pythongh-138349: Fix crash when combining module-level annotation and listcomp (python#138363)

Author: JelleZijlstra

Include/internal/pycore_magic_number.h

@@ -279,11 +279,13 @@ Known values:
     Python 3.14b1 3624 (Don't optimize LOAD_FAST when local is killed by DELETE_FAST)
     Python 3.14b3 3625 (Fix handling of opcodes that may leave operands on the stack when optimizing LOAD_FAST)
     Python 3.14rc2 3626 (Fix missing exception handlers in logical expression)
+    Python 3.14rc3 3627 (Fix miscompilation of some module-level annotations)
     Python 3.15a0 3650 (Initial version)
     Python 3.15a1 3651 (Simplify LOAD_CONST)
     Python 3.15a1 3652 (Virtual iterators)
     Python 3.15a1 3653 (Fix handling of opcodes that may leave operands on the stack when optimizing LOAD_FAST)
     Python 3.15a1 3654 (Fix missing exception handlers in logical expression)
+    Python 3.15a1 3655 (Fix miscompilation of some module-level annotations)
 
 
     Python 3.16 will start with 3700
@@ -297,7 +299,7 @@ PC/launcher.c must also be updated.
 
 */
 
-#define PYC_MAGIC_NUMBER 3654
+#define PYC_MAGIC_NUMBER 3655
 /* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
    (little-endian) and then appending b'\r\n'. */
 #define PYC_MAGIC_NUMBER_TOKEN \

Lib/test/test_type_annotations.py

@@ -835,3 +835,40 @@ def test_complex_comprehension_inlining_exec(self):
         genexp = annos["unique_name_2"][0]
         lamb = list(genexp)[0]
         self.assertEqual(lamb(), 42)
+
+    # gh-138349
+    def test_module_level_annotation_plus_listcomp(self):
+        cases = [
+            """
+            def report_error():
+                pass
+            try:
+                [0 for name_2 in unique_name_0 if (lambda: name_2)]
+            except:
+                pass
+            annotated_name: 0
+            """,
+            """
+            class Generic:
+                pass
+            try:
+                [0 for name_2 in unique_name_0 if (0 for unique_name_1 in unique_name_2 for unique_name_3 in name_2)]
+            except:
+                pass
+            annotated_name: 0
+            """,
+            """
+            class Generic:
+                pass
+            annotated_name: 0
+            try:
+                [0 for name_2 in [[0]] for unique_name_1 in unique_name_2 if (lambda: name_2)]
+            except:
+                pass
+            """,
+        ]
+        for code in cases:
+            with self.subTest(code=code):
+                mod = build_module(code)
+                annos = mod.__annotations__
+                self.assertEqual(annos, {"annotated_name": 0})

Misc/NEWS.d/next/Core_and_Builtins/2025-09-01-13-54-43.gh-issue-138349.0fGmAi.rst

@@ -0,0 +1,2 @@
+Fix crash in certain cases where a module contains both a module-level
+annotation and a comprehension.

Python/codegen.c

@@ -5477,10 +5477,12 @@ codegen_annassign(compiler *c, stmt_ty s)
                 RETURN_IF_ERROR(_PyCompile_AddDeferredAnnotation(
                     c, s, &conditional_annotation_index));
                 if (conditional_annotation_index != NULL) {
-                    ADDOP_NAME(
-                        c, loc,
-                        SCOPE_TYPE(c) == COMPILE_SCOPE_CLASS ? LOAD_DEREF : LOAD_NAME,
-                        &_Py_ID(__conditional_annotations__), cellvars);
+                    if (SCOPE_TYPE(c) == COMPILE_SCOPE_CLASS) {
+                        ADDOP_NAME(c, loc, LOAD_DEREF, &_Py_ID(__conditional_annotations__), cellvars);
+                    }
+                    else {
+                        ADDOP_NAME(c, loc, LOAD_NAME, &_Py_ID(__conditional_annotations__), names);
+                    }
                     ADDOP_LOAD_CONST_NEW(c, loc, conditional_annotation_index);
                     ADDOP_I(c, loc, SET_ADD, 1);
                     ADDOP(c, loc, POP_TOP);