1 files changed, 42 insertions, 0 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
new file mode 100644
index 000000000..2a3319f0f
--- /dev/null
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
@@ -0,0 +1,42 @@
+use crate::infer::canonical::{Canonicalized, CanonicalizedQueryResponse};
+use crate::traits::query::Fallible;
+use rustc_infer::traits::query::OutlivesBound;
+use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt};
+
+#[derive(Copy, Clone, Debug, HashStable, TypeFoldable, TypeVisitable, Lift)]
+pub struct ImpliedOutlivesBounds<'tcx> {
+    pub ty: Ty<'tcx>,
+}
+
+impl<'tcx> super::QueryTypeOp<'tcx> for ImpliedOutlivesBounds<'tcx> {
+    type QueryResponse = Vec<OutlivesBound<'tcx>>;
+
+    fn try_fast_path(
+        _tcx: TyCtxt<'tcx>,
+        key: &ParamEnvAnd<'tcx, Self>,
+    ) -> Option<Self::QueryResponse> {
+        // Don't go into the query for things that can't possibly have lifetimes.
+        match key.value.ty.kind() {
+            ty::Tuple(elems) if elems.is_empty() => Some(vec![]),
+            ty::Never | ty::Str | ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) => {
+                Some(vec![])
+            }
+            _ => None,
+        }
+    }
+
+    fn perform_query(
+        tcx: TyCtxt<'tcx>,
+        canonicalized: Canonicalized<'tcx, ParamEnvAnd<'tcx, Self>>,
+    ) -> Fallible<CanonicalizedQueryResponse<'tcx, Self::QueryResponse>> {
+        // FIXME this `unchecked_map` is only necessary because the
+        // query is defined as taking a `ParamEnvAnd<Ty>`; it should
+        // take an `ImpliedOutlivesBounds` instead
+        let canonicalized = canonicalized.unchecked_map(|ParamEnvAnd { param_env, value }| {
+            let ImpliedOutlivesBounds { ty } = value;
+            param_env.and(ty)
+        });
+
+        tcx.implied_outlives_bounds(canonicalized)
+    }
+}