struct Node<T: ?Sized + Send> {
    next: Option<Box<Node<Send>>>,
    value: T,
}
fn clear(head: &mut Option<Box<Node<Send>>>) {
    while let Some(node) = head.take() {
        *head = node.next;
    }
}
fn main() {}

rustc: /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/llvm/lib/IR/Instructions.cpp:263: void llvm::CallInst::init(llvm::FunctionType*, llvm::Value*, llvm::ArrayRef<llvm::Value*>, llvm::ArrayRef<llvm::OperandBundleDefT<llvm::Value*> >, const llvm::Twine&): Assertion `(i >= FTy->getNumParams() || FTy->getParamType(i) == Args[i]->getType()) && "Calling a function with a bad signature!"' failed.