macro_rules! hopper_exact_entrypoint {
( $( ( $disc:literal $( if $guard:expr )?, $bound:expr, $helper:path ) ),* $(,)? ) => { ... };
}Expand description
Declare the count-exact program entrypoint.
Reads the discriminator from the SIMD-0321 r2 instruction-data pointer
first, then materializes exactly the matched instruction’s declared
account bound before dispatching to the helper #[program] generated
for it. arms pairs each one-byte discriminator (optionally with an
if <const> guard, which folds the arm away when false) with that bound
and that helper. Each helper returns the entry’s own return code,
SUCCESS or the mapped error, so the dispatch is the entrypoint’s last
call. Accounts past the bound are neither materialized nor walked, and
there is no transaction-sized pointer table: the entry cost is the
declared accounts only. The Context (segment borrow registry, write
gate, parametric args) is built exactly as on the scanning path.
The r2 gate (5xXZc66h4UdB6Yq7FzdBxBiRAFMMScMLwHxk2QZDaNZL) is active
on mainnet-beta, devnet, and testnet. A runtime that leaves r2 zero
gets ProgramError::InvalidArgument back instead of a scanning
fallback, which keeps the dual-path code out of the binary; hopper feature-gate reports the gate for a target cluster.
A transaction that passes more accounts than the matched arm’s bound is
refused with ERR_TOO_MANY_ACCOUNTS before any account is walked:
the extra accounts would never be materialized, and a handler with
#[remaining_accounts(max = N)] must not run on a truncated list.