Rustc shim is now a wrapper

src/bootstrap/Cargo.toml

@@ -29,6 +29,11 @@ name = "sccache-plus-cl"
 path = "bin/sccache-plus-cl.rs"
 test = false
 
+[[bin]]
+name = "rustc-shim"
+path = "bin/rustc-shim.rs"
+test = false
+
 [dependencies]
 is-terminal = "0.4"
 build_helper = { path = "../tools/build_helper" }

src/bootstrap/bin/rustc-shim.rs

@@ -0,0 +1,10 @@
+fn main() {
+    if std::env::args().any(|v| v == "-vV") {
+        std::process::Command::new(std::env::var("RUSTC_REAL").unwrap())
+            .arg("-vV")
+            .status()
+            .unwrap();
+    } else {
+        todo!("rustc-shim")
+    }
+}

src/bootstrap/bin/rustc.rs

@@ -1,4 +1,4 @@
-//! Shim which is passed to Cargo as "rustc" when running the bootstrap.
+//! Shim which is passed to Cargo as "RUSTC_WRAPPER" when running the bootstrap.
 //!
 //! This shim will take care of some various tasks that our build process
 //! requires that Cargo can't quite do through normal configuration:
@@ -24,7 +24,12 @@ use std::str::FromStr;
 use std::time::Instant;
 
 fn main() {
-    let args = env::args_os().skip(1).collect::<Vec<_>>();
+    let mut args = env::args_os().skip(1).collect::<Vec<_>>();
+
+    let _compiler = args.remove(0);
+
+    let args = args;
+
     let arg = |name| args.windows(2).find(|args| args[0] == name).and_then(|args| args[1].to_str());
 
     // Detect whether or not we're a build script depending on whether --target

src/bootstrap/builder.rs

@@ -1581,7 +1581,8 @@ impl<'a> Builder<'a> {
         // Clippy support is a hack and uses the default `cargo-clippy` in path.
         // Don't override RUSTC so that the `cargo-clippy` in path will be run.
         if cmd != "clippy" {
-            cargo.env("RUSTC", self.bootstrap_out.join("rustc"));
+            cargo.env("RUSTC", self.bootstrap_out.join("rustc-shim"));
+            cargo.env("RUSTC_WRAPPER", self.bootstrap_out.join("rustc"));
         }
 
         // Dealing with rpath here is a little special, so let's go into some

src/bootstrap/test.rs

@@ -315,7 +315,8 @@ impl Step for Cargotest {
             cmd.arg(&cargo)
                 .arg(&out_dir)
                 .args(builder.config.cmd.test_args())
-                .env("RUSTC", builder.rustc(compiler))
+                .env("RUSTC", builder.bootstrap_out.join("rustc-shim"))
+                .env("RUSTC_WRAPPER", builder.rustc(compiler))
                 .env("RUSTDOC", builder.rustdoc(compiler)),
         );
     }
@@ -1094,7 +1095,8 @@ impl Step for RustdocGUI {
                     .arg(&out_dir)
                     .env("RUSTC_BOOTSTRAP", "1")
                     .env("RUSTDOC", builder.rustdoc(self.compiler))
-                    .env("RUSTC", builder.rustc(self.compiler))
+                    .env("RUSTC", builder.bootstrap_out.join("rustc-shim"))
+                    .env("RUSTC_WRAPPER", builder.rustc(self.compiler))
                     .current_dir(path);
                 // FIXME: implement a `// compile-flags` command or similar
                 //        instead of hard-coding this test
@@ -2796,7 +2798,8 @@ impl Step for RustInstaller {
         cmd.current_dir(&tmpdir);
         cmd.env("CARGO_TARGET_DIR", tmpdir.join("cargo-target"));
         cmd.env("CARGO", &builder.initial_cargo);
-        cmd.env("RUSTC", &builder.initial_rustc);
+        cmd.env("RUSTC", &builder.bootstrap_out.join("rustc-shim"));
+        cmd.env("RUSTC_WRAPPER", &builder.initial_rustc);
         cmd.env("TMP_DIR", &tmpdir);
         try_run(builder, &mut cmd);
     }