rewrite build script to actually pick up on changes properly

source/tycho/build.rs

@@ -1,11 +1,36 @@
-use std::process::Command;
+use std::{env, fs, io, path::Path, process::Command};
 
-fn main() -> std::io::Result<()>
+fn io_err(st: &'static str) -> io::Error
 {
-   let out_file = std::env::var("OUT_DIR").unwrap();
+   io::Error::new(io::ErrorKind::Other, st)
+}
+
+fn traverse_dir(path: &Path) -> io::Result<()>
+{
+   for ent in fs::read_dir(path)? {
+      let path = ent?.path();
+
+      if path.is_dir() {
+         traverse_dir(&path)?;
+      } else {
+         if let Some(path) = path.to_str() {
+            println!("cargo:rerun-if-changed={}", path);
+         } else {
+            return Err(io_err("failed to convert path"));
+         }
+      }
+   }
+
+   Ok(())
+}
+
+fn main() -> io::Result<()>
+{
+   let out_file = env::var("OUT_DIR").unwrap();
    let out_file = format!("--target={}/resources", out_file);
 
-   println!("cargo:rerun-if-changed=data");
+   // traverse each file in the data directory, because cargo won't do this
+   traverse_dir(Path::new("data"))?;
 
    let o = Command::new("glib-compile-resources").arg("data/resources.xml")
                                                  .arg(out_file)
@@ -14,7 +39,7 @@ fn main() -> std::io::Result<()>
 
    if !o.status.success() {
       dbg!(o);
-      Err(std::io::Error::new(std::io::ErrorKind::Other, "failed to compile resources"))
+      Err(io_err("failed to compile resources"))
    } else {
       Ok(())
    }