Fix review comments

compiler/rustc_error_messages/src/lib.rs

@@ -21,6 +21,7 @@ use intl_memoizer::concurrent::IntlLangMemoizer;
 use rustc_data_structures::sync::IntoDynSyncSend;
 use rustc_macros::{Decodable, Encodable};
 use rustc_span::Span;
+use smallvec::SmallVec;
 use tracing::{instrument, trace};
 pub use unic_langid::{LanguageIdentifier, langid};
 
@@ -106,8 +107,7 @@ impl From<Vec<FluentError>> for TranslationBundleError {
 /// (overriding any conflicting messages).
 #[instrument(level = "trace")]
 pub fn fluent_bundle(
-    sysroot: PathBuf,
-    default_sysroot: PathBuf,
+    sysroot_candidates: SmallVec<[PathBuf; 2]>,
     requested_locale: Option<LanguageIdentifier>,
     additional_ftl_path: Option<&Path>,
     with_directionality_markers: bool,
@@ -141,7 +141,7 @@ pub fn fluent_bundle(
     // If the user requests the default locale then don't try to load anything.
     if let Some(requested_locale) = requested_locale {
         let mut found_resources = false;
-        for mut sysroot in [sysroot, default_sysroot] {
+        for mut sysroot in sysroot_candidates {
             sysroot.push("share");
             sysroot.push("locale");
             sysroot.push(requested_locale.to_string());