Make some Clippy lints more strict

Once #61 is done, we'll forbid the `missing_safety_docs` and
`undocumented_unsafe_blocks` Clippy lints to the root module. Until
that happens, we forbid them as high in the module tree as possible.

src/byteorder.rs

@@ -61,6 +61,8 @@
 //! }
 //! ```
 
+#![forbid(clippy::missing_safety_doc, clippy::undocumented_unsafe_blocks)]
+
 use core::{
     convert::{TryFrom, TryInto},
     fmt::{self, Binary, Debug, Display, Formatter, LowerHex, Octal, UpperHex},

src/derive_util.rs

@@ -12,6 +12,7 @@
 //! different times).
 
 #![allow(missing_debug_implementations)]
+#![forbid(clippy::missing_safety_doc, clippy::undocumented_unsafe_blocks)]
 
 use core::marker::PhantomData;
 

src/lib.rs

@@ -1111,6 +1111,8 @@ safety_comment! {
 // [2] https://github.com/rust-lang/unsafe-code-guidelines/issues/38
 #[cfg(feature = "simd")]
 mod simd {
+    #![forbid(clippy::missing_safety_doc, clippy::undocumented_unsafe_blocks)]
+
     /// Defines a module which implements `FromZeroes`, `FromBytes`, and
     /// `AsBytes` for a set of types from a module in `core::arch`.
     ///
@@ -2786,6 +2788,8 @@ unsafe impl<'a> ByteSliceMut for RefMut<'a, [u8]> {}
 
 #[cfg(feature = "alloc")]
 mod alloc_support {
+    #![forbid(clippy::missing_safety_doc, clippy::undocumented_unsafe_blocks)]
+
     use alloc::vec::Vec;
 
     use super::*;

zerocopy-derive/src/lib.rs

@@ -12,7 +12,8 @@
 // our MSRV.
 #![allow(unknown_lints)]
 #![deny(renamed_and_removed_lints)]
-#![deny(clippy::all, clippy::missing_safety_doc)]
+#![deny(clippy::all)]
+#![forbid(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)