Fix an uncoming Clippy lint

This lint isn't an issue on our pinned nightly, but it is on more
recent nightlies as of this writing. Might as well fix it now.

Author: joshlf

zerocopy-derive/src/lib.rs

@@ -12,7 +12,7 @@
 // our MSRV.
 #![allow(unknown_lints)]
 #![deny(renamed_and_removed_lints)]
-#![deny(clippy::all, clippy::missing_safety_doc)]
+#![deny(clippy::all, clippy::missing_safety_doc, clippy::undocumented_unsafe_blocks)]
 #![deny(
     rustdoc::bare_urls,
     rustdoc::broken_intra_doc_links,

zerocopy-derive/src/repr.rs

@@ -73,9 +73,7 @@ impl<R: KindRepr> Config<R> {
         }
 
         let initial_sp = metas[0].span();
-        let err_span = metas.iter().skip(1).fold(Some(initial_sp), |sp_option, meta| {
-            sp_option.and_then(|sp| sp.join(meta.span()))
-        });
+        let err_span = metas.iter().skip(1).try_fold(initial_sp, |sp, meta| sp.join(meta.span()));
 
         if self.allowed_combinations.contains(&reprs.as_slice()) {
             Ok(reprs)