Migrate ff_derive to proc-macro2 1.0

ff_derive/Cargo.toml

@@ -16,6 +16,6 @@ proc-macro = true
 num-bigint = "0.2"
 num-traits = "0.2"
 num-integer = "0.1"
-proc-macro2 = "0.4"
-quote = "0.6"
-syn = "0.14"
+proc-macro2 = "1"
+quote = "1"
+syn = "1"

ff_derive/src/lib.rs

@@ -91,10 +91,10 @@ fn fetch_wrapped_ident(body: &syn::Data) -> Option<syn::Ident> {
 /// Fetch an attribute string from the derived struct.
 fn fetch_attr(name: &str, attrs: &[syn::Attribute]) -> Option<String> {
     for attr in attrs {
-        if let Some(meta) = attr.interpret_meta() {
+        if let Ok(meta) = attr.parse_meta() {
             match meta {
                 syn::Meta::NameValue(nv) => {
-                    if nv.ident.to_string() == name {
+                    if nv.path.get_ident().map(|i| i.to_string()) == Some(name.to_string()) {
                         match nv.lit {
                             syn::Lit::Str(ref s) => return Some(s.value()),
                             _ => {