Macro custom_heap 

macro_rules! custom_heap {
    () => { ... };
}

On Solana, defines BumpAllocator as the global allocator.

When compiling for Solana, defines a new instance of BumpAllocator and declares it as a the global allocator. When compiling for other platforms, does nothing.

Note that, as always when defining custom global allocator on Solana, if using solana_program::entrypoint or anchor::program macros, the smart contract must define and enable custom-heap feature. Otherwise, global allocator defined by this macro and in solana_program will clash.

Example

#[cfg(not(feature = "cpi"))]
solana_allocator::custom_heap!();