feat(any): make `Grouped` trait unsafe and encapsulate `AnyOutput`

fields

Declare `Grouped` as `unsafe trait` to make its soundness invariant
visible.
Make `AnyOutput.type_id` and `member_id` private; add public accessors
and
the `unsafe fn new_bare` constructor.

1 files changed, 5 insertions, 1 deletions

diff --git a/mingling_macros/src/func/group.rs b/mingling_macros/src/func/group.rs
index b865913..edb1fe1 100644
--- a/mingling_macros/src/func/group.rs
+++ b/mingling_macros/src/func/group.rs
@@ -133,7 +133,11 @@ pub(crate) fn group_macro(input: TokenStream) -> TokenStream {
             #type_use
             #alias_use
 
-            impl ::mingling::Grouped<__MinglingProgram> for #type_name {
+            /// SAFETY: This is an internal implementation of the `group!` macro,
+            /// guaranteeing that the enum value registered by the `register_type!` macro
+            /// is exactly the same as the actual return value,
+            /// which can be confirmed via the `Ident` in the `quote!` block.
+            unsafe impl ::mingling::Grouped<__MinglingProgram> for #type_name {
                 fn member_id() -> __MinglingProgram {
                     __MinglingProgram::#type_name
                 }