Replace std imports with core

pod/src/bytemuck.rs

@@ -4,7 +4,7 @@ use {bytemuck::Pod, solana_program_error::ProgramError};
 
 /// On-chain size of a `Pod` type
 pub const fn pod_get_packed_len<T: Pod>() -> usize {
-    std::mem::size_of::<T>()
+    core::mem::size_of::<T>()
 }
 
 /// Convert a `Pod` into a slice of bytes (zero copy)

pod/src/error.rs

@@ -1,7 +1,7 @@
 //! Error types
 use {
+    core::num::TryFromIntError,
     solana_program_error::{ProgramError, ToStr},
-    std::num::TryFromIntError,
 };
 
 /// Errors that may be returned by the spl-pod library.

pod/src/list/list_trait.rs

@@ -1,8 +1,8 @@
 use {
     crate::{list::ListView, pod_length::PodLength},
     bytemuck::Pod,
+    core::ops::Deref,
     solana_program_error::ProgramError,
-    std::ops::Deref,
 };
 
 /// A trait to abstract the shared, read-only behavior

pod/src/list/list_view.rs

@@ -11,12 +11,12 @@ use {
         primitives::PodU32,
     },
     bytemuck::Pod,
-    solana_program_error::ProgramError,
-    std::{
+    core::{
         marker::PhantomData,
         mem::{align_of, size_of},
         ops::Range,
     },
+    solana_program_error::ProgramError,
 };
 
 /// An API for interpreting a raw buffer (`&[u8]`) as a variable-length collection of Pod elements.

pod/src/list/list_view_mut.rs

@@ -5,8 +5,8 @@ use {
         error::PodSliceError, list::list_trait::List, pod_length::PodLength, primitives::PodU32,
     },
     bytemuck::Pod,
+    core::ops::{Deref, DerefMut},
     solana_program_error::ProgramError,
-    std::ops::{Deref, DerefMut},
 };
 
 #[derive(Debug)]

pod/src/list/list_view_read_only.rs

@@ -3,7 +3,7 @@
 use {
     crate::{list::list_trait::List, pod_length::PodLength, primitives::PodU32},
     bytemuck::Pod,
-    std::ops::Deref,
+    core::ops::Deref,
 };
 
 #[derive(Debug)]
@@ -41,7 +41,7 @@ mod tests {
             primitives::{PodU32, PodU64},
         },
         bytemuck_derive::{Pod as DerivePod, Zeroable},
-        std::mem::size_of,
+        core::mem::size_of,
     };
 
     #[repr(C, align(16))]

pod/src/optional_keys.rs

@@ -10,9 +10,9 @@ use {
 };
 #[cfg(feature = "serde-traits")]
 use {
+    core::{convert::TryFrom, fmt, str::FromStr},
     serde::de::{Error, Unexpected, Visitor},
     serde::{Deserialize, Deserializer, Serialize, Serializer},
-    std::{convert::TryFrom, fmt, str::FromStr},
 };
 
 /// A Pubkey that encodes `None` as all `0`, meant to be usable as a `Pod` type,
@@ -293,7 +293,7 @@ mod tests {
     // `solana-zk-sdk` 2.1.
     fn elgamal_pubkey_from_bytes(bytes: &[u8]) -> PodElGamalPubkey {
         let string = BASE64_STANDARD.encode(bytes);
-        std::str::FromStr::from_str(&string).unwrap()
+        core::str::FromStr::from_str(&string).unwrap()
     }
 
     #[test]

pod/src/primitives.rs

@@ -297,7 +297,7 @@ mod tests {
         #[test_case(PodU128::from_primitive(u128::MAX))]
         fn wincode_roundtrip<
             T: PartialEq
-                + std::fmt::Debug
+                + core::fmt::Debug
                 + for<'de> wincode::SchemaRead<'de, wincode::config::DefaultConfig, Dst = T>
                 + wincode::SchemaWrite<wincode::config::DefaultConfig, Src = T>,
         >(

pod/src/slice.rs

@@ -95,7 +95,7 @@ mod tests {
         test_pubkey: [u8; 32],
     }
 
-    const LENGTH_SIZE: usize = std::mem::size_of::<PodU32>();
+    const LENGTH_SIZE: usize = core::mem::size_of::<PodU32>();
 
     #[test]
     fn test_pod_slice() {
@@ -128,7 +128,7 @@ mod tests {
     fn test_pod_slice_buffer_too_large() {
         // Length is 1. We pass one test struct with 6 trailing bytes to
         // trigger BufferTooLarge.
-        let data_len = LENGTH_SIZE + std::mem::size_of::<TestStruct>() + 6;
+        let data_len = LENGTH_SIZE + core::mem::size_of::<TestStruct>() + 6;
         let mut pod_slice_bytes = vec![1; data_len];
         pod_slice_bytes[0..4].copy_from_slice(&[1, 0, 0, 0]);
         let err = PodSlice::<TestStruct>::unpack(&pod_slice_bytes)