Fix compat with current nightly

Author: alexcrichton

crates/backend/src/ast.rs

@@ -1,3 +1,4 @@
+use proc_macro2::TokenTree;
 use quote::{ToTokens, Tokens};
 use shared;
 use syn;
@@ -757,7 +758,16 @@ impl BindgenAttrs {
             Some(i) => i,
             None => return BindgenAttrs::default(),
         };
-        syn::parse(attrs.remove(pos).tts.into()).expect("malformed #[wasm_bindgen] attribute")
+        let mut tts = attrs.remove(pos).tts.into_iter();
+        let tt = match tts.next() {
+            Some(TokenTree::Group(d)) => d.stream(),
+            Some(_) => panic!("malformed #[wasm_bindgen] attribute"),
+            None => return BindgenAttrs::default(),
+        };
+        if tts.next().is_some() {
+            panic!("malformed #[wasm_bindgen] attribute");
+        }
+        syn::parse(tt.into()).expect("malformed #[wasm_bindgen] attribute")
     }
 
     fn module(&self) -> Option<&str> {
@@ -859,11 +869,11 @@ impl BindgenAttrs {
 impl syn::synom::Synom for BindgenAttrs {
     named!(parse -> Self, alt!(
         do_parse!(
-            opts: parens!(call!(
+            opts: call!(
                 syn::punctuated::Punctuated::<_, syn::token::Comma>::parse_terminated
-            )) >>
+            ) >>
             (BindgenAttrs {
-                attrs: opts.1.into_iter().collect(),
+                attrs: opts.into_iter().collect(),
             })
         ) => { |s| s }
         |

crates/backend/src/codegen.rs

@@ -109,20 +109,20 @@ impl ToTokens for ast::Struct {
         (quote! {
             impl ::wasm_bindgen::describe::WasmDescribe for #name {
                 fn describe() {
+                    use wasm_bindgen::__wbindgen_if_not_std;
+                    __wbindgen_if_not_std! {
+                        compile_error! {
+                            "exporting a class to JS requires the `std` feature to \
+                             be enabled in the `wasm-bindgen` crate"
+                        }
+                    }
                     use wasm_bindgen::describe::*;
                     inform(RUST_STRUCT);
                     inform(#name_len);
                     #(inform(#name_chars);)*
                 }
             }
 
-            ::wasm_bindgen::__wbindgen_if_not_std! {
-                compile_error! {
-                    "exporting a class to JS requires the `std` feature to \
-                     be enabled in the `wasm-bindgen` crate"
-                }
-            }
-
             impl ::wasm_bindgen::convert::IntoWasmAbi for #name {
                 type Abi = u32;