Use clap to generate shell completions

build.rs

@@ -0,0 +1,31 @@
+use std::fs;
+
+use clap::Shell;
+
+include!("src/hyperfine/app.rs");
+
+fn main() {
+    let min_version = "1.39";
+
+    match version_check::is_min_version(min_version) {
+        Some(true) => {}
+        // rustc version too small or can't figure it out
+        _ => {
+            eprintln!("'hyperfine' requires rustc >= {}", min_version);
+            std::process::exit(1);
+        }
+    }
+
+    let var = std::env::var_os("SHELL_COMPLETIONS_DIR").or(std::env::var_os("OUT_DIR"));
+    let outdir = match var {
+        None => return,
+        Some(outdir) => outdir,
+    };
+    fs::create_dir_all(&outdir).unwrap();
+
+    let mut app = build_app();
+    app.gen_completions("hyperfine", Shell::Bash, &outdir);
+    app.gen_completions("hyperfine", Shell::Fish, &outdir);
+    app.gen_completions("hyperfine", Shell::Zsh, &outdir);
+    app.gen_completions("hyperfine", Shell::PowerShell, &outdir);
+}