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-rw-r--r--compiler/rustc_hir_analysis/src/astconv/mod.rs17
-rw-r--r--compiler/rustc_hir_analysis/src/check/check.rs2
-rw-r--r--compiler/rustc_hir_analysis/src/check/wfcheck.rs10
-rw-r--r--compiler/rustc_hir_analysis/src/collect.rs1
-rw-r--r--compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs4
-rw-r--r--compiler/rustc_hir_analysis/src/collect/type_of.rs22
-rw-r--r--compiler/rustc_hir_analysis/src/variance/constraints.rs10
-rw-r--r--compiler/rustc_hir_analysis/src/variance/mod.rs6
-rw-r--r--compiler/rustc_hir_analysis/src/variance/terms.rs6
9 files changed, 42 insertions, 36 deletions
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 106cd223d30..e35d47f16d8 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -909,23 +909,16 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let tcx = self.tcx();
         let args = self.ast_path_args_for_ty(span, did, item_segment);
 
-        if let DefKind::TyAlias { lazy: true } = tcx.def_kind(did) {
+        if let DefKind::TyAlias = tcx.def_kind(did)
+            && tcx.type_alias_is_lazy(did)
+        {
             // Type aliases defined in crates that have the
             // feature `lazy_type_alias` enabled get encoded as a type alias that normalization will
             // then actually instantiate the where bounds of.
             let alias_ty = tcx.mk_alias_ty(did, args);
             Ty::new_alias(tcx, ty::Weak, alias_ty)
         } else {
-            let ty = tcx.at(span).type_of(did);
-            if ty.skip_binder().has_opaque_types() {
-                // Type aliases referring to types that contain opaque types (but aren't just directly
-                // referencing a single opaque type) get encoded as a type alias that normalization will
-                // then actually instantiate the where bounds of.
-                let alias_ty = tcx.mk_alias_ty(did, args);
-                Ty::new_alias(tcx, ty::Weak, alias_ty)
-            } else {
-                ty.instantiate(tcx, args)
-            }
+            tcx.at(span).type_of(did).instantiate(tcx, args)
         }
     }
 
@@ -2164,7 +2157,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             }
             Res::Def(
                 DefKind::Enum
-                | DefKind::TyAlias { .. }
+                | DefKind::TyAlias
                 | DefKind::Struct
                 | DefKind::Union
                 | DefKind::ForeignTy,
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 564206f9e4b..eb1f48d23ff 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -640,7 +640,7 @@ fn check_item_type(tcx: TyCtxt<'_>, id: hir::ItemId) {
                 check_opaque(tcx, id);
             }
         }
-        DefKind::TyAlias { .. } => {
+        DefKind::TyAlias => {
             let pty_ty = tcx.type_of(id.owner_id).instantiate_identity();
             let generics = tcx.generics_of(id.owner_id);
             check_type_params_are_used(tcx, &generics, pty_ty);
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index 00a684f2963..b7b162ce27b 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -246,9 +246,7 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) {
         // `ForeignItem`s are handled separately.
         hir::ItemKind::ForeignMod { .. } => {}
         hir::ItemKind::TyAlias(hir_ty, ast_generics) => {
-            if tcx.features().lazy_type_alias
-                || tcx.type_of(item.owner_id).skip_binder().has_opaque_types()
-            {
+            if tcx.type_alias_is_lazy(item.owner_id) {
                 // Bounds of lazy type aliases and of eager ones that contain opaque types are respected.
                 // E.g: `type X = impl Trait;`, `type X = (impl Trait, Y);`.
                 check_item_type(tcx, def_id, hir_ty.span, UnsizedHandling::Allow);
@@ -1711,10 +1709,8 @@ fn check_variances_for_type_defn<'tcx>(
             }
         }
         ItemKind::TyAlias(..) => {
-            let ty = tcx.type_of(item.owner_id).instantiate_identity();
-
-            if tcx.features().lazy_type_alias || ty.has_opaque_types() {
-                if ty.references_error() {
+            if tcx.type_alias_is_lazy(item.owner_id) {
+                if tcx.type_of(item.owner_id).skip_binder().references_error() {
                     return;
                 }
             } else {
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 01e40c62a8b..cd37221ae6f 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -58,6 +58,7 @@ pub fn provide(providers: &mut Providers) {
     *providers = Providers {
         type_of: type_of::type_of,
         type_of_opaque: type_of::type_of_opaque,
+        type_alias_is_lazy: type_of::type_alias_is_lazy,
         item_bounds: item_bounds::item_bounds,
         explicit_item_bounds: item_bounds::explicit_item_bounds,
         generics_of: generics_of::generics_of,
diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
index d9207f2de52..eb4466449a0 100644
--- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
+++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
@@ -1519,7 +1519,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
                 DefKind::Struct
                 | DefKind::Union
                 | DefKind::Enum
-                | DefKind::TyAlias { .. }
+                | DefKind::TyAlias
                 | DefKind::Trait,
                 def_id,
             ) if depth == 0 => Some(def_id),
@@ -2029,7 +2029,7 @@ fn is_late_bound_map(
 
                 hir::TyKind::Path(hir::QPath::Resolved(
                     None,
-                    hir::Path { res: Res::Def(DefKind::TyAlias { .. }, alias_def), segments, span },
+                    hir::Path { res: Res::Def(DefKind::TyAlias, alias_def), segments, span },
                 )) => {
                     // See comments on `ConstrainedCollectorPostAstConv` for why this arm does not just consider
                     // args to be unconstrained.
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index d12337687e2..ae62119b182 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -623,3 +623,25 @@ fn check_feature_inherent_assoc_ty(tcx: TyCtxt<'_>, span: Span) {
         .emit();
     }
 }
+
+pub fn type_alias_is_lazy<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> bool {
+    use hir::intravisit::Visitor;
+    if tcx.features().lazy_type_alias {
+        return true;
+    }
+    struct HasTait {
+        has_type_alias_impl_trait: bool,
+    }
+    impl<'tcx> Visitor<'tcx> for HasTait {
+        fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
+            if let hir::TyKind::OpaqueDef(..) = t.kind {
+                self.has_type_alias_impl_trait = true;
+            } else {
+                hir::intravisit::walk_ty(self, t);
+            }
+        }
+    }
+    let mut has_tait = HasTait { has_type_alias_impl_trait: false };
+    has_tait.visit_ty(tcx.hir().expect_item(def_id).expect_ty_alias().0);
+    has_tait.has_type_alias_impl_trait
+}
diff --git a/compiler/rustc_hir_analysis/src/variance/constraints.rs b/compiler/rustc_hir_analysis/src/variance/constraints.rs
index 9aac7160f2e..61d9c989e2f 100644
--- a/compiler/rustc_hir_analysis/src/variance/constraints.rs
+++ b/compiler/rustc_hir_analysis/src/variance/constraints.rs
@@ -6,7 +6,7 @@
 use hir::def_id::{DefId, LocalDefId};
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::ty::{GenericArgKind, GenericArgsRef};
 
 use super::terms::VarianceTerm::*;
@@ -78,9 +78,7 @@ pub fn add_constraints_from_crate<'a, 'tcx>(
                 }
             }
             DefKind::Fn | DefKind::AssocFn => constraint_cx.build_constraints_for_item(def_id),
-            DefKind::TyAlias { lazy }
-                if lazy || tcx.type_of(def_id).instantiate_identity().has_opaque_types() =>
-            {
+            DefKind::TyAlias if tcx.type_alias_is_lazy(def_id) => {
                 constraint_cx.build_constraints_for_item(def_id)
             }
             _ => {}
@@ -110,8 +108,8 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
 
         // The type as returned by `type_of` is the underlying type and generally not a weak projection.
         // Therefore we need to check the `DefKind` first.
-        if let DefKind::TyAlias { lazy } = tcx.def_kind(def_id)
-            && (lazy || ty.has_opaque_types())
+        if let DefKind::TyAlias = tcx.def_kind(def_id)
+            && tcx.type_alias_is_lazy(def_id)
         {
             self.add_constraints_from_ty(current_item, ty, self.covariant);
             return;
diff --git a/compiler/rustc_hir_analysis/src/variance/mod.rs b/compiler/rustc_hir_analysis/src/variance/mod.rs
index d69d7ff904a..85e0000ab47 100644
--- a/compiler/rustc_hir_analysis/src/variance/mod.rs
+++ b/compiler/rustc_hir_analysis/src/variance/mod.rs
@@ -8,7 +8,7 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, CrateVariancesMap, GenericArgsRef, Ty, TyCtxt};
-use rustc_middle::ty::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt};
+use rustc_middle::ty::{TypeSuperVisitable, TypeVisitable};
 use std::ops::ControlFlow;
 
 /// Defines the `TermsContext` basically houses an arena where we can
@@ -56,9 +56,7 @@ fn variances_of(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Variance] {
             let crate_map = tcx.crate_variances(());
             return crate_map.variances.get(&item_def_id.to_def_id()).copied().unwrap_or(&[]);
         }
-        DefKind::TyAlias { lazy }
-            if lazy || tcx.type_of(item_def_id).instantiate_identity().has_opaque_types() =>
-        {
+        DefKind::TyAlias if tcx.type_alias_is_lazy(item_def_id) => {
             // These are inferred.
             let crate_map = tcx.crate_variances(());
             return crate_map.variances.get(&item_def_id.to_def_id()).copied().unwrap_or(&[]);
diff --git a/compiler/rustc_hir_analysis/src/variance/terms.rs b/compiler/rustc_hir_analysis/src/variance/terms.rs
index 1a8ec5f0853..275df24956c 100644
--- a/compiler/rustc_hir_analysis/src/variance/terms.rs
+++ b/compiler/rustc_hir_analysis/src/variance/terms.rs
@@ -12,7 +12,7 @@
 use rustc_arena::DroplessArena;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{LocalDefId, LocalDefIdMap};
-use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, TyCtxt};
 use std::fmt;
 
 use self::VarianceTerm::*;
@@ -97,9 +97,7 @@ pub fn determine_parameters_to_be_inferred<'a, 'tcx>(
                 }
             }
             DefKind::Fn | DefKind::AssocFn => terms_cx.add_inferreds_for_item(def_id),
-            DefKind::TyAlias { lazy }
-                if lazy || tcx.type_of(def_id).instantiate_identity().has_opaque_types() =>
-            {
+            DefKind::TyAlias if tcx.type_alias_is_lazy(def_id) => {
                 terms_cx.add_inferreds_for_item(def_id)
             }
             _ => {}