[lean backend] Add HasKind for Ty instead of having a pub field

Author: clementblaudeau

rust-engine/src/ast.rs

@@ -67,7 +67,7 @@ pub struct Region;
 
 /// A indirection for the representation of types.
 #[derive_group_for_ast]
-pub struct Ty(pub Box<TyKind>);
+pub struct Ty(Box<TyKind>);
 
 /// Describes any Rust type (e.g., `i32`, `Vec<T>`, `fn(i32) -> bool`).
 #[derive_group_for_ast]
@@ -1156,7 +1156,7 @@ pub enum AttributeKind {
     Tool {
         /// The path to the tool
         path: String,
-        /// The payload        
+        /// The payload
         tokens: String,
     },
     /// A doc comment
@@ -1540,5 +1540,15 @@ pub mod traits {
             }
         }
     }
+
+    /// Manual implementation of HasKind as the Ty struct contains a Box<TyKind>
+    /// instead of a TyKind directly.
+    impl HasKind for Ty {
+        type Kind = TyKind;
+
+        fn kind(&self) -> &Self::Kind {
+            &(*self.0)
+        }
+    }
 }
 pub use traits::*;

rust-engine/src/lean.rs

@@ -97,7 +97,7 @@ impl<'a, 'b> Pretty<'a, Allocator<Lean>, Span> for &'b ItemKind {
 
 impl<'a, 'b> Pretty<'a, Allocator<Lean>, Span> for &'b Ty {
     fn pretty(self, allocator: &'a Allocator<Lean>) -> DocBuilder<'a, Allocator<Lean>, Span> {
-        self.0.pretty(allocator)
+        self.kind().pretty(allocator)
     }
 }