Update compiler/rustc_mir/src/const_eval/mod.rs

Co-authored-by: Ralf Jung <post@ralfj.de>
This commit is contained in:
Oli Scherer 2021-03-16 18:26:09 +01:00 committed by GitHub
parent 1ffd21a15c
commit f0997fa1e8
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1 changed files with 4 additions and 5 deletions

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@ -84,11 +84,10 @@ fn const_to_valtree_inner<'tcx>(
Some(ty::ValTree::Leaf(val.assert_int()))
}
// Raw pointers are not allowed in type level constants, as raw pointers compare equal if
// their addresses are equal. Since we cannot guarantee any kind of pointer stability in
// the type system.
// Technically we could allow function pointers, but they are not guaranteed to be the
// same as the function pointers at runtime.
// Raw pointers are not allowed in type level constants, as we cannot properly test them for
// equality at compile-time (see `ptr_guaranteed_eq`/`_ne`).
// Technically we could allow function pointers (represented as `ty::Instance`), but this is not guaranteed to
// agree with runtime equality tests.
ty::FnPtr(_) | ty::RawPtr(_) => None,
ty::Ref(..) => unimplemented!("need to use deref_const"),