clippy-driver: pass all args after "--rustc" to rustc

Author: matthiaskrgr

src/driver.rs

@@ -299,6 +299,15 @@ pub fn main() {
         rustc_driver::catch_fatal_errors(move || {
             let mut orig_args: Vec<String> = env::args().collect();
 
+            // make "clippy-driver --rustc" work like a subcommand that passes further args to "rustc"
+            // for example `clippy-driver --rustc --version` will print the rustc version that clippy-driver
+            // uses
+            if let Some(pos) = orig_args.iter().position(|arg| arg == "--rustc") {
+                orig_args.remove(pos);
+                orig_args[0] = "rustc".to_string();
+                return rustc_driver::run_compiler(&orig_args, &mut DefaultCallbacks, None, None);
+            }
+
             if orig_args.iter().any(|a| a == "--version" || a == "-V") {
                 let version_info = rustc_tools_util::get_version_info!();
                 println!("{}", version_info);