Parse generic params on impl block
diff --git a/syntax/tokens.rs b/syntax/tokens.rs
index 1c7c5bc..dd5be01 100644
--- a/syntax/tokens.rs
+++ b/syntax/tokens.rs
@@ -192,12 +192,14 @@
     fn to_tokens(&self, tokens: &mut TokenStream) {
         let Impl {
             impl_token,
+            generics,
             negative: _,
             ty,
             brace_token,
             negative_token,
         } = self;
         impl_token.to_tokens(tokens);
+        generics.to_tokens(tokens);
         negative_token.to_tokens(tokens);
         ty.to_tokens(tokens);
         brace_token.surround(tokens, |_tokens| {});