rustdoc: Show type layout for type aliases

At first, you might think, "Why not just click through to the aliased
type?" But, if a type alias instantiates all of the generic parameters
of the aliased type, then it can show layout info even though the
aliased type cannot (because we can't compute layout for generic types).
So, I think it's useful to show layout info for type aliases.

This is a followup of 78d4b453ad2e19d44011b26fc55c949bff5dba3d
(originally part of rust-lang#83501).

Author: camelid

src/librustdoc/html/render/print_item.rs

@@ -976,6 +976,7 @@ fn item_typedef(
     // associated items from the aliased type (see discussion in #32077), but
     // we need #14072 to make sense of the generics.
     render_assoc_items(w, cx, it, def_id, AssocItemRender::All);
+    document_type_layout(w, cx, def_id);
 }
 
 fn item_union(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, s: &clean::Union) {

src/test/rustdoc/type-layout.rs

@@ -50,6 +50,18 @@ pub struct GenericLifetimes<'a>(&'a str);
 // @has - '(unsized)'
 pub struct Unsized([u8]);
 
+// @has type_layout/type.TypeAlias.html 'Size: '
+// @has - ' bytes'
+pub type TypeAlias = X;
+
+// @has type_layout/type.GenericTypeAlias.html 'Size: '
+// @has - '8 bytes'
+pub type GenericTypeAlias = (Generic<(u32, ())>, Generic<u32>);
+
+// Regression test for the rustdoc equivalent of #85103.
+// @has type_layout/type.Edges.html 'Encountered an error during type layout; the type failed to be normalized.'
+pub type Edges<'a, E> = std::borrow::Cow<'a, [E]>;
+
 // @!has type_layout/trait.MyTrait.html 'Size: '
 pub trait MyTrait {}