Meaningful changes from aggressive-clippy

I do want to enable a few specific lints, yet aggressive-clippy as a whole
isn't worthwhile.

common/db/src/lib.rs

@@ -23,7 +23,7 @@ pub trait Db: 'static + Send + Sync + Clone + Debug + Get {
   fn key(db_dst: &'static [u8], item_dst: &'static [u8], key: impl AsRef<[u8]>) -> Vec<u8> {
     let db_len = u8::try_from(db_dst.len()).unwrap();
     let dst_len = u8::try_from(item_dst.len()).unwrap();
-    [[db_len].as_ref(), db_dst, [dst_len].as_ref(), item_dst, key.as_ref()].concat().to_vec()
+    [[db_len].as_ref(), db_dst, [dst_len].as_ref(), item_dst, key.as_ref()].concat()
   }
   fn txn(&mut self) -> Self::Transaction<'_>;
 }
@@ -38,7 +38,11 @@ impl<'a> Get for MemDbTxn<'a> {
     if self.2.contains(key.as_ref()) {
       return None;
     }
-    self.1.get(key.as_ref()).cloned().or(self.0 .0.read().unwrap().get(key.as_ref()).cloned())
+    self
+      .1
+      .get(key.as_ref())
+      .cloned()
+      .or_else(|| self.0 .0.read().unwrap().get(key.as_ref()).cloned())
   }
 }
 impl<'a> DbTxn for MemDbTxn<'a> {

common/std-shims/src/io.rs

@@ -53,10 +53,7 @@ mod shims {
 
   impl Read for &[u8] {
     fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
-      let mut read = buf.len();
-      if self.len() < buf.len() {
-        read = self.len();
-      }
+      let read = buf.len().min(self.len());
       buf[.. read].copy_from_slice(&self[.. read]);
       *self = &self[read ..];
       Ok(read)

common/std-shims/src/lib.rs

@@ -2,33 +2,12 @@
 #![doc = include_str!("../README.md")]
 #![cfg_attr(not(feature = "std"), no_std)]
 
-#[cfg(not(feature = "std"))]
-#[allow(unused_imports)]
-#[doc(hidden)]
-#[macro_use]
 pub extern crate alloc;
 
 pub mod sync;
 pub mod collections;
 pub mod io;
 
-pub mod vec {
-  #[cfg(not(feature = "std"))]
-  pub use alloc::vec::*;
-  #[cfg(feature = "std")]
-  pub use std::vec::*;
-}
-
-pub mod str {
-  #[cfg(not(feature = "std"))]
-  pub use alloc::str::*;
-  #[cfg(feature = "std")]
-  pub use std::str::*;
-}
-
-pub mod string {
-  #[cfg(not(feature = "std"))]
-  pub use alloc::string::*;
-  #[cfg(feature = "std")]
-  pub use std::string::*;
-}
+pub use alloc::vec;
+pub use alloc::str;
+pub use alloc::string;

common/std-shims/src/sync.rs

@@ -1,4 +1,5 @@
 pub use core::sync::*;
+pub use alloc::sync::*;
 
 mod mutex_shim {
   #[cfg(feature = "std")]
@@ -57,7 +58,7 @@ mod oncelock_shim {
       let mut lock = self.0.lock();
       if !*lock {
         unsafe {
-          (core::ptr::addr_of!(self.1) as *mut Option<_>).write_unaligned(Some(f()));
+          core::ptr::addr_of!(self.1).cast_mut().write_unaligned(Some(f()));
         }
       }
       *lock = true;