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Clarify order of operations during interning

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Co-authored-by: Ralf Jung <post@ralfj.de>
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Oli Scherer 2024-02-05 22:21:40 +01:00 committed by GitHub
parent 5d46b982c5
commit c94769a974
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7
compiler/rustc_const_eval/src/interpret/intern.rs
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@ -148,6 +148,13 @@ pub fn intern_const_alloc_recursive<
// better errors. Maybe we should consider doing validation before interning in the future.
while let Some(prov) = todo.pop() {
let alloc_id = prov.alloc_id();
// Crucially, we check this *before* checking whether the `alloc_id`
// has already been interned. The point of this check is to ensure that when
// there are multiple pointers to the same allocation, they are *all* immutable.
// Therefore it would be bad if we only checked the first pointer to any given
// allocation.
// (It is likely not possible to actually have multiple pointers to the same allocation,
// so alternatively we could also check that and ICE if there are multiple such pointers.)
if intern_kind != InternKind::Promoted
&& inner_mutability == Mutability::Not
&& !prov.immutable()