ABI

I just followed “The Rust Reference: 17. Application Binary Interface (ABI)” and “The Embedded Rust Book: 10.2 A little Rust with your C” After then, I tried to expose Rust program to C as ABI. Test the code in the first reference foo.rs: // This is kept because of `#[used]`: #[used] static FOO: u32 = 123; // This is removable because it is unused: #[allow(dead_code)] static BAR: u32 = 0; // This is kept because it is publicly reachable: pub static BAZ: u32 = 0; // This is kept because it is referenced by a public, reachable function: static QUUX: u32 = 0; pub fn quux() -> &'static u32 { &QUUX } // This is removable because it is referenced by a private, unused (dead) function: static CORGE: u32 = 0; #[allow(dead_code)] fn corge() -> &'static u32 { &CORGE } used attribute The attribute can only be applied to static item.

While learning “15.3. Running Code on Cleanup with the Drop Trait” of the Rust official book, I just wondered the memory layout of Rust program. TL;DR: Currently the default global allocator is unspecified. Libraries, however, like cdylibs and staticlibs are guaranteed to use the System by default. Struct std::alloc::System: The default memory allocator provided by the operating system. This is based on malloc on Unix platforms and HeapAlloc on Windows, plus related functions.