clean up ADT sized constraint computation

3 files changed, 7 insertions, 7 deletions

diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 865299e15c8..c73dc7cd281 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -703,8 +703,8 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    query adt_sized_constraint(key: DefId) -> ty::EarlyBinder<&'tcx ty::List<Ty<'tcx>>> {
-        desc { |tcx| "computing `Sized` constraints for `{}`", tcx.def_path_str(key) }
+    query adt_sized_constraint(key: DefId) -> Option<ty::EarlyBinder<Ty<'tcx>>> {
+        desc { |tcx| "computing `Sized` constraint for `{}`", tcx.def_path_str(key) }
     }
 
     query adt_dtorck_constraint(
diff --git a/compiler/rustc_middle/src/ty/adt.rs b/compiler/rustc_middle/src/ty/adt.rs
index 36050792adc..a7144316769 100644
--- a/compiler/rustc_middle/src/ty/adt.rs
+++ b/compiler/rustc_middle/src/ty/adt.rs
@@ -590,10 +590,10 @@ impl<'tcx> AdtDef<'tcx> {
         tcx.adt_destructor(self.did())
     }
 
-    /// Returns a list of types such that `Self: Sized` if and only if that
-    /// type is `Sized`, or `ty::Error` if this type has a recursive layout.
-    pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> ty::EarlyBinder<&'tcx ty::List<Ty<'tcx>>> {
-        tcx.adt_sized_constraint(self.did())
+    /// Returns a type such that `Self: Sized` if and only if that type is `Sized`,
+    /// or `None` if the type is always sized.
+    pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> Option<ty::EarlyBinder<Ty<'tcx>>> {
+        if self.is_struct() { tcx.adt_sized_constraint(self.did()) } else { None }
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 11065b2a382..7ff0b8dac4c 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -2490,7 +2490,7 @@ impl<'tcx> Ty<'tcx> {
 
             ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
 
-            ty::Adt(def, _args) => def.sized_constraint(tcx).skip_binder().is_empty(),
+            ty::Adt(def, _args) => def.sized_constraint(tcx).is_none(),
 
             ty::Alias(..) | ty::Param(_) | ty::Placeholder(..) | ty::Bound(..) => false,