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generator fields are not necessarily initialized

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This commit is contained in:
Ralf Jung 2018-11-20 15:08:26 +01:00
parent 046e054a99
commit 6eeedbcd70
1 changed files with 22 additions and 11 deletions
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33
src/librustc_mir/interpret/visitor.rs
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@ -142,6 +142,7 @@ fn visit_value(&mut self, v: Self::V) -> EvalResult<'tcx>
self.walk_value(v)
}
/// Visit the given value as a union. No automatic recursion can happen here.
/// Also called for the fields of a generator, which may or may not be initialized.
#[inline(always)]
fn visit_union(&mut self, _v: Self::V) -> EvalResult<'tcx>
{
@ -291,17 +292,28 @@ fn walk_value(&mut self, v: Self::V) -> EvalResult<'tcx>
// use that as an unambiguous signal for detecting primitives. Make sure
// we did not miss any primitive.
debug_assert!(fields > 0);
self.visit_union(v)?;
self.visit_union(v)
},
layout::FieldPlacement::Arbitrary { ref offsets, .. } => {
// FIXME: We collect in a vec because otherwise there are lifetime errors:
// Projecting to a field needs (mutable!) access to `ecx`.
let fields: Vec<EvalResult<'tcx, Self::V>> =
(0..offsets.len()).map(|i| {
v.project_field(self.ecx(), i as u64)
})
.collect();
self.visit_aggregate(v, fields.into_iter())?;
// Special handling needed for generators: All but the first field
// (which is the state) are actually implicitly `MaybeUninit`, i.e.,
// they may or may not be initialized, so we cannot visit them.
match v.layout().ty.sty {
ty::Generator(..) => {
let field = v.project_field(self.ecx(), 0)?;
self.visit_aggregate(v, std::iter::once(Ok(field)))
}
_ => {
// FIXME: We collect in a vec because otherwise there are lifetime
// errors: Projecting to a field needs access to `ecx`.
let fields: Vec<EvalResult<'tcx, Self::V>> =
(0..offsets.len()).map(|i| {
v.project_field(self.ecx(), i as u64)
})
.collect();
self.visit_aggregate(v, fields.into_iter())
}
}
},
layout::FieldPlacement::Array { .. } => {
// Let's get an mplace first.
@ -317,10 +329,9 @@ fn walk_value(&mut self, v: Self::V) -> EvalResult<'tcx>
.map(|f| f.and_then(|f| {
Ok(Value::from_mem_place(f))
}));
self.visit_aggregate(v, iter)?;
self.visit_aggregate(v, iter)
}
}
Ok(())
}
}
}