Rollup merge of rust-lang#62261 - varkor:conservative_is_privately_un…

…inhabited-subst, r=oli-obk

Take substs into account in `conservative_is_privately_uninhabited`

src/librustc/ty/sty.rs

@@ -1704,22 +1704,21 @@ impl<'tcx> TyS<'tcx> {
     /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
     /// size, to account for partial initialisation. See #49298 for details.)
     pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx>) -> bool {
-        // FIXME(varkor): we can make this less conversative by substituting concrete
-        // type arguments.
         match self.sty {
             ty::Never => true,
             ty::Adt(def, _) if def.is_union() => {
                 // For now, `union`s are never considered uninhabited.
                 false
             }
-            ty::Adt(def, _) => {
+            ty::Adt(def, substs) => {
                 // Any ADT is uninhabited if either:
                 // (a) It has no variants (i.e. an empty `enum`);
                 // (b) Each of its variants (a single one in the case of a `struct`) has at least
                 //     one uninhabited field.
                 def.variants.iter().all(|var| {
                     var.fields.iter().any(|field| {
-                        tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx)
+                        tcx.type_of(field.did).subst(tcx, substs)
+                            .conservative_is_privately_uninhabited(tcx)
                     })
                 })
             }