[PATCH 1/3] rust: macros: vtable: hide generated `HAS_` constants for required methods

[Gary Guo <gary@garyguo.net>]

These constants have to be generated as the implementation-site `#[vtable]`
invocation has no way of knowing whether the methods are required or
provided-but-overriden. However, these constants will have a fixed value so
shouldn't be used. Thus, hide them.

Signed-off-by: Gary Guo <gary@garyguo.net>
---
 rust/macros/vtable.rs | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/rust/macros/vtable.rs b/rust/macros/vtable.rs
index c6510b0c4ea1..e28976a5919f 100644
--- a/rust/macros/vtable.rs
+++ b/rust/macros/vtable.rs
@@ -9,7 +9,10 @@
     Ident,
     TokenStream, //
 };
-use quote::ToTokens;
+use quote::{
+    quote,
+    ToTokens, //
+};
 use syn::{
     parse_quote,
     Error,
@@ -40,12 +43,18 @@ fn handle_trait(mut item: ItemTrait) -> Result<ItemTrait> {
 
             // We don't know on the implementation-site whether a method is required or provided
             // so we have to generate a const for all methods.
+            // However, hide it for required methods as it will always be true.
+            let doc = if fn_item.default.is_some() {
+                let comment =
+                    format!("Indicates if the `{name}` method is overridden by the implementor.");
+                quote!(#[doc = #comment])
+            } else {
+                quote!(#[doc(hidden)])
+            };
             let cfg_attrs = crate::helpers::gather_cfg_attrs(&fn_item.attrs);
-            let comment =
-                format!("Indicates if the `{name}` method is overridden by the implementor.");
             gen_items.push(parse_quote! {
                 #(#cfg_attrs)*
-                #[doc = #comment]
+                #doc
                 const #gen_const_name: bool = false;
             });
         }

-- 
2.54.0