Fix Clippy benchmarks

collector/src/bin/collector.rs

@@ -382,7 +382,8 @@ struct CompileTimeOptions {
     #[arg(long)]
     rustdoc: Option<PathBuf>,
 
-    /// The path to the local clippy to measure
+    /// The path to the local clippy to measure.
+    /// It should be a path to the `clippy-driver` binary.
     #[arg(long)]
     clippy: Option<PathBuf>,
 }

collector/src/compile/execute/mod.rs

@@ -248,7 +248,7 @@ impl<'a> CargoProcess<'a> {
         };
 
         if let Some(c) = &self.toolchain.components.clippy {
-            cmd.env("CLIPPY", &*FAKE_CLIPPY).env("CLIPPY_REAL", c);
+            cmd.env("CLIPPY_REAL", c);
         }
 
         for config in &self.toolchain.components.cargo_configs {
@@ -335,7 +335,12 @@ impl<'a> CargoProcess<'a> {
                 }
                 Profile::Debug => {}
                 Profile::Doc => {}
-                Profile::Clippy => {}
+                Profile::Clippy => {
+                    cmd.arg("--profile").arg("check");
+                    // For Clippy, we still invoke `cargo rustc`, but we need to override the
+                    // executed rustc to be clippy-fake.
+                    cmd.env("RUSTC", &*FAKE_CLIPPY);
+                }
                 Profile::Opt => {
                     cmd.arg("--release");
                 }

collector/src/toolchain.rs

@@ -128,7 +128,7 @@ impl SysrootDownload {
         let components = ToolchainComponents::from_binaries_and_libdir(
             sysroot_bin("rustc")?,
             Some(sysroot_bin("rustdoc")?),
-            sysroot_bin("cargo-clippy").ok(),
+            sysroot_bin("clippy-driver").ok(),
             sysroot_bin("cargo")?,
             &self.directory.join(&self.rust_sha).join("lib"),
         )?;
@@ -484,12 +484,12 @@ pub fn get_local_toolchain(
         )
     } else if profiles.contains(&Profile::Clippy) {
         // We need a `clippy`. Look for one next to `rustc`.
-        if let Ok(clippy) = rustc.with_file_name("cargo-clippy").canonicalize() {
+        if let Ok(clippy) = rustc.with_file_name("clippy-driver").canonicalize() {
             debug!("found clippy: {:?}", &clippy);
             Some(clippy)
         } else {
             anyhow::bail!(
-                    "'Clippy' build specified but '--cargo-clippy' not specified and no 'cargo-clippy' found \
+                    "'Clippy' build specified but '--clippy' not specified and no 'clippy-driver' found \
                     next to 'rustc'"
                 );
         }