placing large array inside Box causes stack overflow

[XAMPPRocky]

I was trying to store a large array on the heap, the code produced a run-time error of stack overflow.

fn main() {
    let x = Box::new([0; 10_000_000]);
}

I expected the array to be initialised on the heap.

Instead it seems, the array is being initialised onto the stack, and then placed onto the heap, causing the this error message. thread '<main>' has overflowed its stack.

Meta

rustc --version --verbose:

rustc 1.2.0 (082e47636 2015-08-03)
binary: rustc
commit-hash: 082e4763615bdbe7b4dd3dfd6fc2210b7773edf5
commit-date: 2015-08-03
host: x86_64-apple-darwin
release: 1.2.0

[nagisa]

This is a known issue with Box::new (as well as Rc::new et al). It will be resolved once box syntax (and placement-in for the general case) get stabilised. For now do

#[feature(box_syntax)]
fn main() {
    let x = box [0; 10_000_000];
}

on nightlies instead.

[steveklabnik]

@nagisa is correct. While sometimes LLVM will do the right thing here, it will only be guaranteed with box.

Thank you for filing!