Merge commit '11a0cceab9' into subtree-update_cg_gcc_2023-10-09

compiler/rustc_codegen_gcc/build_system/src/main.rs

@@ -0,0 +1,62 @@
+use std::env;
+use std::process;
+
+mod build;
+mod config;
+mod prepare;
+mod rustc_info;
+mod utils;
+
+macro_rules! arg_error {
+    ($($err:tt)*) => {{
+        eprintln!($($err)*);
+        eprintln!();
+        usage();
+        std::process::exit(1);
+    }};
+}
+
+fn usage() {
+    println!(
+        "\
+Available commands for build_system:
+
+    prepare  : Run prepare command
+    build    : Run build command
+    --help   : Show this message"
+    );
+}
+
+pub enum Command {
+    Prepare,
+    Build,
+}
+
+fn main() {
+    if env::var("RUST_BACKTRACE").is_err() {
+        env::set_var("RUST_BACKTRACE", "1");
+    }
+
+    let command = match env::args().nth(1).as_deref() {
+        Some("prepare") => Command::Prepare,
+        Some("build") => Command::Build,
+        Some("--help") => {
+            usage();
+            process::exit(0);
+        }
+        Some(flag) if flag.starts_with('-') => arg_error!("Expected command found flag {}", flag),
+        Some(command) => arg_error!("Unknown command {}", command),
+        None => {
+            usage();
+            process::exit(0);
+        }
+    };
+
+    if let Err(e) = match command {
+        Command::Prepare => prepare::run(),
+        Command::Build => build::run(),
+    } {
+        eprintln!("Command failed to run: {e:?}");
+        process::exit(1);
+    }
+}