fix: update AST size assertions after enum layout changes

Account for the old bootstrap compiler still seeing the previous
Item and ItemKind sizes, while the new compiler sees the smaller
layouts produced by the enum layout optimization.

Update print-type-size output for enums that now fit in less space.

Signed-off-by: Vicente Gusmão <vicente.gusmao@tecnico.ulisboa.pt>
Co-authored-by: Miguel Marques <miguel.m.marques@tecnico.ulisboa.pt>

Author: VicenteGusmao

compiler/rustc_ast/src/ast.rs

@@ -4359,8 +4359,14 @@ mod size_asserts {
     static_assert_size!(GenericBound, 88);
     static_assert_size!(Generics, 40);
     static_assert_size!(Impl, 80);
+    #[cfg(bootstrap)]
     static_assert_size!(Item, 152);
+    #[cfg(not(bootstrap))]
+    static_assert_size!(Item, 144);
+    #[cfg(bootstrap)]
     static_assert_size!(ItemKind, 88);
+    #[cfg(not(bootstrap))]
+    static_assert_size!(ItemKind, 80);
     static_assert_size!(LitKind, 24);
     static_assert_size!(Local, 96);
     static_assert_size!(MetaItemLit, 40);

tests/ui/print_type_sizes/padding.stdout

@@ -1,21 +1,15 @@
-print-type-size type: `E1`: 12 bytes, alignment: 4 bytes
-print-type-size     discriminant: 1 bytes
-print-type-size     variant `B`: 11 bytes
-print-type-size         padding: 3 bytes
-print-type-size         field `.0`: 8 bytes, alignment: 4 bytes
-print-type-size     variant `A`: 7 bytes
+print-type-size type: `E1`: 8 bytes, alignment: 4 bytes
+print-type-size     variant `B`: 8 bytes
+print-type-size         field `.0`: 8 bytes
+print-type-size     variant `A`: 5 bytes
+print-type-size         field `.0`: 4 bytes
 print-type-size         field `.1`: 1 bytes
-print-type-size         padding: 2 bytes
-print-type-size         field `.0`: 4 bytes, alignment: 4 bytes
-print-type-size type: `E2`: 12 bytes, alignment: 4 bytes
-print-type-size     discriminant: 1 bytes
-print-type-size     variant `B`: 11 bytes
-print-type-size         padding: 3 bytes
-print-type-size         field `.0`: 8 bytes, alignment: 4 bytes
-print-type-size     variant `A`: 7 bytes
+print-type-size type: `E2`: 8 bytes, alignment: 4 bytes
+print-type-size     variant `B`: 8 bytes
+print-type-size         field `.0`: 8 bytes
+print-type-size     variant `A`: 5 bytes
+print-type-size         field `.1`: 4 bytes
 print-type-size         field `.0`: 1 bytes
-print-type-size         padding: 2 bytes
-print-type-size         field `.1`: 4 bytes, alignment: 4 bytes
 print-type-size type: `S`: 8 bytes, alignment: 4 bytes
 print-type-size     field `.g`: 4 bytes
 print-type-size     field `.a`: 1 bytes