Touch up PR 227

Author: dtolnay

src/expand.rs

@@ -362,11 +362,11 @@ fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
                 quote!(let #mutability #ident = #self_token;)
             }
             FnArg::Typed(arg) => {
-                // If there is a `#[cfg(..)]` attribute that selectively
-                // enables the parameter, forward it to the variable.
+                // If there is a #[cfg(...)] attribute that selectively enables
+                // the parameter, forward it to the variable.
                 //
-                // This is currently not applied to the `self` parameter
-                let attrs = arg.attrs.iter();
+                // This is currently not applied to the `self` parameter.
+                let attrs = arg.attrs.iter().filter(|attr| attr.path.is_ident("cfg"));
 
                 if let Pat::Ident(PatIdent {
                     ident, mutability, ..
@@ -377,24 +377,24 @@ fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
                         let prefixed = Ident::new("__self", ident.span());
                         quote!(let #mutability #prefixed = #ident;)
                     } else {
-                        quote!(
+                        quote! {
                             #(#attrs)*
                             let #mutability #ident = #ident;
-                        )
+                        }
                     }
                 } else {
                     let pat = &arg.pat;
                     let ident = positional_arg(i, pat);
                     if let Pat::Wild(_) = **pat {
-                        quote!(
+                        quote! {
                             #(#attrs)*
                             let #ident = #ident;
-                        )
+                        }
                     } else {
-                        quote!(
+                        quote! {
                             #(#attrs)*
                             let #pat = #ident;
-                        )
+                        }
                     }
                 }
             }