rustc_type_ir/
opaque_ty.rs

1use derive_where::derive_where;
2#[cfg(feature = "nightly")]
3use rustc_macros::{HashStable_NoContext, TyDecodable, TyEncodable};
4use rustc_type_ir_macros::{TypeFoldable_Generic, TypeVisitable_Generic};
5
6use crate::inherent::*;
7use crate::{self as ty, Interner};
8
9#[derive_where(Clone, Copy, Hash, PartialEq, Eq, Debug; I: Interner)]
10#[derive(TypeVisitable_Generic, TypeFoldable_Generic)]
11#[cfg_attr(feature = "nightly", derive(TyEncodable, TyDecodable, HashStable_NoContext))]
12pub struct OpaqueTypeKey<I: Interner> {
13    pub def_id: I::LocalDefId,
14    pub args: I::GenericArgs,
15}
16
17impl<I: Interner> OpaqueTypeKey<I> {
18    pub fn iter_captured_args(self, cx: I) -> impl Iterator<Item = (usize, I::GenericArg)> {
19        let variances = cx.variances_of(self.def_id.into());
20        std::iter::zip(self.args.iter(), variances.iter()).enumerate().filter_map(
21            |(i, (arg, v))| match (arg.kind(), v) {
22                (_, ty::Invariant) => Some((i, arg)),
23                (ty::GenericArgKind::Lifetime(_), ty::Bivariant) => None,
24                _ => panic!("unexpected opaque type arg variance"),
25            },
26        )
27    }
28
29    pub fn fold_captured_lifetime_args(
30        self,
31        cx: I,
32        mut f: impl FnMut(I::Region) -> I::Region,
33    ) -> Self {
34        let Self { def_id, args } = self;
35        let variances = cx.variances_of(def_id.into());
36        let args =
37            std::iter::zip(args.iter(), variances.iter()).map(|(arg, v)| match (arg.kind(), v) {
38                (ty::GenericArgKind::Lifetime(_), ty::Bivariant) => arg,
39                (ty::GenericArgKind::Lifetime(lt), _) => f(lt).into(),
40                _ => arg,
41            });
42        let args = cx.mk_args_from_iter(args);
43        Self { def_id, args }
44    }
45}
rustc_type_ir/opaque_ty.rs

rustc_type_ir/
opaque_ty.rs
