use rustc_version also to parse host in compiletest

Author: RalfJung

tests/compiletest.rs

@@ -147,12 +147,9 @@ fn get_host() -> String {
         .output()
         .expect("rustc not found for -vV")
         .stdout;
-    let host = std::str::from_utf8(&host).expect("sysroot is not utf8");
-    let host = host.split("\nhost: ").nth(1).expect(
-        "no host: part in rustc -vV",
-    );
-    let host = host.split('\n').next().expect("no \n after host");
-    String::from(host)
+    let host = std::str::from_utf8(&host).expect("host is not utf8");
+    let version_meta = rustc_version::version_meta_for(&host).expect("failed to parse rustc version info");
+    version_meta.host
 }
 
 fn run_pass_miri(opt: bool) {