gh-132002: Fix crash of ContextVar on unhashable str subtype

Lib/test/test_context.py

@@ -92,6 +92,15 @@ def test_context_new_1(self):
             contextvars.Context(a=1)
         contextvars.Context(**{})
 
+    def test_context_new_unhashable_str_subclass(self):
+        # gh-132002: it used to crash on unhashable str subtypes.
+        class weird_str(str):
+            def __eq__(self, other):
+                pass
+
+        with self.assertRaisesRegex(TypeError, 'unhashable type'):
+            contextvars.ContextVar(weird_str())
+
     def test_context_typerrors_1(self):
         ctx = contextvars.Context()
 

Misc/NEWS.d/next/Library/2025-04-02-11-31-15.gh-issue-132002.TMsYvE.rst

@@ -0,0 +1,2 @@
+Fix crash when deallocating :class:`contextvars.ContextVar` with weird
+unahashable string names.

Python/context.c

@@ -880,7 +880,7 @@ contextvar_new(PyObject *name, PyObject *def)
 
     var->var_hash = contextvar_generate_hash(var, name);
     if (var->var_hash == -1) {
-        Py_DECREF(var);
+        PyObject_GC_Del(var);
         return NULL;
     }