Improve detection of TYPE_CHECKING blocks imported from typing_extensions or _typeshed (#8429)

~Improves detection of types imported from `typing_extensions`. Removes
the hard-coded list of supported types in `typing_extensions`; instead
assuming all types could be imported from `typing`, `_typeshed`, or
`typing_extensions`.~

~The typing extensions package appears to re-export types even if they
do not need modification.~


Adds detection of `if typing_extensions.TYPE_CHECKING` blocks. Avoids
inserting a new `if TYPE_CHECKING` block and `from typing import
TYPE_CHECKING` if `typing_extensions.TYPE_CHECKING` is used (closes
https://github.com/astral-sh/ruff/issues/8427)

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/ruff_python_semantic/src/analyze/typing.rs

@@ -315,10 +315,7 @@ pub fn is_type_checking_block(stmt: &ast::StmtIf, semantic: &SemanticModel) -> b
     }
 
     // Ex) `if typing.TYPE_CHECKING:`
-    if semantic
-        .resolve_call_path(test)
-        .is_some_and(|call_path| matches!(call_path.as_slice(), ["typing", "TYPE_CHECKING"]))
-    {
+    if semantic.match_typing_expr(test, "TYPE_CHECKING") {
         return true;
     }
 

crates/ruff_python_semantic/src/model.rs

@@ -200,6 +200,14 @@ impl<'a> SemanticModel<'a> {
         false
     }
 
+    /// Return an iterator over the set of `typing` modules allowed in the semantic model.
+    pub fn typing_modules(&self) -> impl Iterator<Item = &str> {
+        ["typing", "_typeshed", "typing_extensions"]
+            .iter()
+            .copied()
+            .chain(self.typing_modules.iter().map(String::as_str))
+    }
+
     /// Create a new [`Binding`] for a builtin.
     pub fn push_builtin(&mut self) -> BindingId {
         self.bindings.push(Binding {