2 files changed, 9 insertions, 9 deletions
diff --git a/compiler/rustc_hir_typeck/src/cast.rs b/compiler/rustc_hir_typeck/src/cast.rs
index 59c06cbc5b5..8190095971b 100644
--- a/compiler/rustc_hir_typeck/src/cast.rs
+++ b/compiler/rustc_hir_typeck/src/cast.rs
@@ -721,13 +721,11 @@ impl<'a, 'tcx> CastCheck<'tcx> {
         use rustc_middle::ty::cast::IntTy::*;
 
         if self.cast_ty.is_dyn_star() {
-            if fcx.tcx.features().dyn_star() {
-                span_bug!(self.span, "should be handled by `coerce`");
-            } else {
-                // Report "casting is invalid" rather than "non-primitive cast"
-                // if the feature is not enabled.
-                return Err(CastError::IllegalCast);
-            }
+            // This coercion will fail if the feature is not enabled, OR
+            // if the coercion is (currently) illegal (e.g. `dyn* Foo + Send`
+            // to `dyn* Foo`). Report "casting is invalid" rather than
+            // "non-primitive cast".
+            return Err(CastError::IllegalCast);
         }
 
         let (t_from, t_cast) = match (CastTy::from_ty(self.expr_ty), CastTy::from_ty(self.cast_ty))
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index 541e16e42a7..f9e4a592d92 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -737,8 +737,10 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             return Err(TypeError::Mismatch);
         }
 
-        if let ty::Dynamic(a_data, _, _) = a.kind()
-            && let ty::Dynamic(b_data, _, _) = b.kind()
+        // FIXME(dyn_star): We should probably allow things like casting from
+        // `dyn* Foo + Send` to `dyn* Foo`.
+        if let ty::Dynamic(a_data, _, ty::DynStar) = a.kind()
+            && let ty::Dynamic(b_data, _, ty::DynStar) = b.kind()
             && a_data.principal_def_id() == b_data.principal_def_id()
         {
             return self.unify_and(a, b, |_| vec![]);