Make host_root return host.root(), not host.dest()

Also create host_dest function to let other callsites retain their old
functionality

Author: khyperia

src/cargo/core/compiler/context/compilation_files.rs

@@ -207,11 +207,16 @@ impl<'a, 'cfg: 'a> CompilationFiles<'a, 'cfg> {
         }
     }
 
-    /// Returns the root of the build output tree for the host
-    pub fn host_root(&self) -> &Path {
+    /// Returns the final artifact path for the host (`/…/target/debug`)
+    pub fn host_dest(&self) -> &Path {
         self.host.dest()
     }
 
+    /// Returns the root of the build output tree for the host (`/…/target`)
+    pub fn host_root(&self) -> &Path {
+        self.host.root()
+    }
+
     /// Returns the host `deps` directory path.
     pub fn host_deps(&self) -> &Path {
         self.host.deps()

src/cargo/core/compiler/custom_build.rs

@@ -272,7 +272,7 @@ fn build_work(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Job> {
     let output_file = script_run_dir.join("output");
     let err_file = script_run_dir.join("stderr");
     let root_output_file = script_run_dir.join("root-output");
-    let host_target_root = cx.files().host_root().to_path_buf();
+    let host_target_root = cx.files().host_dest().to_path_buf();
     let all = (
         id,
         pkg_name.clone(),

src/cargo/core/compiler/mod.rs

@@ -217,7 +217,7 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
     exec.init(cx, unit);
     let exec = exec.clone();
 
-    let root_output = cx.files().host_root().to_path_buf();
+    let root_output = cx.files().host_dest().to_path_buf();
     let target_dir = cx.bcx.ws.target_dir().into_path_unlocked();
     let pkg_root = unit.pkg.root().to_path_buf();
     let cwd = rustc