use the build triple for deciding whether the first argument is clippy or not

previously we had false-negatives when cross-compiling, which meant people just wouldn't get clippy lints for targets other than the host

Author: jyn514

src/bootstrap/src/bin/rustc.rs

@@ -66,10 +66,9 @@ fn main() {
     // otherwise, substitute whatever cargo thinks rustc should be with RUSTC_REAL.
     // NOTE: this means we ignore RUSTC in the environment.
     // FIXME: We might want to consider removing RUSTC_REAL and setting RUSTC directly?
-    let target_name = target
-        .map(|s| s.to_owned())
-        .unwrap_or_else(|| env::var("CFG_COMPILER_HOST_TRIPLE").unwrap());
-    let is_clippy = args[0].to_string_lossy().ends_with(&exe("clippy-driver", &target_name));
+    // NOTE: we intentionally pass the name of the host, not the target.
+    let host = env::var("CFG_COMPILER_BUILD_TRIPLE").unwrap();
+    let is_clippy = args[0].to_string_lossy().ends_with(&exe("clippy-driver", &host));
     let rustc_driver = if is_clippy {
         if is_build_script {
             // Don't run clippy on build scripts (for one thing, we may not have libstd built with
@@ -85,8 +84,6 @@ fn main() {
         // 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");
-        // NOTE: we intentionally pass the name of the host, not the target.
-        let host = env::var("CFG_COMPILER_BUILD_TRIPLE").unwrap();
         let arg0 = exe(args[0].to_str().expect("only utf8 paths are supported"), &host);
         if Path::new(&arg0) == current_exe {
             args.remove(0);