Vendor things

third-party/vendor/swc_config_macro/src/lib.rs

@@ -0,0 +1,10 @@
+extern crate proc_macro;
+
+mod merge;
+
+#[proc_macro_derive(Merge)]
+pub fn derive_merge(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let input = syn::parse(input).expect("failed to parse input as DeriveInput");
+
+    self::merge::expand(input).into()
+}