third_party_rust_bindgen/bindgen/deps.rs

/// Generating build depfiles from parsed bindings.
use std::{collections::BTreeSet, path::PathBuf};

#[derive(Clone, Debug)]
pub(crate) struct DepfileSpec {
    pub output_module: String,
    pub depfile_path: PathBuf,
}

impl DepfileSpec {
    pub fn write(&self, deps: &BTreeSet<String>) -> std::io::Result<()> {
        let mut buf = format!("{}:", self.output_module);

        for file in deps {
            buf = format!("{} {}", buf, file);
        }

        std::fs::write(&self.depfile_path, &buf)
    }
}