Rollup merge of #146664 - fmease:clean-up-dyn, r=jdonszelmann

Clean up `ty::Dynamic`

1. As a follow-up to PR rust-lang/rust#143036, remove `DynKind` entirely.
2. Inside HIR ty lowering, consolidate modules `dyn_compatibility` and `lint` into `dyn_trait`
   * `dyn_compatibility` wasn't about dyn compatibility itself, it's about lowering trait object types
   * `lint` contained dyn-Trait-specific diagnostics+lints only

src/abi/mod.rs

@@ -715,7 +715,7 @@ pub(crate) fn codegen_drop<'tcx>(
         fx.bcx.ins().jump(ret_block, &[]);
     } else {
         match ty.kind() {
-            ty::Dynamic(_, _, ty::Dyn) => {
+            ty::Dynamic(_, _) => {
                 // IN THIS ARM, WE HAVE:
                 // ty = *mut (dyn Trait)
                 // which is: exists<T> ( *mut T,    Vtable<T: Trait> )

src/unsize.rs

@@ -30,9 +30,7 @@ pub(crate) fn unsized_info<'tcx>(
             fx.pointer_type,
             len.try_to_target_usize(fx.tcx).expect("expected monomorphic const in codegen") as i64,
         ),
-        (&ty::Dynamic(data_a, _, src_dyn_kind), &ty::Dynamic(data_b, _, target_dyn_kind))
-            if src_dyn_kind == target_dyn_kind =>
-        {
+        (&ty::Dynamic(data_a, _), &ty::Dynamic(data_b, _)) => {
             let old_info =
                 old_info.expect("unsized_info: missing old info for trait upcasting coercion");
             let b_principal_def_id = data_b.principal_def_id();

src/value_and_place.rs

@@ -909,8 +909,7 @@ pub(crate) fn assert_assignable<'tcx>(
             );
             // fn(&T) -> for<'l> fn(&'l T) is allowed
         }
-        (&ty::Dynamic(from_traits, _, _from_kind), &ty::Dynamic(to_traits, _, _to_kind)) => {
-            // FIXME(dyn-star): Do the right thing with DynKinds
+        (&ty::Dynamic(from_traits, _), &ty::Dynamic(to_traits, _)) => {
             for (from, to) in from_traits.iter().zip(to_traits) {
                 let from = fx.tcx.normalize_erasing_late_bound_regions(fx.typing_env(), from);
                 let to = fx.tcx.normalize_erasing_late_bound_regions(fx.typing_env(), to);