Fix undefined left shifts in stack_swap() (Objects/frameobject.c)

Lib/test/test_frame.py

@@ -1,10 +1,11 @@
 import copy
 import operator
 import re
 import sys
 import textwrap
 import threading
 import unittest
+import warnings
 import weakref
 try:
     import _testcapi
@@ -222,6 +223,30 @@
         with self.assertRaises(AttributeError):
             del f.f_lineno
 
+    def test_f_lineno_deep_stack_swap(self):
+        fors = " ".join(f"for v{i} in range(1)" for i in range(11))
+        params = ", ".join(f"v{i}=None" for i in range(11))
+        ns = {}
+        exec(f"def f({params}):\n    return [0 {fors}]\n", ns)
+        f = ns["f"]
+
+        jumped = []
+
+        def tracer(frame, event, arg):
+            if (event == 'line' and frame.f_code is f.__code__
+                    and not jumped):
+                jumped.append(None)
+                frame.f_lineno = frame.f_lineno
+            return tracer
+
+        with warnings.catch_warnings():
+            warnings.simplefilter('ignore', RuntimeWarning)
+            sys.settrace(tracer)
+            try:
+                self.assertEqual(f(), [0])
+            finally:
+                sys.settrace(None)
+
     def test_f_trace(self):
         f, _, _ = self.make_frames()
         def tracer(*args):

Objects/frameobject.c

@@ -1320,7 +1320,8 @@ stack_swap(int64_t stack, int n)
     Kind to_swap = peek(stack, n);
     Kind top = top_of_stack(stack);
     int shift = BITS_PER_BLOCK*(n-1);
-    int64_t replaced_low = (stack & ~(MASK << shift)) | (top << shift);
+    int64_t replaced_low = (stack & ~((int64_t)MASK << shift))
+                           | ((int64_t)top << shift);
     int64_t replaced_top = (replaced_low & ~MASK) | to_swap;
     return replaced_top;
 }