rust

---

description: "Rust best practices for Solana smart contract development using Anchor framework and Solana SDK" globs: programs//*.rs, src//.rs, tests/**/.ts alwaysApply: false

Rust + Solana (Anchor) Best Practices

Program Structure

• Structure Solana programs using Anchor framework standards
• Place program entrypoint logic in lib.rs, not main.rs
• Organize handlers into modules (e.g., initialize, update, close)
• Separate state definitions, errors, instructions, and utils
• Group reusable logic under a utils module (e.g., account validation)
• Use declare_id!() to define program ID

Anchor Framework

• Use #[derive(Accounts)] for all instruction contexts
• Validate accounts strictly using constraint macros (e.g., #[account(mut)], seeds, bump])
• Define all state structs with #[account] and #[derive(AnchorSerialize, AnchorDeserialize)]
• Prefer Init, Close, Realloc, Mut, and constraint macros to avoid manual deserialization
• Use ctx.accounts to access validated context accounts
• Handle CPI (Cross-Program Invocation) calls via Anchor’s CPI helpers

Serialization

• Use Borsh or Anchor's custom serializer (not Serde) for on-chain data
• Always include #[account(zero_copy)] or #[repr(C)] for packed structures
• Avoid floating point types — use u64, u128, or fixed-point math
• Zero out or close unused accounts to reduce rent costs

Testing

• Write tests in TypeScript using Anchor’s Mocha + Chai setup (tests/*.ts)
• Use anchor.workspace.MyProgram to load deployed contracts
• Use provider.simulate() to inspect failed txs
• Spin up a local validator (anchor test) and reset between tests
• Airdrop SOL to wallets with provider.connection.requestAirdrop(...)
• Validate program logs using tx.confirmation.logMessages

Solana SDK (Manual)

• Use solana_program crate when not using Anchor (bare-metal programs)
• Carefully deserialize accounts using AccountInfo, try_from_slice_unchecked
• Use solana_program::msg! for lightweight debugging logs
• Verify accounts via is_signer, is_writable, key == expected
• Never panic! Use ProgramError::Custom(u32) or ErrorCode enums