rust/cpp_kernel/cpp.rs

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// Rust Protobuf runtime using the C++ kernel.

use std::boxed::Box;

/// TODO(b/272728844): Replace this placeholder code with a real implementation.
#[repr(C)]
pub struct Arena {
    _data: [u8; 0],
}

impl Arena {
    pub unsafe fn new() -> *mut Self {
        let arena = Box::new(Arena { _data: [] });
        Box::leak(arena) as *mut _
    }

    pub unsafe fn free(arena: *mut Self) {
        let arena = Box::from_raw(arena);
        std::mem::drop(arena);
    }
}