A borrow of a thread-local variable was made inside a function which outlived the lifetime of the function.
Erroneous code example:
#![feature(thread_local)]
#[thread_local]
static FOO: u8 = 3;
fn main() {
let a = &FOO; // error: thread-local variable borrowed past end of function
std::thread::spawn(move || {
println!("{}", a);
});
}