Move fn to sdk

programs/stake/src/stake_state.rs

@@ -14,7 +14,7 @@ use solana_sdk::{
     account_utils::{State, StateMut},
     clock::{Clock, Epoch, UnixTimestamp},
     ic_msg,
-    instruction::InstructionError,
+    instruction::{checked_add, InstructionError},
     keyed_account::KeyedAccount,
     process_instruction::InvokeContext,
     pubkey::Pubkey,
@@ -70,13 +70,6 @@ impl Default for StakeState {
     }
 }
 
-fn checked_add(a: u64, b: u64) -> Result<u64, InstructionError> {
-    match a.checked_add(b) {
-        Some(sum) => Ok(sum),
-        None => Err(InstructionError::InsufficientFunds),
-    }
-}
-
 impl StakeState {
     pub fn get_rent_exempt_reserve(rent: &Rent) -> u64 {
         rent.minimum_balance(std::mem::size_of::<StakeState>())

sdk/program/src/instruction.rs

@@ -209,6 +209,13 @@ impl Instruction {
     }
 }
 
+pub fn checked_add(a: u64, b: u64) -> Result<u64, InstructionError> {
+    match a.checked_add(b) {
+        Some(sum) => Ok(sum),
+        None => Err(InstructionError::InsufficientFunds),
+    }
+}
+
 /// Account metadata used to define Instructions
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
 pub struct AccountMeta {