pythongh-130924: Do not create cells for usages of names in local annotations (python#131843)

Author: JelleZijlstra

Include/internal/pycore_symtable.h

@@ -126,6 +126,7 @@ typedef struct _symtable_entry {
     unsigned ste_method : 1; /* true if block is a function block defined in class scope */
     unsigned ste_has_conditional_annotations : 1; /* true if block has conditionally executed annotations */
     unsigned ste_in_conditional_block : 1; /* set while we are inside a conditionally executed block */
+    unsigned ste_in_unevaluated_annotation : 1; /* set while we are processing an annotation that will not be evaluated */
     int ste_comp_iter_expr; /* non-zero if visiting a comprehension range expression */
     _Py_SourceLocation ste_loc; /* source location of block */
     struct _symtable_entry *ste_annotation_block; /* symbol table entry for this entry's annotations */

Lib/test/test_type_annotations.py

@@ -3,7 +3,7 @@
 import textwrap
 import types
 import unittest
-from test.support import run_code, check_syntax_error
+from test.support import run_code, check_syntax_error, cpython_only
 
 
 class TypeAnnotationTests(unittest.TestCase):
@@ -109,6 +109,16 @@ class D(metaclass=C):
             del D.__annotations__
         self.assertEqual(D.__annotations__, {})
 
+    @cpython_only
+    def test_no_cell(self):
+        # gh-130924: Test that uses of annotations in local scopes do not
+        # create cell variables.
+        def f(x):
+            a: x
+            return x
+
+        self.assertEqual(f.__code__.co_cellvars, ())
+
 
 def build_module(code: str, name: str = "top") -> types.ModuleType:
     ns = run_code(code)
@@ -352,6 +362,7 @@ def test_no_exotic_expressions_in_unevaluated_annotations(self):
                 check_syntax_error(self, prelude + "(x): (yield)", "yield expression cannot be used within an annotation")
                 check_syntax_error(self, prelude + "(x): (yield from x)", "yield expression cannot be used within an annotation")
                 check_syntax_error(self, prelude + "(x): (y := 3)", "named expression cannot be used within an annotation")
+                check_syntax_error(self, prelude + "(x): (__debug__ := 3)", "named expression cannot be used within an annotation")
                 check_syntax_error(self, prelude + "(x): (await 42)", "await expression cannot be used within an annotation")
 
     def test_ignore_non_simple_annotations(self):

Misc/NEWS.d/next/Core_and_Builtins/2025-03-28-07-39-10.gh-issue-130924.l2Rbmj.rst

@@ -0,0 +1,3 @@
+Usage of a name in a function-scope annotation no longer triggers creation
+of a cell for that variable. This fixes a regression in earlier alphas of
+Python 3.14.

Python/symtable.c

@@ -141,6 +141,7 @@ ste_new(struct symtable *st, identifier name, _Py_block_ty block,
     ste->ste_needs_classdict = 0;
     ste->ste_has_conditional_annotations = 0;
     ste->ste_in_conditional_block = 0;
+    ste->ste_in_unevaluated_annotation = 0;
     ste->ste_annotation_block = NULL;
 
     ste->ste_has_docstring = 0;
@@ -2538,17 +2539,19 @@ symtable_visit_expr(struct symtable *st, expr_ty e)
             VISIT(st, expr, e->v.Slice.step);
         break;
     case Name_kind:
-        if (!symtable_add_def_ctx(st, e->v.Name.id,
-                                  e->v.Name.ctx == Load ? USE : DEF_LOCAL,
-                                  LOCATION(e), e->v.Name.ctx)) {
-            return 0;
-        }
-        /* Special-case super: it counts as a use of __class__ */
-        if (e->v.Name.ctx == Load &&
-            _PyST_IsFunctionLike(st->st_cur) &&
-            _PyUnicode_EqualToASCIIString(e->v.Name.id, "super")) {
-            if (!symtable_add_def(st, &_Py_ID(__class__), USE, LOCATION(e)))
+        if (!st->st_cur->ste_in_unevaluated_annotation) {
+            if (!symtable_add_def_ctx(st, e->v.Name.id,
+                                    e->v.Name.ctx == Load ? USE : DEF_LOCAL,
+                                    LOCATION(e), e->v.Name.ctx)) {
                 return 0;
+            }
+            /* Special-case super: it counts as a use of __class__ */
+            if (e->v.Name.ctx == Load &&
+                _PyST_IsFunctionLike(st->st_cur) &&
+                _PyUnicode_EqualToASCIIString(e->v.Name.id, "super")) {
+                if (!symtable_add_def(st, &_Py_ID(__class__), USE, LOCATION(e)))
+                    return 0;
+            }
         }
         break;
     /* child nodes of List and Tuple will have expr_context set */
@@ -2733,6 +2736,9 @@ symtable_visit_params(struct symtable *st, asdl_arg_seq *args)
 static int
 symtable_visit_annotation(struct symtable *st, expr_ty annotation, void *key)
 {
+    // Annotations in local scopes are not executed and should not affect the symtable
+    bool is_unevaluated = st->st_cur->ste_type == FunctionBlock;
+
     if ((st->st_cur->ste_type == ClassBlock || st->st_cur->ste_type == ModuleBlock)
             && st->st_cur->ste_in_conditional_block
             && !st->st_cur->ste_has_conditional_annotations)
@@ -2764,11 +2770,17 @@ symtable_visit_annotation(struct symtable *st, expr_ty annotation, void *key)
             return 0;
         }
     }
-    VISIT(st, expr, annotation);
+    if (is_unevaluated) {
+        st->st_cur->ste_in_unevaluated_annotation = 1;
+    }
+    int rc = symtable_visit_expr(st, annotation);
+    if (is_unevaluated) {
+        st->st_cur->ste_in_unevaluated_annotation = 0;
+    }
     if (!symtable_exit_block(st)) {
         return 0;
     }
-    return 1;
+    return rc;
 }
 
 static int