为什么本地变量没有足够长的时间用于thread :: scoped？

Question

为什么没有示例1编译，因为示例2编译得很好？示例之间的唯一区别在于示例1中value是函数局部变量，而示例2中value是函数的参数。

示例1

#![feature(scoped)]

use std::thread;
use std::sync::atomic::{AtomicUsize, Ordering};

pub fn foo<F>() {
    let mut join_guards = Vec::new();
    let value = AtomicUsize::new(0);

    for _ in 0..10 {
        join_guards.push(thread::scoped(|| {
            value.fetch_add(1, Ordering::SeqCst);
        }));
    }
}

示例2

#![feature(scoped)]

use std::thread;
use std::sync::atomic::{AtomicUsize, Ordering};

pub fn foo<F>(value: AtomicUsize) {
    let mut join_guards = Vec::new();

    for _ in 0..10 {
        join_guards.push(thread::scoped(|| {
            value.fetch_add(1, Ordering::SeqCst);
        }));
    }
}

这些是我尝试编译示例1的错误消息：

error: `value` does not live long enough
         join_guards.push(thread::scoped(|| {
             value.fetch_add(1, Ordering::SeqCst);
         }));
note: reference must be valid for the block at 6:20...
pub fn foo<F>() {
    let mut join_guards = Vec::new();
    let value = AtomicUsize::new(0);

     for _ in 0..10 {
         join_guards.push(thread::scoped(|| {

note: ...but borrowed value is only valid for the block suffix following statement 1 at 8:40
    let value = AtomicUsize::new(0);

     for _ in 0..10 {
         join_guards.push(thread::scoped(|| {
             value.fetch_add(1, Ordering::SeqCst);
         }));