gh-55664: Add warning when creating a type using a namespace dictionary with non-string keys. (GH-105338)

Co-authored-by: Daniel Urban <durban@users.noreply.github.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 114cf21..a850473 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -3828,6 +3828,17 @@ type_new_impl(type_new_ctx *ctx)
     // Put the proper slots in place
     fixup_slot_dispatchers(type);
 
+    if (!_PyDict_HasOnlyStringKeys(type->tp_dict)) {
+        if (PyErr_WarnFormat(
+                PyExc_RuntimeWarning,
+                1,
+                "non-string key in the __dict__ of class %.200s",
+                type->tp_name) == -1)
+        {
+            goto error;
+        }
+    }
+
     if (type_new_set_names(type) < 0) {
         goto error;
     }