您可以使用build.rs基于构建时存在的文件生成模块。
像这样的东西

let years_path = path::Path::new("./src/years");
let mut mod_file = fs::File::create(years_path.join("mod.rs")).unwrap();

let paths = fs::read_dir(years_path).unwrap();

for entry in paths {
    let entry = entry.unwrap();
    if entry.metadata().unwrap().is_dir() {
        writeln!(
            mod_file,
            "mod {};",
            entry.path().file_name().unwrap().to_str().unwrap()
        )
        .unwrap();
    }
}

我使用的build.rs版本与@pidgeonhands版本非常相似，它对文件夹中的奇怪文件更具弹性（只有在无法创建或写入文件时才会崩溃），并且可以工作多年：

use std::{
    error::Error,
    ffi::OsString,
    fs::{self, File},
    io::Write,
    path::Path,
};

fn main() -> Result<(), Box<dyn Error>> {
    println!("cargo:rerun-if-changed=src/years");
    let years_path = Path::new("src/years");
    let mut years_mod_file = File::create(years_path.join("mod.rs"))?;
    for year in fs::read_dir("src/years")? {
        let Ok(year) = year else {continue};
        let year_name = year.file_name();
        let Some(year_name) = year_name.to_str() else {continue};
        if year_name != OsString::from("mod.rs") {
            writeln!(years_mod_file, "pub mod {year_name};")?;
            let mut year_mod_file = File::create(year.path().join("mod.rs"))?;

            for day in fs::read_dir(year.path())? {
                let Ok(day) = day else {continue};
                if day.file_name() != OsString::from("mod.rs") {
                    let day_name = day.path();
                    let Some(day_name) = day_name.file_stem() else {continue};
                    let Some(day_name) = day_name.to_str() else {continue};
                    writeln!(year_mod_file, "pub mod {day_name};")?;
                    println!("{:?}", day_name);
                }
            }
        }
    }
    Ok(())
}