Feature Flags

Solana

#[cfg(feature = "devnet")]
pub const RANDOM_CONSTANT: u64 = 1;
#[cfg(not(feature = "devnet"))]
pub const RANDOM_CONSTANT: u64 = 2;

#[cfg(feature = "devnet")]
msg!("This should only be logged when devnet is enabled!")

Then run

anchor build — --features devnet