Auto merge of rust-lang#116163 - compiler-errors:lazyness, r=<try>

Don't store lazyness in `DefKind::TyAlias`

1. Don't store lazyness of a type alias in its `DefKind`, but instead via a query.
2. This allows us to treat type aliases as lazy if `#[feature(lazy_type_alias)]` *OR* if the alias contains a TAIT, rather than having checks for both in separate parts of the codebase.

r? `@oli-obk` cc `@fmease`

Author: bors

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -516,7 +516,7 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
                         // be the same as those of the ADT.
                         // FIXME: We should be able to do something similar to
                         // match_adt_and_segment in this case.
-                        Res::Def(DefKind::TyAlias { .. }, _) => (),
+                        Res::Def(DefKind::TyAlias, _) => (),
                         _ => {
                             if let Some(last_segment) = path.segments.last() {
                                 if let Some(highlight) = self.match_adt_and_segment(

compiler/rustc_hir/src/def.rs

@@ -61,9 +61,7 @@ pub enum DefKind {
     Variant,
     Trait,
     /// Type alias: `type Foo = Bar;`
-    TyAlias {
-        lazy: bool,
-    },
+    TyAlias,
     /// Type from an `extern` block.
     ForeignTy,
     /// Trait alias: `trait IntIterator = Iterator<Item = i32>;`
@@ -143,7 +141,7 @@ impl DefKind {
             DefKind::Ctor(CtorOf::Struct, CtorKind::Fn) => "tuple struct",
             DefKind::Ctor(CtorOf::Struct, CtorKind::Const) => "unit struct",
             DefKind::OpaqueTy => "opaque type",
-            DefKind::TyAlias { .. } => "type alias",
+            DefKind::TyAlias => "type alias",
             DefKind::TraitAlias => "trait alias",
             DefKind::AssocTy => "associated type",
             DefKind::Union => "union",
@@ -199,7 +197,7 @@ impl DefKind {
             | DefKind::Variant
             | DefKind::Trait
             | DefKind::OpaqueTy
-            | DefKind::TyAlias { .. }
+            | DefKind::TyAlias
             | DefKind::ForeignTy
             | DefKind::TraitAlias
             | DefKind::AssocTy
@@ -250,7 +248,7 @@ impl DefKind {
             | DefKind::Enum
             | DefKind::Variant
             | DefKind::Trait
-            | DefKind::TyAlias { .. }
+            | DefKind::TyAlias
             | DefKind::ForeignTy
             | DefKind::TraitAlias
             | DefKind::AssocTy