cfg: replace std feature gate alloc imports with extern crate alloc (#10861)

crates/storage/errors/src/db.rs

@@ -1,14 +1,9 @@
-#[cfg(feature = "std")]
-use std::{fmt, fmt::Display, str::FromStr, string::String};
-
-#[cfg(not(feature = "std"))]
 use alloc::{
     boxed::Box,
     format,
     string::{String, ToString},
     vec::Vec,
 };
-#[cfg(not(feature = "std"))]
 use core::{
     fmt,
     fmt::{Debug, Display},

crates/storage/errors/src/lib.rs

@@ -9,7 +9,6 @@
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 #![cfg_attr(not(feature = "std"), no_std)]
 
-#[cfg(not(feature = "std"))]
 extern crate alloc;
 
 /// Database error

crates/storage/errors/src/lockfile.rs

@@ -1,7 +1,5 @@
-use reth_fs_util::FsPathError;
-
-#[cfg(not(feature = "std"))]
 use alloc::string::{String, ToString};
+use reth_fs_util::FsPathError;
 
 /// Storage lock error.
 #[derive(Debug, Clone, PartialEq, Eq, derive_more::Display)]

crates/storage/errors/src/provider.rs

@@ -6,7 +6,6 @@ use reth_primitives::{BlockHashOrNumber, GotExpected, StaticFileSegment, TxHashO
 #[cfg(feature = "std")]
 use std::path::PathBuf;
 
-#[cfg(not(feature = "std"))]
 use alloc::{boxed::Box, string::String};
 
 /// Provider result type.