Add experiment to produce precompiled builds of serde_derive

precompiled/serde_derive/main.rs

@@ -0,0 +1,22 @@
+extern crate proc_macro2;
+
+use proc_macro2::watt;
+use proc_macro2::watt::buffer::InputBuffer;
+use std::io::{self, Read, Write};
+
+fn main() {
+    let mut buf = Vec::new();
+    io::stdin().read_to_end(&mut buf).unwrap();
+
+    let mut buf = InputBuffer::new(&buf);
+    let derive = match buf.read_u8() {
+        0 => serde_derive::derive_serialize,
+        1 => serde_derive::derive_deserialize,
+        _ => unreachable!(),
+    };
+
+    let input = watt::load(&mut buf);
+    let output = derive(input);
+    let bytes = watt::linearize(output);
+    io::stdout().write_all(&bytes).unwrap();
+}