#[cfg(feature = "nightly")]
use rustc_macros::{HashStable_NoContext, TyDecodable, TyEncodable};
use rustc_type_ir_macros::{TypeFoldable_Generic, TypeVisitable_Generic};
use crate::inherent::*;
use crate::{self as ty, Interner};
#[derive(derivative::Derivative)]
#[derivative(
Clone(bound = ""),
Hash(bound = ""),
PartialEq(bound = ""),
Eq(bound = ""),
Debug(bound = ""),
Copy(bound = "")
)]
#[derive(TypeVisitable_Generic, TypeFoldable_Generic)]
#[cfg_attr(feature = "nightly", derive(TyEncodable, TyDecodable, HashStable_NoContext))]
pub struct OpaqueTypeKey<I: Interner> {
pub def_id: I::LocalDefId,
pub args: I::GenericArgs,
}
impl<I: Interner> OpaqueTypeKey<I> {
pub fn iter_captured_args(self, cx: I) -> impl Iterator<Item = (usize, I::GenericArg)> {
let variances = cx.variances_of(self.def_id.into());
std::iter::zip(self.args.iter(), variances.iter()).enumerate().filter_map(
|(i, (arg, v))| match (arg.kind(), v) {
(_, ty::Invariant) => Some((i, arg)),
(ty::GenericArgKind::Lifetime(_), ty::Bivariant) => None,
_ => panic!("unexpected opaque type arg variance"),
},
)
}
pub fn fold_captured_lifetime_args(
self,
cx: I,
mut f: impl FnMut(I::Region) -> I::Region,
) -> Self {
let Self { def_id, args } = self;
let variances = cx.variances_of(def_id.into());
let args =
std::iter::zip(args.iter(), variances.iter()).map(|(arg, v)| match (arg.kind(), v) {
(ty::GenericArgKind::Lifetime(_), ty::Bivariant) => arg,
(ty::GenericArgKind::Lifetime(lt), _) => f(lt).into(),
_ => arg,
});
let args = cx.mk_args_from_iter(args);
Self { def_id, args }
}
}