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Handle non-string keys in class namespaces without panicking#6503

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copilot/fix-locals-value-panicked
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Handle non-string keys in class namespaces without panicking#6503
Copilot wants to merge 6 commits into
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copilot/fix-locals-value-panicked

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Copilot AI commented Dec 25, 2025 •
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Setting non-string keys in a class namespace (e.g., via locals()[42] = "abc") caused RustPython to panic; mappingproxy also ignored such entries.

  • Class namespace handling

    • Split string attributes from non-string entries when building types; keep non-string entries in a side dict to avoid panics.
    • Expose combined view via __dict__/mappingproxy so non-string keys are still reachable.

  • Mappingproxy behavior

    • Allow lookup, containment, and copy over the preserved non-string namespace entries.

  • Error messaging

    • dict.to_attributes now raises a clear TypeError for non-string attribute keys.

  • Regression coverage

    • Added snippet ensuring locals()[42] in a class ends up accessible via __dict__.

Example:

class B(object):
    locals()[42] = "abc"

assert B.__dict__[42] == "abc"
Original prompt

This section details on the original issue you should resolve

<issue_title>Setting locals() value leads to panicked.</issue_title>
<issue_description>In the following example, we set the locals()[42] as a string "abc" in a class A. Then it causes rustpython panicked.

test.py:


class A(object):
    locals()[42] = 'abc'

Behavior on rustpython(rustpython 0.1.2):

thread 'main' panicked at 'dict has non-string keys: [PyObject PyInt { value: 42 }]', vm/src/builtins/dict.rs:537:48
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Expected behavior(behavior on CPython 3.9.1):
work well on the Python interpreter

Step to reproduce:
type "cargo run --release test.py" on the console of Ubuntu 18.04 and MacOS Big Sur 11.7.1
rust version: rustc 1.65.0</issue_description>

<agent_instructions>The proper test is:

``
class A(object):
locals()['42'] = 'abc'


## Comments on the Issue (you are @copilot in this section)

<comments>
<comment_new><author>@DimitrisJim</author><body>
I honestly was not aware you could update the class `__dict__` this way. Another shorter repro is `type("A", (), {1:1})` with any other non string key for the dict.

We currently store the class namespace using a map with string keys. Weirdly enough no test cases for CPython test this as far as I could find. I doubt it could be considered an implementation detail, though.</body></comment_new>
</comments>

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Copilot AI and others added 5 commits December 25, 2025 01:56
@youknowone
Handle non-string class namespace keys safely
a334a92 
Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>
@youknowone
Refine non-string class dict handling
7b7fc3c 
Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>
@youknowone
Clone non-string attrs before erroring
cab7874 
Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>
@youknowone
Clarify non-string attribute expectation
1dfabee 
Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>
@youknowone
Tidy non-string attribute error handling
be3d647 
Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>
Copilot AI changed the title [WIP] Fix locals() value assignment causing panic Handle non-string keys in class namespaces without panicking Dec 25, 2025
Copilot AI requested a review from youknowone December 25, 2025 02:13
@youknowone youknowone closed this Mar 7, 2026
@youknowone youknowone deleted the copilot/fix-locals-value-panicked branch March 7, 2026 00:21
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Setting locals() value leads to panicked.

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