Function no_stack_overflow_on_drop

regex/regex-syntax/src/hir/mod.rs:2155–2191

()

    #[test]
    #[cfg(any(unix, windows))]
    fn no_stack_overflow_on_drop() {
        use std::thread;

        let run = || {
            let mut expr = Hir::empty();
            for _ in 0..100 {
                expr = Hir::group(Group {
                    kind: GroupKind::NonCapturing,
                    hir: Box::new(expr),
                });
                expr = Hir::repetition(Repetition {
                    kind: RepetitionKind::ZeroOrOne,
                    greedy: true,
                    hir: Box::new(expr),
                });

                expr = Hir {
                    kind: HirKind::Concat(vec![expr]),
                    info: HirInfo::new(),
                };
                expr = Hir {
                    kind: HirKind::Alternation(vec![expr]),
                    info: HirInfo::new(),
                };
            }
            assert!(!expr.kind.is_empty());
        };

        // We run our test on a thread with a small stack size so we can
        // force the issue more easily.
        thread::Builder::new()
            .stack_size(1<<10)
            .spawn(run)
            .unwrap()
            .join()
            .unwrap();
    }
}