chore: add vendor dependencies for kauma build

vendor/syn/tests/test_token_trees.rs

@@ -0,0 +1,32 @@
+#![allow(clippy::uninlined_format_args)]
+
+#[macro_use]
+mod macros;
+
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::Lit;
+
+#[test]
+fn test_struct() {
+    let input = "
+        #[derive(Debug, Clone)]
+        pub struct Item {
+            pub ident: Ident,
+            pub attrs: Vec<Attribute>,
+        }
+    ";
+
+    snapshot!(input as TokenStream, @r###"
+    TokenStream(
+        `# [derive (Debug , Clone)] pub struct Item { pub ident : Ident , pub attrs : Vec < Attribute >, }`,
+    )
+    "###);
+}
+
+#[test]
+fn test_literal_mangling() {
+    let code = "0_4";
+    let parsed: Lit = syn::parse_str(code).unwrap();
+    assert_eq!(code, quote!(#parsed).to_string());
+}