[3.14] gh-135450: Remove assertion in _PyCode_CheckNoExternalState (gh-135694)

miss-islington · ZeroIntensity · web-flow · commit c03f94e7fe2f · 2025-06-18T23:57:18.000Z
The assertion reflected a misunderstanding of situations where "hidden" variables might exist, namely generator expressions and comprehensions. (cherry picked from commit 15f2bac, AKA gh-135466) Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
diff --git a/Lib/test/test_interpreters/test_api.py b/Lib/test/test_interpreters/test_api.py
@@ -944,6 +944,22 @@ def test_created_with_capi(self):
             with self.assertRaisesRegex(InterpreterError, 'unrecognized'):
                 interp.exec('raise Exception("it worked!")')
 
+    def test_list_comprehension(self):
+        # gh-135450: List comprehensions caused an assertion failure
+        # in _PyCode_CheckNoExternalState()
+        import string
+        r_interp, w_interp = self.pipe()
+
+        interp = interpreters.create()
+        interp.exec(f"""if True:
+            import os
+            comp = [str(i) for i in range(10)]
+            os.write({w_interp}, ''.join(comp).encode())
+        """)
+        self.assertEqual(os.read(r_interp, 10).decode(), string.digits)
+        interp.close()
+
+
     # test__interpreters covers the remaining
     # Interpreter.exec() behavior.
 
diff --git a/Objects/codeobject.c b/Objects/codeobject.c
@@ -1999,7 +1999,6 @@ _PyCode_CheckNoExternalState(PyCodeObject *co, _PyCode_var_counts_t *counts,
                              const char **p_errmsg)
 {
     const char *errmsg = NULL;
-    assert(counts->locals.hidden.total == 0);
     if (counts->numfree > 0) {  // It's a closure.
         errmsg = "closures not supported";
     }

Original file line number	Diff line number	Diff line change
`@@ -1999,7 +1999,6 @@ _PyCode_CheckNoExternalState(PyCodeObject co, _PyCode_var_counts_t counts,`
`1999`	`1999`	`const char **p_errmsg)`
`2000`	`2000`	`{`
`2001`	`2001`	`const char *errmsg = NULL;`
`2002`		`- assert(counts->locals.hidden.total == 0);`
`2003`	`2002`	`if (counts->numfree > 0) { // It's a closure.`
`2004`	`2003`	`errmsg = "closures not supported";`
`2005`	`2004`	`}`