From 2801eb8da1b7f05e0ef238e844733ea9c6ec1403 Mon Sep 17 00:00:00 2001
From: kevinheavey <heaveykevin2@gmail.com>
Date: Thu, 31 Oct 2024 14:57:34 +0400
Subject: [PATCH 1/7] extract keccak-hasher crate

---
 Cargo.lock                                    | 18 +++++
 Cargo.toml                                    |  2 +
 programs/sbf/Cargo.lock                       | 13 +++
 sdk/keccak-hasher/Cargo.toml                  | 49 ++++++++++++
 .../keccak.rs => keccak-hasher/src/lib.rs}    | 79 ++++++++++---------
 sdk/program/Cargo.toml                        |  1 +
 sdk/program/src/lib.rs                        |  3 +-
 7 files changed, 126 insertions(+), 39 deletions(-)
 create mode 100644 sdk/keccak-hasher/Cargo.toml
 rename sdk/{program/src/keccak.rs => keccak-hasher/src/lib.rs} (61%)

diff --git a/Cargo.lock b/Cargo.lock
index 33543a024ae40a..cd2e2777a412b0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -7196,6 +7196,23 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "solana-keccak-hasher"
+version = "2.2.0"
+dependencies = [
+ "borsh 1.5.3",
+ "bs58",
+ "serde",
+ "serde_derive",
+ "sha3",
+ "solana-atomic-u64",
+ "solana-define-syscall",
+ "solana-frozen-abi",
+ "solana-frozen-abi-macro",
+ "solana-hash",
+ "solana-sanitize",
+]
+
 [[package]]
 name = "solana-keygen"
 version = "2.2.0"
@@ -7742,6 +7759,7 @@ dependencies = [
  "solana-frozen-abi-macro",
  "solana-hash",
  "solana-instruction",
+ "solana-keccak-hasher",
  "solana-last-restart-slot",
  "solana-logger",
  "solana-msg",
diff --git a/Cargo.toml b/Cargo.toml
index 73f1183da72747..1693ffd9c88c73 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -124,6 +124,7 @@ members = [
     "sdk/hash",
     "sdk/inflation",
     "sdk/instruction",
+    "sdk/keccak-hasher",
     "sdk/keypair",
     "sdk/logger",
     "sdk/macro",
@@ -463,6 +464,7 @@ solana-hash = { path = "sdk/hash", version = "=2.2.0", default-features = false
 solana-inflation = { path = "sdk/inflation", version = "=2.2.0" }
 solana-inline-spl = { path = "inline-spl", version = "=2.2.0" }
 solana-instruction = { path = "sdk/instruction", version = "=2.2.0", default-features = false }
+solana-keccak-hasher = { path = "sdk/keccak-hasher", version = "=2.2.0" }
 solana-keypair = { path = "sdk/keypair", version = "=2.2.0" }
 solana-last-restart-slot = { path = "sdk/last-restart-slot", version = "=2.2.0" }
 solana-lattice-hash = { path = "lattice-hash", version = "=2.2.0" }
diff --git a/programs/sbf/Cargo.lock b/programs/sbf/Cargo.lock
index 04379aeb571d24..8d29cb8c9e1af3 100644
--- a/programs/sbf/Cargo.lock
+++ b/programs/sbf/Cargo.lock
@@ -5749,6 +5749,18 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "solana-keccak-hasher"
+version = "2.2.0"
+dependencies = [
+ "bs58",
+ "sha3",
+ "solana-atomic-u64",
+ "solana-define-syscall",
+ "solana-hash",
+ "solana-sanitize",
+]
+
 [[package]]
 name = "solana-keypair"
 version = "2.2.0"
@@ -6095,6 +6107,7 @@ dependencies = [
  "solana-fee-calculator",
  "solana-hash",
  "solana-instruction",
+ "solana-keccak-hasher",
  "solana-last-restart-slot",
  "solana-msg",
  "solana-native-token",
diff --git a/sdk/keccak-hasher/Cargo.toml b/sdk/keccak-hasher/Cargo.toml
new file mode 100644
index 00000000000000..18fa2c11151acc
--- /dev/null
+++ b/sdk/keccak-hasher/Cargo.toml
@@ -0,0 +1,49 @@
+[package]
+name = "solana-keccak-hasher"
+description = "Solana Keccak hashing"
+documentation = "https://docs.rs/solana-keccak-hasher"
+version = { workspace = true }
+authors = { workspace = true }
+repository = { workspace = true }
+homepage = { workspace = true }
+license = { workspace = true }
+edition = { workspace = true }
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+all-features = true
+rustdoc-args = ["--cfg=docsrs"]
+
+[dependencies]
+borsh = { workspace = true, optional = true }
+bs58 = { workspace = true }
+solana-atomic-u64 = { workspace = true }
+solana-frozen-abi = { workspace = true, optional = true, features = [
+    "frozen-abi",
+] }
+solana-frozen-abi-macro = { workspace = true, optional = true, features = [
+    "frozen-abi",
+] }
+solana-hash = { workspace = true }
+solana-sanitize = { workspace = true }
+serde = { workspace = true, optional = true }
+serde_derive = { workspace = true, optional = true }
+
+[target.'cfg(not(target_os = "solana"))'.dependencies]
+sha3 = { workspace = true }
+
+[target.'cfg(target_os = "solana")'.dependencies]
+# sha3 should be removed in the next breaking release,
+# as there's no reason to use the crate instead of the syscall
+# onchain
+sha3 = { workspace = true, optional = true }
+solana-define-syscall = { workspace = true }
+
+[features]
+borsh = ["dep:borsh"]
+frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
+serde = ["dep:serde", "dep:serde_derive"]
+sha3 = ["dep:sha3"]
+
+[lints]
+workspace = true
diff --git a/sdk/program/src/keccak.rs b/sdk/keccak-hasher/src/lib.rs
similarity index 61%
rename from sdk/program/src/keccak.rs
rename to sdk/keccak-hasher/src/lib.rs
index cf94dfa4287722..d023523c84a271 100644
--- a/sdk/program/src/keccak.rs
+++ b/sdk/keccak-hasher/src/lib.rs
@@ -1,34 +1,45 @@
 //! Hashing with the [keccak] (SHA-3) hash function.
 //!
 //! [keccak]: https://keccak.team/keccak.html
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
 
 #[cfg(feature = "borsh")]
 use borsh::{BorshDeserialize, BorshSchema, BorshSerialize};
+#[cfg(any(feature = "sha3", not(target_os = "solana")))]
+use sha3::{Digest, Keccak256};
+pub use solana_hash::{ParseHashError, HASH_BYTES, MAX_BASE58_LEN};
 use {
-    sha3::{Digest, Keccak256},
     solana_sanitize::Sanitize,
-    std::{convert::TryFrom, fmt, str::FromStr},
-    thiserror::Error,
+    std::{fmt, str::FromStr},
 };
 
-pub const HASH_BYTES: usize = 32;
-/// Maximum string length of a base58 encoded hash
-const MAX_BASE58_LEN: usize = 44;
-#[cfg_attr(feature = "frozen-abi", derive(AbiExample))]
+// TODO: replace this with `solana_hash::Hash` in the
+// next breaking change.
+// It's a breaking change because the field is public
+// here and private in `solana_hash`, and making
+// it public in `solana_hash` would break wasm-bindgen
+#[cfg_attr(feature = "frozen-abi", derive(solana_frozen_abi_macro::AbiExample))]
 #[cfg_attr(
     feature = "borsh",
     derive(BorshSerialize, BorshDeserialize, BorshSchema),
     borsh(crate = "borsh")
 )]
-#[derive(Serialize, Deserialize, Clone, Copy, Default, Eq, PartialEq, Ord, PartialOrd, Hash)]
+#[cfg_attr(
+    feature = "serde",
+    derive(serde_derive::Deserialize, serde_derive::Serialize)
+)]
+#[derive(Clone, Copy, Default, Eq, PartialEq, Ord, PartialOrd, Hash)]
 #[repr(transparent)]
 pub struct Hash(pub [u8; HASH_BYTES]);
 
+#[cfg(any(feature = "sha3", not(target_os = "solana")))]
 #[derive(Clone, Default)]
 pub struct Hasher {
     hasher: Keccak256,
 }
 
+#[cfg(any(feature = "sha3", not(target_os = "solana")))]
 impl Hasher {
     pub fn hash(&mut self, val: &[u8]) {
         self.hasher.update(val);
@@ -43,6 +54,18 @@ impl Hasher {
     }
 }
 
+impl From<solana_hash::Hash> for Hash {
+    fn from(val: solana_hash::Hash) -> Self {
+        Self(val.to_bytes())
+    }
+}
+
+impl Into<solana_hash::Hash> for Hash {
+    fn into(self) -> solana_hash::Hash {
+        solana_hash::Hash::new_from_array(self.0)
+    }
+}
+
 impl Sanitize for Hash {}
 
 impl AsRef<[u8]> for Hash {
@@ -53,46 +76,32 @@ impl AsRef<[u8]> for Hash {
 
 impl fmt::Debug for Hash {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", bs58::encode(self.0).into_string())
+        let converted: solana_hash::Hash = (*self).into();
+        fmt::Debug::fmt(&converted, f)
     }
 }
 
 impl fmt::Display for Hash {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", bs58::encode(self.0).into_string())
+        let converted: solana_hash::Hash = (*self).into();
+        fmt::Display::fmt(&converted, f)
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Error)]
-pub enum ParseHashError {
-    #[error("string decoded to wrong size for hash")]
-    WrongSize,
-    #[error("failed to decoded string to hash")]
-    Invalid,
-}
-
 impl FromStr for Hash {
     type Err = ParseHashError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        if s.len() > MAX_BASE58_LEN {
-            return Err(ParseHashError::WrongSize);
-        }
-        bs58::decode(s)
-            .into_vec()
-            .map_err(|_| ParseHashError::Invalid)
-            .and_then(|bytes| {
-                <[u8; HASH_BYTES]>::try_from(bytes)
-                    .map(Hash::new_from_array)
-                    .map_err(|_| ParseHashError::WrongSize)
-            })
+        let unconverted = solana_hash::Hash::from_str(s)?;
+        Ok(unconverted.into())
     }
 }
 
 impl Hash {
     #[deprecated(since = "2.2.0", note = "Use 'Hash::new_from_array' instead")]
     pub fn new(hash_slice: &[u8]) -> Self {
-        Hash(<[u8; HASH_BYTES]>::try_from(hash_slice).unwrap())
+        #[allow(deprecated)]
+        Self::from(solana_hash::Hash::new(hash_slice))
     }
 
     pub const fn new_from_array(hash_array: [u8; HASH_BYTES]) -> Self {
@@ -101,13 +110,7 @@ impl Hash {
 
     /// unique Hash for tests and benchmarks.
     pub fn new_unique() -> Self {
-        use solana_atomic_u64::AtomicU64;
-        static I: AtomicU64 = AtomicU64::new(1);
-
-        let mut b = [0u8; HASH_BYTES];
-        let i = I.fetch_add(1);
-        b[0..8].copy_from_slice(&i.to_le_bytes());
-        Self::new_from_array(b)
+        Self::from(solana_hash::Hash::new_unique())
     }
 
     pub fn to_bytes(self) -> [u8; HASH_BYTES] {
@@ -130,7 +133,7 @@ pub fn hashv(vals: &[&[u8]]) -> Hash {
     {
         let mut hash_result = [0; HASH_BYTES];
         unsafe {
-            crate::syscalls::sol_keccak256(
+            solana_define_syscall::definitions::sol_keccak256(
                 vals as *const _ as *const u8,
                 vals.len() as u64,
                 &mut hash_result as *mut _ as *mut u8,
diff --git a/sdk/program/Cargo.toml b/sdk/program/Cargo.toml
index 141773c4f789df..4eba8b6d88d82e 100644
--- a/sdk/program/Cargo.toml
+++ b/sdk/program/Cargo.toml
@@ -54,6 +54,7 @@ solana-instruction = { workspace = true, default-features = false, features = [
     "serde",
     "std",
 ] }
+solana-keccak-hasher = { workspace = true }
 solana-last-restart-slot = { workspace = true, features = ["serde", "sysvar"] }
 solana-msg = { workspace = true }
 solana-native-token = { workspace = true }
diff --git a/sdk/program/src/lib.rs b/sdk/program/src/lib.rs
index 55da6831369d8f..4cb41e6cbed3cd 100644
--- a/sdk/program/src/lib.rs
+++ b/sdk/program/src/lib.rs
@@ -484,7 +484,6 @@ pub mod feature;
 pub mod hash;
 pub mod incinerator;
 pub mod instruction;
-pub mod keccak;
 pub mod lamports;
 pub mod loader_instruction;
 pub mod loader_upgradeable_instruction;
@@ -522,6 +521,8 @@ pub use solana_borsh::v1 as borsh1;
 pub use solana_epoch_rewards as epoch_rewards;
 #[deprecated(since = "2.1.0", note = "Use `solana-fee-calculator` crate instead")]
 pub use solana_fee_calculator as fee_calculator;
+#[deprecated(since = "2.2.0", note = "Use `solana-keccak-hasher` crate instead")]
+pub use solana_keccak_hasher as keccak;
 #[deprecated(since = "2.1.0", note = "Use `solana-last-restart-slot` crate instead")]
 pub use solana_last_restart_slot as last_restart_slot;
 #[deprecated(since = "2.1.0", note = "Use `solana-program-memory` crate instead")]

From 8ad2b988ba774adef48897f704ff7723893af706 Mon Sep 17 00:00:00 2001
From: kevinheavey <heaveykevin2@gmail.com>
Date: Thu, 31 Oct 2024 15:07:39 +0400
Subject: [PATCH 2/7] fix lint

---
 sdk/keccak-hasher/src/lib.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sdk/keccak-hasher/src/lib.rs b/sdk/keccak-hasher/src/lib.rs
index d023523c84a271..5c2ec004ead454 100644
--- a/sdk/keccak-hasher/src/lib.rs
+++ b/sdk/keccak-hasher/src/lib.rs
@@ -60,9 +60,9 @@ impl From<solana_hash::Hash> for Hash {
     }
 }
 
-impl Into<solana_hash::Hash> for Hash {
-    fn into(self) -> solana_hash::Hash {
-        solana_hash::Hash::new_from_array(self.0)
+impl From<Hash> for solana_hash::Hash {
+    fn from(val: Hash) -> Self {
+        Self::new_from_array(val.0)
     }
 }
 

From 8f8758459a76eb59d3a2026aa77a164c56e5a50f Mon Sep 17 00:00:00 2001
From: kevinheavey <heaveykevin2@gmail.com>
Date: Thu, 31 Oct 2024 15:36:52 +0400
Subject: [PATCH 3/7] sort deps

---
 sdk/keccak-hasher/Cargo.toml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sdk/keccak-hasher/Cargo.toml b/sdk/keccak-hasher/Cargo.toml
index 18fa2c11151acc..19f80c4f117550 100644
--- a/sdk/keccak-hasher/Cargo.toml
+++ b/sdk/keccak-hasher/Cargo.toml
@@ -17,6 +17,8 @@ rustdoc-args = ["--cfg=docsrs"]
 [dependencies]
 borsh = { workspace = true, optional = true }
 bs58 = { workspace = true }
+serde = { workspace = true, optional = true }
+serde_derive = { workspace = true, optional = true }
 solana-atomic-u64 = { workspace = true }
 solana-frozen-abi = { workspace = true, optional = true, features = [
     "frozen-abi",
@@ -26,8 +28,6 @@ solana-frozen-abi-macro = { workspace = true, optional = true, features = [
 ] }
 solana-hash = { workspace = true }
 solana-sanitize = { workspace = true }
-serde = { workspace = true, optional = true }
-serde_derive = { workspace = true, optional = true }
 
 [target.'cfg(not(target_os = "solana"))'.dependencies]
 sha3 = { workspace = true }

From 00499e9205db7d5f8b8ed10a04afeb31c55e930f Mon Sep 17 00:00:00 2001
From: kevinheavey <heaveykevin2@gmail.com>
Date: Thu, 31 Oct 2024 17:27:23 +0400
Subject: [PATCH 4/7] missing feature

---
 sdk/program/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sdk/program/Cargo.toml b/sdk/program/Cargo.toml
index 4eba8b6d88d82e..1db2814a97d495 100644
--- a/sdk/program/Cargo.toml
+++ b/sdk/program/Cargo.toml
@@ -54,7 +54,7 @@ solana-instruction = { workspace = true, default-features = false, features = [
     "serde",
     "std",
 ] }
-solana-keccak-hasher = { workspace = true }
+solana-keccak-hasher = { workspace = true, features = ["sha3"] }
 solana-last-restart-slot = { workspace = true, features = ["serde", "sysvar"] }
 solana-msg = { workspace = true }
 solana-native-token = { workspace = true }

From 0688483372d12c3106d6ce374c853e103c18cb5e Mon Sep 17 00:00:00 2001
From: kevinheavey <heaveykevin2@gmail.com>
Date: Mon, 18 Nov 2024 17:53:36 +0400
Subject: [PATCH 5/7] update lock file

---
 svm/examples/Cargo.lock | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/svm/examples/Cargo.lock b/svm/examples/Cargo.lock
index 8e5b6843bd91c7..3a5a15e3354a5f 100644
--- a/svm/examples/Cargo.lock
+++ b/svm/examples/Cargo.lock
@@ -5570,6 +5570,18 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "solana-keccak-hasher"
+version = "2.2.0"
+dependencies = [
+ "bs58",
+ "sha3",
+ "solana-atomic-u64",
+ "solana-define-syscall",
+ "solana-hash",
+ "solana-sanitize",
+]
+
 [[package]]
 name = "solana-keypair"
 version = "2.2.0"
@@ -5916,6 +5928,7 @@ dependencies = [
  "solana-fee-calculator",
  "solana-hash",
  "solana-instruction",
+ "solana-keccak-hasher",
  "solana-last-restart-slot",
  "solana-msg",
  "solana-native-token",

From aa4077af004f819b52374adcee4a8e647a332b93 Mon Sep 17 00:00:00 2001
From: kevinheavey <heaveykevin2@gmail.com>
Date: Wed, 20 Nov 2024 04:42:57 +0400
Subject: [PATCH 6/7] remove unused deps

---
 Cargo.lock                   | 2 --
 programs/sbf/Cargo.lock      | 2 --
 sdk/keccak-hasher/Cargo.toml | 2 --
 svm/examples/Cargo.lock      | 2 --
 4 files changed, 8 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index cd2e2777a412b0..8fb169c4940812 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -7201,11 +7201,9 @@ name = "solana-keccak-hasher"
 version = "2.2.0"
 dependencies = [
  "borsh 1.5.3",
- "bs58",
  "serde",
  "serde_derive",
  "sha3",
- "solana-atomic-u64",
  "solana-define-syscall",
  "solana-frozen-abi",
  "solana-frozen-abi-macro",
diff --git a/programs/sbf/Cargo.lock b/programs/sbf/Cargo.lock
index 8d29cb8c9e1af3..69e4fb808ecba6 100644
--- a/programs/sbf/Cargo.lock
+++ b/programs/sbf/Cargo.lock
@@ -5753,9 +5753,7 @@ dependencies = [
 name = "solana-keccak-hasher"
 version = "2.2.0"
 dependencies = [
- "bs58",
  "sha3",
- "solana-atomic-u64",
  "solana-define-syscall",
  "solana-hash",
  "solana-sanitize",
diff --git a/sdk/keccak-hasher/Cargo.toml b/sdk/keccak-hasher/Cargo.toml
index 19f80c4f117550..4d77dba2eb8270 100644
--- a/sdk/keccak-hasher/Cargo.toml
+++ b/sdk/keccak-hasher/Cargo.toml
@@ -16,10 +16,8 @@ rustdoc-args = ["--cfg=docsrs"]
 
 [dependencies]
 borsh = { workspace = true, optional = true }
-bs58 = { workspace = true }
 serde = { workspace = true, optional = true }
 serde_derive = { workspace = true, optional = true }
-solana-atomic-u64 = { workspace = true }
 solana-frozen-abi = { workspace = true, optional = true, features = [
     "frozen-abi",
 ] }
diff --git a/svm/examples/Cargo.lock b/svm/examples/Cargo.lock
index 3a5a15e3354a5f..851010dd0db9f6 100644
--- a/svm/examples/Cargo.lock
+++ b/svm/examples/Cargo.lock
@@ -5574,9 +5574,7 @@ dependencies = [
 name = "solana-keccak-hasher"
 version = "2.2.0"
 dependencies = [
- "bs58",
  "sha3",
- "solana-atomic-u64",
  "solana-define-syscall",
  "solana-hash",
  "solana-sanitize",

From 5d5a49c7ecbbeab53c7036a53c8a8915113aa5cb Mon Sep 17 00:00:00 2001
From: kevinheavey <heaveykevin2@gmail.com>
Date: Wed, 20 Nov 2024 11:49:16 +0400
Subject: [PATCH 7/7] make std optional

---
 sdk/keccak-hasher/Cargo.toml |  5 +++--
 sdk/keccak-hasher/src/lib.rs | 13 ++++++++++---
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/sdk/keccak-hasher/Cargo.toml b/sdk/keccak-hasher/Cargo.toml
index 4d77dba2eb8270..91fd59b41973ea 100644
--- a/sdk/keccak-hasher/Cargo.toml
+++ b/sdk/keccak-hasher/Cargo.toml
@@ -38,10 +38,11 @@ sha3 = { workspace = true, optional = true }
 solana-define-syscall = { workspace = true }
 
 [features]
-borsh = ["dep:borsh"]
-frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro"]
+borsh = ["dep:borsh", "std"]
+frozen-abi = ["dep:solana-frozen-abi", "dep:solana-frozen-abi-macro", "std"]
 serde = ["dep:serde", "dep:serde_derive"]
 sha3 = ["dep:sha3"]
+std = ["solana-hash/std"]
 
 [lints]
 workspace = true
diff --git a/sdk/keccak-hasher/src/lib.rs b/sdk/keccak-hasher/src/lib.rs
index 5c2ec004ead454..b0a18694c50e5a 100644
--- a/sdk/keccak-hasher/src/lib.rs
+++ b/sdk/keccak-hasher/src/lib.rs
@@ -3,15 +3,21 @@
 //! [keccak]: https://keccak.team/keccak.html
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 #![cfg_attr(feature = "frozen-abi", feature(min_specialization))]
+#![no_std]
+#[cfg(feature = "std")]
+extern crate std;
 
-#[cfg(feature = "borsh")]
-use borsh::{BorshDeserialize, BorshSchema, BorshSerialize};
 #[cfg(any(feature = "sha3", not(target_os = "solana")))]
 use sha3::{Digest, Keccak256};
 pub use solana_hash::{ParseHashError, HASH_BYTES, MAX_BASE58_LEN};
+#[cfg(feature = "borsh")]
+use {
+    borsh::{BorshDeserialize, BorshSchema, BorshSerialize},
+    std::string::ToString,
+};
 use {
+    core::{fmt, str::FromStr},
     solana_sanitize::Sanitize,
-    std::{fmt, str::FromStr},
 };
 
 // TODO: replace this with `solana_hash::Hash` in the
@@ -148,6 +154,7 @@ pub fn hash(val: &[u8]) -> Hash {
     hashv(&[val])
 }
 
+#[cfg(feature = "std")]
 /// Return the hash of the given hash extended with the given value.
 pub fn extend_and_hash(id: &Hash, val: &[u8]) -> Hash {
     let mut hash_data = id.as_ref().to_vec();