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dlr branch fix - Propagate exceptions from TryGetMember in tp_getattro_dlr_proxy #2718

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Merged
filmor merged 1 commit into from
May 11, 2026
Merged

dlr branch fix - Propagate exceptions from TryGetMember in tp_getattro_dlr_proxy #2718

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Propagate exceptions from TryGetMember in tp_getattro_dlr_proxy 
The dynamic getter swallowed any exception from TryGetMember and
returned default to Python with the prior AttributeError still set,
so user code observed a misleading AttributeError instead of the real
failure.

Set a Python exception in the catch arm. We use RuntimeError with the
message string rather than Converter.ToPython(e) because wrapping the
CLR exception object can trigger type initialisation that re-enters
this same slot on the live dynamic object, producing infinite
recursion.

Mirrors the symmetry already present in the setter (#2706 review,
@lostmsu) and adds a regression test alongside the existing
ThrowingSetDynamicObject coverage.
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@greateggsgreg
greateggsgreg committed May 9, 2026
commit 5d64310756dfb7a508b21836bc676d8144357b2f
7 changes: 6 additions & 1 deletion src/runtime/TypeManager.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -123,8 +123,13 @@ public static NewReference tp_getattro_dlr_proxy(BorrowedReference ob, BorrowedR
{
resolved = dynamicMemberAccessor.TryGetMember(dynamicObject, memberName, out value);
}
catch
catch (Exception e)
{
// Avoid wrapping the CLR exception via Converter.ToPython here: that would trigger
// CLR type initialisation which can re-enter this slot on the same live object,
// causing infinite recursion. A plain RuntimeError with the message is safe.
Runtime.PyErr_Clear();
Exceptions.SetError(Exceptions.RuntimeError, e.Message);
return default;
}

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6 changes: 6 additions & 0 deletions src/testing/dlrtest.cs
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Expand Up @@ -62,6 +62,12 @@ public override bool TrySetMember(SetMemberBinder binder, object value)
}
}

public class ThrowingGetDynamicObject : DynamicStorageObject
{
public override bool TryGetMember(GetMemberBinder binder, out object result)
=> throw new InvalidOperationException($"TryGetMember failed for '{binder.Name}'");
}

public class ThrowingSetDynamicObject : DynamicStorageObject
{
public override bool TrySetMember(SetMemberBinder binder, object value)
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9 changes: 9 additions & 0 deletions tests/test_dynamic.py
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Expand Up @@ -8,6 +8,7 @@
from Python.Test import RejectingDeleteDynamicObject
from Python.Test import RejectingSetDynamicObject
from Python.Test import ThrowingDeleteDynamicObject
from Python.Test import ThrowingGetDynamicObject
from Python.Test import ThrowingSetDynamicObject


Expand Down Expand Up @@ -186,6 +187,14 @@ def test_trysetmember_false_raises_attributeerror_instead_of_silent_python_setat
assert not hasattr(obj, "typoed_name")


def test_trygetmember_exception_is_raised_in_python():
obj = ThrowingGetDynamicObject()
obj.AddDynamicMember("any_key", 1)

with pytest.raises(Exception, match="TryGetMember failed for 'any_key'"):
_ = obj.any_key


def test_trysetmember_exception_is_raised_in_python():
obj = ThrowingSetDynamicObject()

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