fix -vV under the shim

Author: jyn514

src/bootstrap/src/bin/rustc.rs

@@ -83,7 +83,11 @@ fn main() {
             args.remove(0)
         }
     } else {
-        args.remove(0);
+        // Cargo doesn't respect RUSTC_WRAPPER for version information >:(
+        // don't remove the first arg if we're being run as RUSTC instead of RUSTC_WRAPPER.
+        if args[0] == env::current_exe().expect("couldn't get path to rustc shim") {
+            args.remove(0);
+        }
         rustc_real
     };
 

src/bootstrap/src/core/builder.rs

@@ -1643,6 +1643,8 @@ impl<'a> Builder<'a> {
         // NOTE: we intentionally use RUSTC_WRAPPER so that we can support clippy - RUSTC is not
         // respected by clippy-driver; RUSTC_WRAPPER happens earlier, before clippy runs.
         cargo.env("RUSTC_WRAPPER", self.bootstrap_out.join("rustc"));
+        // NOTE: we also need to set RUSTC so cargo can run `rustc -vV`; apparently that ignores RUSTC_WRAPPER >:(
+        cargo.env("RUSTC", self.bootstrap_out.join("rustc"));
 
         // Someone might have set some previous rustc wrapper (e.g.
         // sccache) before bootstrap overrode it. Respect that variable.