perf: improve code generation performance

Use `BufWriter` and avoid formatting generated code for faster build
times

Cargo.toml

@@ -68,6 +68,7 @@ heapless = "0.7"
     "common",
 ]
 
+"format-generated-code" = []
 "emit-description" = []
 "emit-extensions" = []
 "std" = ["byteorder/std"]
@@ -81,4 +82,4 @@ default= ["std", "tcp", "udp", "direct-serial", "serial", "serde", "ardupilotmeg
 # build with all features on docs.rs so that users viewing documentation
 # can see everything
 [package.metadata.docs.rs]
-features = ["default", "all-dialects", "emit-description", "emit-extensions"]
+features = ["default", "all-dialects", "emit-description", "emit-extensions", "format-generated-code"]

build/main.rs

@@ -8,6 +8,7 @@ use crate::util::to_module_name;
 use std::env;
 use std::ffi::OsStr;
 use std::fs::{read_dir, File};
+use std::io::BufWriter;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
@@ -63,15 +64,15 @@ pub fn main() {
         modules.push(module_name);
 
         let dest_path = Path::new(&out_dir).join(definition_rs);
-        let mut outf = File::create(&dest_path).unwrap();
+        let mut outf = BufWriter::new(File::create(&dest_path).unwrap());
 
         // generate code
         parser::generate(
             &definitions_dir,
             &definition_file.into_string().unwrap(),
             &mut outf,
         );
-        format_code(&out_dir, &dest_path);
+        dbg_format_code(&out_dir, &dest_path);
 
         // Re-run build if definition file changes
         println!("cargo:rerun-if-changed={}", entry.path().to_string_lossy());
@@ -84,12 +85,17 @@ pub fn main() {
 
         // generate code
         binder::generate(modules, &mut outf);
-        format_code(out_dir, dest_path);
+        dbg_format_code(out_dir, dest_path);
     }
 }
 
-fn format_code(cwd: impl AsRef<Path>, path: impl AsRef<OsStr>) {
+#[cfg(feature = "format-generated-code")]
+fn dbg_format_code(cwd: impl AsRef<Path>, path: impl AsRef<OsStr>) {
     if let Err(error) = Command::new("rustfmt").arg(path).current_dir(cwd).status() {
         eprintln!("{error}");
     }
 }
+
+// Does nothing
+#[cfg(not(feature = "format-generated-code"))]
+fn dbg_format_code(_: impl AsRef<Path>, _: impl AsRef<OsStr>) {}