1 files changed, 55 insertions, 0 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs
new file mode 100644
index 000000000..b63382429
--- /dev/null
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs
@@ -0,0 +1,55 @@
+use crate::infer::canonical::{Canonicalized, CanonicalizedQueryResponse};
+use crate::traits::query::dropck_outlives::{trivial_dropck_outlives, DropckOutlivesResult};
+use crate::traits::query::Fallible;
+use rustc_middle::ty::{ParamEnvAnd, Ty, TyCtxt};
+
+#[derive(Copy, Clone, Debug, HashStable, TypeFoldable, TypeVisitable, Lift)]
+pub struct DropckOutlives<'tcx> {
+    dropped_ty: Ty<'tcx>,
+}
+
+impl<'tcx> DropckOutlives<'tcx> {
+    pub fn new(dropped_ty: Ty<'tcx>) -> Self {
+        DropckOutlives { dropped_ty }
+    }
+}
+
+impl<'tcx> super::QueryTypeOp<'tcx> for DropckOutlives<'tcx> {
+    type QueryResponse = DropckOutlivesResult<'tcx>;
+
+    fn try_fast_path(
+        tcx: TyCtxt<'tcx>,
+        key: &ParamEnvAnd<'tcx, Self>,
+    ) -> Option<Self::QueryResponse> {
+        if trivial_dropck_outlives(tcx, key.value.dropped_ty) {
+            Some(DropckOutlivesResult::default())
+        } else {
+            None
+        }
+    }
+
+    fn perform_query(
+        tcx: TyCtxt<'tcx>,
+        canonicalized: Canonicalized<'tcx, ParamEnvAnd<'tcx, Self>>,
+    ) -> Fallible<CanonicalizedQueryResponse<'tcx, Self::QueryResponse>> {
+        // Subtle: note that we are not invoking
+        // `infcx.at(...).dropck_outlives(...)` here, but rather the
+        // underlying `dropck_outlives` query. This same underlying
+        // query is also used by the
+        // `infcx.at(...).dropck_outlives(...)` fn. Avoiding the
+        // wrapper means we don't need an infcx in this code, which is
+        // good because the interface doesn't give us one (so that we
+        // know we are not registering any subregion relations or
+        // other things).
+
+        // FIXME convert to the type expected by the `dropck_outlives`
+        // query. This should eventually be fixed by changing the
+        // *underlying query*.
+        let canonicalized = canonicalized.unchecked_map(|ParamEnvAnd { param_env, value }| {
+            let DropckOutlives { dropped_ty } = value;
+            param_env.and(dropped_ty)
+        });
+
+        tcx.dropck_outlives(canonicalized)
+    }
+}