feat: compile time optimization (#775)

crates/router/src/build.rs

@@ -4,5 +4,6 @@ fn main() {
     #[cfg(debug_assertions)]
     println!("cargo:rustc-env=RUST_MIN_STACK=4194304"); // 4 * 1024 * 1024 = 4 MiB
 
+    #[cfg(feature = "vergen")]
     router_env::vergen::generate_cargo_instructions();
 }

crates/router/src/configs/settings.rs

@@ -16,7 +16,7 @@ use crate::{
 };
 
 #[derive(clap::Parser, Default)]
-#[command(version = router_env::version!())]
+#[cfg_attr(feature = "vergen", command(version = router_env::version!()))]
 pub struct CmdLineConf {
     /// Config file.
     /// Application will look for "config/config.toml" if this option isn't specified.