stack_box 1.0.0

store unsize struct on stack
Documentation 
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# stack_box


Put your tiny stuff on stack!

If you are sure your stuff has or uses less than an exact size, but the compiler doesn't see
and force you to put them on heap, this crate is for you.

```rust
use std::fmt::Debug;

use stack_box::{stackbox_coerce, FitStackBox};

// alias to a `StackBox` that could exactly contains a `[u32; 3]`
type U32Box<T> = FitStackBox!(T, [u32; 3]);

fn main() {
    let u8_box = U32Box::new(16u16).unwrap(); // ok
    let u32_box = U32Box::new([32u32; 3]).unwrap(); // ok

    assert!(U32Box::new([0u32; 4]).is_none()); // size too large
    assert!(U32Box::new(0u64).is_none()); // align too large

    let arr: [U32Box<dyn Debug>; 2] = [coerce!(u8_box), coerce!(u32_box)];

    for x in arr {
        dbg!(&*x);
    }
}
```

The expansion of `coerce` macro is also safe rust code.