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unconditionally remap to nonconst in borrowck

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This commit is contained in:
Deadbeef 2022-09-15 15:48:35 +00:00
parent 31f259ce5a
commit 08aeb1aa9b
1 changed files with 6 additions and 18 deletions
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24
compiler/rustc_borrowck/src/type_check/mod.rs
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@ -424,31 +424,19 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
}
if let ty::FnDef(def_id, substs) = *constant.literal.ty().kind() {
// N.B.: When instantiating a trait method as a function item, it does not actually matter
// whether the trait is `const` or not, or whether `where T: ~const Tr` needs to be satisfied
// as `const`. If we were to introduce instantiating trait methods as `const fn`s, we would
// check that after this, either via a bound `where F: ~const FnOnce` or when coercing to a
// `const fn` pointer.
//
// FIXME(fee1-dead) FIXME(const_trait_impl): update this doc when trait methods can satisfy
// `~const FnOnce` or can be coerced to `const fn` pointer.
let const_norm = self.tcx().def_kind(def_id) == hir::def::DefKind::AssocFn
&& self.tcx().def_kind(ty::DefIdTree::parent(self.tcx(), def_id))
== hir::def::DefKind::Trait;
// const_trait_impl: use a non-const param env when checking that a FnDef type is well formed.
// this is because the well-formedness of the function does not need to be proved to have `const`
// impls for trait bounds.
let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs);
let prev = self.cx.param_env;
if const_norm {
self.cx.param_env = prev.without_const();
}
self.cx.param_env = prev.without_const();
self.cx.normalize_and_prove_instantiated_predicates(
def_id,
instantiated_predicates,
locations,
);
if const_norm {
self.cx.param_env = prev;
}
self.cx.param_env = prev;
}
}
}