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Fix except-star wrapper types and traceback #9646

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Merged
youknowone merged 2 commits into from
Nov 4, 2026
Merged

Fix except-star wrapper types and traceback #9646

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d01bd4b
Fix except-star wrapper types and traceback
youknowdot Nov 3, 2026
e32878d
Remove obsolete wrapped exception traceback expected failure
youknowdot Nov 3, 2026
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1 change: 0 additions & 1 deletion Lib/test/test_traceback.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3060,7 +3060,6 @@ def exc():
report = self.get_report(exc)
self.assertEqual(report, expected)

@unittest.expectedFailure # TODO: RUSTPYTHON
def test_exception_group_wrapped_naked(self):
# See gh-128799

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20 changes: 7 additions & 13 deletions crates/vm/src/exceptions.rs
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Expand Up @@ -3758,6 +3758,8 @@ fn check_except_star_type_valid(match_type: &PyObject, vm: &VirtualMachine) -> P

/// Match exception against except* handler type.
/// Returns (rest, match) tuple.
/// A caller matching a naked exception must attach the handler-frame
/// traceback to the resulting wrapper before exposing it.
pub fn exception_group_match(
exc_value: &PyObject,
match_type: &PyObject,
Expand All @@ -3780,18 +3782,10 @@ pub fn exception_group_match(
let matched = if is_eg {
exc_value.to_owned()
} else {
// Naked exception - wrap it in ExceptionGroup
// Naked exception: let BaseExceptionGroup choose the group type.
let excs = vm.ctx.new_tuple(vec![exc_value.to_owned()]);
let eg_type: PyObjectRef = crate::exception_group::exception_group().to_owned().into();
let wrapped = eg_type.call((vm.ctx.new_str(""), excs), vm)?;
// Copy traceback from original exception
if let Ok(exc) = exc_value.to_owned().downcast::<types::PyBaseException>()
&& let Some(tb) = exc.traceback()
&& let Ok(wrapped_exc) = wrapped.clone().downcast::<types::PyBaseException>()
{
wrapped_exc.set_traceback(Some(tb));
}
wrapped
let eg_type: PyObjectRef = vm.ctx.exceptions.base_exception_group.to_owned().into();
eg_type.call((vm.ctx.new_str(""), excs), vm)?
};
return Ok((vm.ctx.none(), matched));
}
Expand Down Expand Up @@ -3886,9 +3880,9 @@ pub fn prep_reraise_star(orig: &PyObject, excs: &PyObject, vm: &VirtualMachine)
return Ok(raised.into_iter().next().unwrap());
}

// Create new ExceptionGroup for multiple exceptions
// Let BaseExceptionGroup select ExceptionGroup when all children permit it.
let excs_tuple = vm.ctx.new_tuple(raised);
let eg_type: PyObjectRef = crate::exception_group::exception_group().to_owned().into();
let eg_type: PyObjectRef = vm.ctx.exceptions.base_exception_group.to_owned().into();
eg_type.call((vm.ctx.new_str(""), excs_tuple), vm)
}

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17 changes: 17 additions & 0 deletions crates/vm/src/frame.rs
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Expand Up @@ -4658,6 +4658,8 @@ impl ExecutingFrame<'_> {
Instruction::CheckEgMatch => {
let match_type = self.pop_value();
let exc_value = self.pop_value();
let naked = !vm.is_none(&exc_value)
&& !exc_value.fast_isinstance(vm.ctx.exceptions.base_exception_group);
let (rest, matched) =
crate::exceptions::exception_group_match(&exc_value, &match_type, vm)?;

Expand All @@ -4666,6 +4668,21 @@ impl ExecutingFrame<'_> {
if !vm.is_none(&matched)
&& let Some(exc) = matched.downcast_ref::<PyBaseException>()
{
if naked {
// CPython gives a newly wrapped exception its own
// traceback at the except* handler, not the child's
// original traceback.
let idx = self.lasti().saturating_sub(1) as usize;
if let Some((loc, _)) = self.code.locations.get(idx) {
let tb = PyTraceback::new(
None,
self.frame_object(vm),
idx as i32 * 2,
loc.line,
);
exc.set_traceback(Some(tb.into_ref(&vm.ctx)));
}
}
vm.set_exception(Some(exc.to_owned()));
}

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