Avoid hashing arg names in hash of function signature
diff --git a/syntax/impls.rs b/syntax/impls.rs
index fd8162f..8762652 100644
--- a/syntax/impls.rs
+++ b/syntax/impls.rs
@@ -296,7 +296,23 @@
             && ret == ret2
             && throws == throws2
             && args.len() == args2.len()
-            && args.iter().zip(args2).all(|(arg, arg2)| arg == arg2)
+            && args.iter().zip(args2).all(|(arg, arg2)| {
+                let Var {
+                    doc: _,
+                    attrs: _,
+                    visibility: _,
+                    ident: _,
+                    ty,
+                } = arg;
+                let Var {
+                    doc: _,
+                    attrs: _,
+                    visibility: _,
+                    ident: _,
+                    ty: ty2,
+                } = arg2;
+                ty == ty2
+            })
     }
 }
 
@@ -316,49 +332,20 @@
         unsafety.is_some().hash(state);
         receiver.hash(state);
         for arg in args {
-            arg.hash(state);
+            let Var {
+                doc: _,
+                attrs: _,
+                visibility: _,
+                ident: _,
+                ty,
+            } = arg;
+            ty.hash(state);
         }
         ret.hash(state);
         throws.hash(state);
     }
 }
 
-impl Eq for Var {}
-
-impl PartialEq for Var {
-    fn eq(&self, other: &Var) -> bool {
-        let Var {
-            doc: _,
-            attrs: _,
-            visibility: _,
-            ident,
-            ty,
-        } = self;
-        let Var {
-            doc: _,
-            attrs: _,
-            visibility: _,
-            ident: ident2,
-            ty: ty2,
-        } = other;
-        ident == ident2 && ty == ty2
-    }
-}
-
-impl Hash for Var {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        let Var {
-            doc: _,
-            attrs: _,
-            visibility: _,
-            ident,
-            ty,
-        } = self;
-        ident.hash(state);
-        ty.hash(state);
-    }
-}
-
 impl Eq for Receiver {}
 
 impl PartialEq for Receiver {