Undefined uninitialized behaviour panic on nightly since 1.49.0

[norru]

I got 100% panic since upgrading nightly to 1.49.0. This causes 100% crash when writing images.

Update: reproduced in rust 1.51.0-nightly

This needs looking into as it kind of makes the library completely unusable on newer versions of rustc

rustc 1.49.0-nightly (31530e5d1 2020-10-20)

rust-lang/rust#73573

nico@devuan-3xS:~/Projects/3rdParty/openexr-rs$ RUST_BACKTRACE=1 cargo test
warning: use of deprecated function `std::mem::uninitialized`: use `mem::MaybeUninit` instead
   --> src/frame_buffer.rs:215:36
    |
215 |         let mut channel = unsafe { mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(deprecated)]` on by default

warning: use of deprecated function `std::mem::uninitialized`: use `mem::MaybeUninit` instead
   --> src/header.rs:356:33
    |
356 |         let mut name = unsafe { std::mem::uninitialized() };
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^

warning: use of deprecated function `std::mem::uninitialized`: use `mem::MaybeUninit` instead
   --> src/header.rs:357:36
    |
357 |         let mut channel = unsafe { std::mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^

warning: the type `CEXR_Channel` does not permit being left uninitialized
   --> src/frame_buffer.rs:215:36
    |
215 |         let mut channel = unsafe { mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^^^
    |                                    |
    |                                    this code causes undefined behavior when executed
    |                                    help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
    |
    = note: `#[warn(invalid_value)]` on by default
note: enums have to be initialized to a variant
   --> /home/nico/Projects/3rdParty/openexr-rs/openexr-sys/src/bindings.rs:105:1
    |
105 | pub enum CEXR_PixelType { UINT = 0, HALF = 1, FLOAT = 2, }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: the type `CEXR_Channel` does not permit being left uninitialized
   --> src/header.rs:357:36
    |
357 |         let mut channel = unsafe { std::mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^
    |                                    |
    |                                    this code causes undefined behavior when executed
    |                                    help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
    |
note: enums have to be initialized to a variant
   --> /home/nico/Projects/3rdParty/openexr-rs/openexr-sys/src/bindings.rs:105:1
    |
105 | pub enum CEXR_PixelType { UINT = 0, HALF = 1, FLOAT = 2, }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: 5 warnings emitted

warning: use of deprecated function `std::mem::uninitialized`: use `mem::MaybeUninit` instead
   --> src/frame_buffer.rs:215:36
    |
215 |         let mut channel = unsafe { mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(deprecated)]` on by default

warning: use of deprecated function `std::mem::uninitialized`: use `mem::MaybeUninit` instead
   --> src/header.rs:356:33
    |
356 |         let mut name = unsafe { std::mem::uninitialized() };
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^

warning: use of deprecated function `std::mem::uninitialized`: use `mem::MaybeUninit` instead
   --> src/header.rs:357:36
    |
357 |         let mut channel = unsafe { std::mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^

warning: the type `CEXR_Channel` does not permit being left uninitialized
   --> src/frame_buffer.rs:215:36
    |
215 |         let mut channel = unsafe { mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^^^
    |                                    |
    |                                    this code causes undefined behavior when executed
    |                                    help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
    |
    = note: `#[warn(invalid_value)]` on by default
note: enums have to be initialized to a variant
   --> /home/nico/Projects/3rdParty/openexr-rs/openexr-sys/src/bindings.rs:105:1
    |
105 | pub enum CEXR_PixelType { UINT = 0, HALF = 1, FLOAT = 2, }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: the type `CEXR_Channel` does not permit being left uninitialized
   --> src/header.rs:357:36
    |
357 |         let mut channel = unsafe { std::mem::uninitialized() };
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^
    |                                    |
    |                                    this code causes undefined behavior when executed
    |                                    help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
    |
note: enums have to be initialized to a variant
   --> /home/nico/Projects/3rdParty/openexr-rs/openexr-sys/src/bindings.rs:105:1
    |
105 | pub enum CEXR_PixelType { UINT = 0, HALF = 1, FLOAT = 2, }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: 5 warnings emitted

    Finished test [unoptimized + debuginfo] target(s) in 0.01s
     Running target/debug/deps/openexr-820bdf9eb2e33d8f

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running target/debug/deps/incremental_io-df68b4539a48d82c

running 1 test
test incremental_io ... FAILED

failures:

---- incremental_io stdout ----
thread 'incremental_io' panicked at 'attempted to leave type `openexr_sys::CEXR_Channel` uninitialized, which is invalid', /home/nico/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/mem/mod.rs:659:9
stack backtrace:
   0: rust_begin_unwind
             at /rustc/158f8d034b15e65ba8dc0d066358dd0632bfcd6e/library/std/src/panicking.rs:493:5
   1: core::panicking::panic_fmt
             at /rustc/158f8d034b15e65ba8dc0d066358dd0632bfcd6e/library/core/src/panicking.rs:92:14
   2: core::panicking::panic
             at /rustc/158f8d034b15e65ba8dc0d066358dd0632bfcd6e/library/core/src/panicking.rs:50:5
   3: core::mem::uninitialized
             at /home/nico/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/mem/mod.rs:659:9
   4: <openexr::header::ChannelIter as core::iter::traits::iterator::Iterator>::next
             at ./src/header.rs:357:36
   5: openexr::header::Header::validate_framebuffer_for_output
             at ./src/header.rs:262:21
   6: openexr::output::scanline_output_file::ScanlineOutputFile::write_pixels_incremental
             at ./src/output/scanline_output_file.rs:244:9
   7: incremental_io::incremental_io
             at ./tests/incremental_io.rs:27:9
   8: incremental_io::incremental_io::{{closure}}
             at ./tests/incremental_io.rs:8:1
   9: core::ops::function::FnOnce::call_once
             at /home/nico/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5
  10: core::ops::function::FnOnce::call_once
             at /rustc/158f8d034b15e65ba8dc0d066358dd0632bfcd6e/library/core/src/ops/function.rs:227:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.


failures:
    incremental_io

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.01s

error: test failed, to rerun pass '--test incremental_io'

stable rustc 1.47.0 does not trigger the panic.

[cessen]

Ah! Thank you for finding and reporting this. I'll take a look the next chance I get (though I'm a bit busy at the moment).

If you need a fix urgently, feel free to make a fix yourself and submit a PR, and I'll do my best to review, merge, and make a release with that more quickly.

[norru]

Hi, unfortunately I am unable to work on this right now, thanks for acknowledging the issue in the meantime though. Thanks, Nico

…

On Wed, 21 Oct 2020, 22:43 Nathan Vegdahl, ***@***.***> wrote: Ah! Thank you for finding and reporting this. I'll take a look the next chance I get (though I'm a bit busy at the moment). If you need a fix urgently, feel free to make a fix yourself and submit a PR, and I'll do my best to review, merge, and make a release with that more quickly. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#42 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAGZDS3G7LVJ5474OHWJKOLSL5IXXANCNFSM4SZT35WQ> .

[norru]

Attempted fix in #45