Merge pull request #1144 from dtolnay/nothingtraits

Implement extra-traits for syn::parse::Nothing

src/parse.rs

@@ -199,6 +199,8 @@ use crate::token::Token;
 use proc_macro2::{self, Delimiter, Group, Literal, Punct, Span, TokenStream, TokenTree};
 use std::cell::Cell;
 use std::fmt::{self, Debug, Display};
+#[cfg(feature = "extra-traits")]
+use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem;
 use std::ops::Deref;
@@ -1285,3 +1287,29 @@ impl Parse for Nothing {
         Ok(Nothing)
     }
 }
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for Nothing {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("Nothing")
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for Nothing {}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for Nothing {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for Nothing {
+    fn hash<H: Hasher>(&self, _state: &mut H) {}
+}