
+    pub struct Exceptions: u32 {
+        const NAME_ERROR = 0b0000_0001;
+        const MODULE_NOT_FOUND_ERROR = 0b0000_0010;
+        const IMPORT_ERROR = 0b0000_0100;
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct Binding<'a> {
     pub kind: BindingKind<'a>,
@@ -241,6 +250,8 @@ pub struct Binding<'a> {
     /// (e.g.) `__future__` imports, explicit re-exports, and other bindings
     /// that should be considered used even if they're never referenced.
     pub synthetic_usage: Option<(ScopeId, Range)>,
+    /// The exceptions that were handled when the binding was defined.
+    pub exceptions: Exceptions,
 }
 
 impl<'a> Binding<'a> {