bootstrap: fully rely on RUSTC_WRAPPER

Author: RalfJung

src/bootstrap/src/bin/rustc.rs

@@ -16,7 +16,7 @@
 //! never get replaced.
 
 use std::env;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 use std::process::{Child, Command};
 use std::time::Instant;
 
@@ -75,17 +75,12 @@ fn main() {
             args.drain(..2);
             rustc_real
         } else {
+            // The first param is the clippy-driver we should call.
             args.remove(0)
         }
     } else {
-        // 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.
-        // Cargo also sometimes doesn't pass the `.exe` suffix on Windows - add it manually.
-        let current_exe = env::current_exe().expect("couldn't get path to rustc shim");
-        let arg0 = exe(args[0].to_str().expect("only utf8 paths are supported"), &host);
-        if Path::new(&arg0) == current_exe {
-            args.remove(0);
-        }
+        // We are RUSTC_WRAPPER; remove the dummy rustc invocation we wrap.
+        args.remove(0);
         rustc_real
     };
 

src/bootstrap/src/core/builder.rs

@@ -1802,8 +1802,8 @@ 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"));
+        // Set RUSTC to a non-existent path: it should never be called, since we always invoke the wrapper!
+        cargo.env("RUSTC", "/path/to/nowhere/all-rustc-calls-should-go-through-the-wrapper");
 
         // Someone might have set some previous rustc wrapper (e.g.
         // sccache) before bootstrap overrode it. Respect that variable.