change is_subtype to relate_types

1 files changed, 13 insertions, 4 deletions

diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs
index 6a5a3628617..4711f7b47cc 100644
--- a/compiler/rustc_const_eval/src/transform/validate.rs
+++ b/compiler/rustc_const_eval/src/transform/validate.rs
@@ -7,7 +7,7 @@ use rustc_infer::traits::Reveal;
 use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::mir::visit::{NonUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
-use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt, Variance};
 use rustc_mir_dataflow::impls::MaybeStorageLive;
 use rustc_mir_dataflow::storage::always_storage_live_locals;
 use rustc_mir_dataflow::{Analysis, ResultsCursor};
@@ -16,7 +16,7 @@ use rustc_target::spec::abi::Abi;
 
 use crate::util::is_within_packed;
 
-use crate::util::is_subtype;
+use crate::util::relate_types;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 enum EdgeKind {
@@ -604,7 +604,15 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             return true;
         }
 
-        return crate::util::is_subtype(self.tcx, self.param_env, src, dest);
+        // After borrowck subtyping should be fully explicit via
+        // `Subtype` projections.
+        let variance = if self.mir_phase >= MirPhase::Runtime(RuntimePhase::Initial) {
+            Variance::Invariant
+        } else {
+            Variance::Covariant
+        };
+
+        crate::util::relate_types(self.tcx, self.param_env, variance, src, dest)
     }
 }
 
@@ -756,9 +764,10 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 }
             }
             ProjectionElem::Subtype(ty) => {
-                if !is_subtype(
+                if !relate_types(
                     self.tcx,
                     self.param_env,
+                    Variance::Covariant,
                     ty,
                     place_ref.ty(&self.body.local_decls, self.tcx).ty,
                 ) {