From 8a459c74283c417bd81bbbe7014c68e726076889 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Tue, 12 Sep 2023 15:46:00 -0700
Subject: [PATCH 1/2] gh-109341: Fix crash on compiling invalid AST including
 TypeAlias

---
 Lib/test/test_compile.py                      | 20 +++++++++++++++++++
 ...-09-12-15-45-49.gh-issue-109341.4V5bkm.rst |  1 +
 Python/symtable.c                             |  7 ++++++-
 3 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2023-09-12-15-45-49.gh-issue-109341.4V5bkm.rst

diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index a8a519f573e663..5e72495cef96bd 100644
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -478,6 +478,26 @@ def test_compile_ast(self):
         ast.body = [_ast.BoolOp()]
         self.assertRaises(TypeError, compile, ast, '<ast>', 'exec')
 
+    def test_compile_invalid_typealias(self):
+        # gh-109341
+        m = ast.Module(
+            body=[
+                ast.TypeAlias(
+                    name=ast.Subscript(
+                        value=ast.Name(id="foo", ctx=ast.Load()),
+                        slice=ast.Constant(value="x"),
+                        ctx=ast.Store(),
+                    ),
+                    type_params=[],
+                    value=ast.Name(id="Callable", ctx=ast.Load()),
+                )
+            ],
+            type_ignores=[],
+        )
+
+        with self.assertRaises(SyntaxError):
+            compile(ast.fix_missing_locations(m), "<file>", "exec")
+
     def test_dict_evaluation_order(self):
         i = 0
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-09-12-15-45-49.gh-issue-109341.4V5bkm.rst b/Misc/NEWS.d/next/Core and Builtins/2023-09-12-15-45-49.gh-issue-109341.4V5bkm.rst
new file mode 100644
index 00000000000000..9e99ef7eb73273
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2023-09-12-15-45-49.gh-issue-109341.4V5bkm.rst	
@@ -0,0 +1 @@
+Fix crash when compiling an invalid AST involving a :class:`ast.TypeAlias`.
diff --git a/Python/symtable.c b/Python/symtable.c
index d737c09203d31b..f474ac7fffb626 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -1581,7 +1581,12 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
     }
     case TypeAlias_kind: {
         VISIT(st, expr, s->v.TypeAlias.name);
-        assert(s->v.TypeAlias.name->kind == Name_kind);
+        // This is only possible for a manually created AST
+        if (s->v.TypeAlias.name->kind != Name_kind) {
+            PyErr_SetString(PyExc_SyntaxError,
+                            "Type alias name must be a simple name");
+            VISIT_QUIT(st, 0);
+        }
         PyObject *name = s->v.TypeAlias.name->v.Name.id;
         int is_in_class = st->st_cur->ste_type == ClassBlock;
         int is_generic = asdl_seq_LEN(s->v.TypeAlias.type_params) > 0;

From f6c10f5a4ab44461e00e0ccd93b7cf062de3e008 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Tue, 12 Sep 2023 16:09:34 -0700
Subject: [PATCH 2/2] Do it in the AST validator instead

---
 Lib/test/test_compile.py | 2 +-
 Python/ast.c             | 5 +++++
 Python/symtable.c        | 7 +------
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index 5e72495cef96bd..1beccb4b56a301 100644
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -495,7 +495,7 @@ def test_compile_invalid_typealias(self):
             type_ignores=[],
         )
 
-        with self.assertRaises(SyntaxError):
+        with self.assertRaisesRegex(TypeError, "TypeAlias with non-Name name"):
             compile(ast.fix_missing_locations(m), "<file>", "exec")
 
     def test_dict_evaluation_order(self):
diff --git a/Python/ast.c b/Python/ast.c
index 21cb38f8cbfb65..c3863d60576d37 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -768,6 +768,11 @@ validate_stmt(struct validator *state, stmt_ty stmt)
                validate_expr(state, stmt->v.AnnAssign.annotation, Load);
         break;
     case TypeAlias_kind:
+        if (stmt->v.TypeAlias.name->kind != Name_kind) {
+            PyErr_SetString(PyExc_TypeError,
+                            "TypeAlias with non-Name name");
+            return 0;
+        }
         ret = validate_expr(state, stmt->v.TypeAlias.name, Store) &&
             validate_type_params(state, stmt->v.TypeAlias.type_params) &&
             validate_expr(state, stmt->v.TypeAlias.value, Load);
diff --git a/Python/symtable.c b/Python/symtable.c
index f474ac7fffb626..d737c09203d31b 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -1581,12 +1581,7 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
     }
     case TypeAlias_kind: {
         VISIT(st, expr, s->v.TypeAlias.name);
-        // This is only possible for a manually created AST
-        if (s->v.TypeAlias.name->kind != Name_kind) {
-            PyErr_SetString(PyExc_SyntaxError,
-                            "Type alias name must be a simple name");
-            VISIT_QUIT(st, 0);
-        }
+        assert(s->v.TypeAlias.name->kind == Name_kind);
         PyObject *name = s->v.TypeAlias.name->v.Name.id;
         int is_in_class = st->st_cur->ste_type == ClassBlock;
         int is_generic = asdl_seq_LEN(s->v.TypeAlias.type_params) > 0;