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Co-authored-by: Jonas Platte <[email protected]>
mozilla · Jun 14, 2023 · 708a858 · 708a858
1 parent 7d5c4f8
commit 708a858
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Showing 3 changed files with 14 additions and 26 deletions.
diff --git a/docs/manual/src/proc_macro/index.md b/docs/manual/src/proc_macro/index.md
@@ -242,8 +242,8 @@ pub trait Person {
 
 // Corresponding UDL:
 // callback interface Person {
-//   string name();
-//   u32 age();
+//     string name();
+//     u32 age();
 // }
 }
 ```

diff --git a/uniffi_macros/src/enum_.rs b/uniffi_macros/src/enum_.rs
@@ -221,15 +221,10 @@ pub fn variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStream>> {
 /// implementation which panics.
 pub(crate) fn handle_callback_unexpected_error_fn(
     handle_unknown_callback_error: bool,
-) -> TokenStream {
-    if handle_unknown_callback_error {
-        quote! {
-            fn handle_callback_unexpected_error(e: ::uniffi::UnexpectedUniFFICallbackError) -> Self {
-                <Self as ::std::convert::From<::uniffi::UnexpectedUniFFICallbackError>>::from(e)
-            }
+) -> Option<TokenStream> {
+    handle_unknown_callback_error.then(|| quote! {
+        fn handle_callback_unexpected_error(e: ::uniffi::UnexpectedUniFFICallbackError) -> Self {
+            <Self as ::std::convert::From<::uniffi::UnexpectedUniFFICallbackError>>::from(e)
         }
-    } else {
-        // Use the default function
-        quote! {}
-    }
+    })
 }
diff --git a/uniffi_macros/src/export/callback_interface.rs b/uniffi_macros/src/export/callback_interface.rs
@@ -25,7 +25,7 @@ pub(super) fn trait_impl(
             ImplItem::Method(sig) => gen_method_impl(sig, internals_ident),
             _ => unreachable!("traits have no constructors"),
         })
-        .collect::<syn::Result<Vec<_>>>()?;
+        .collect::<syn::Result<TokenStream>>()?;
 
     Ok(quote! {
         #[doc(hidden)]
@@ -40,7 +40,7 @@ pub(super) fn trait_impl(
             }
         }
 
-        impl Drop for #ident {
+        impl ::std::mem::Drop for #ident {
             fn drop(&mut self) {
                 #internals_ident.invoke_callback::<(), crate::UniFfiTag>(
                     self.handle, uniffi::IDX_CALLBACK_FREE, Default::default()
@@ -51,7 +51,7 @@ pub(super) fn trait_impl(
         ::uniffi::deps::static_assertions::assert_impl_all!(#ident: Send);
 
         impl #trait_ident for #ident {
-            #(#trait_impl_methods)*
+            #trait_impl_methods
         }
 
         ::uniffi::ffi_converter_callback_interface!(#trait_ident, #ident, #trait_name, crate::UniFfiTag);
@@ -87,20 +87,13 @@ fn gen_method_impl(sig: &FnSignature, internals_ident: &Ident) -> syn::Result<To
     }
     let params = sig.params();
     let buf_ident = Ident::new("uniffi_args_buf", Span::call_site());
-    let mut write_exprs = sig.write_exprs(&buf_ident).peekable();
-
-    let construct_args_buf = if write_exprs.peek().is_some() {
-        quote! {
-            let mut #buf_ident = ::std::vec::Vec::new();
-            #(#write_exprs;)*
-        }
-    } else {
-        quote! { let #buf_ident = ::std::vec::Vec::new(); }
-    };
+    let mut write_exprs = sig.write_exprs(&buf_ident);
 
     Ok(quote! {
         fn #ident(&self, #(#params),*) -> #return_ty {
-            #construct_args_buf
+            #[allow(unused_mut)]
+            let mut #buf_ident = ::std::vec::Vec::new();
+            #(#write_exprs;)*
             let uniffi_args_rbuf = uniffi::RustBuffer::from_vec(#buf_ident);
 
             #internals_ident.invoke_callback::<#return_ty, crate::UniFfiTag>(self.handle, #index, uniffi_args_rbuf)