iOS app panics on will_terminate

[extrawurst]

Bevy version

bevy 0.15

[Optional] Relevant system information

MacOs 15.1.1 (24B91)
XCode 16.1 (16B40)

AdapterInfo { name: "Apple iOS simulator GPU", vendor: 0, device: 0, device_type: DiscreteGpu, driver: "", driver_info: "", backend: Metal }

What you did

Run the bevy_mobile_example in the XCode simulator and hard quit the app like in the video:

What went wrong

The debugger will trip over a panic we cause:

thread '<unnamed>' panicked at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wgpu-core-23.0.1/src/device/resource.rs:185:14:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread '<unnamed>' panicked at core/src/panicking.rs:221:5:
panic in a function that cannot unwind
stack backtrace:
   0:        0x1181e9464 - std::backtrace_rs::backtrace::libunwind::trace::h2504f6a7a9083436
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:        0x1181e9464 - std::backtrace_rs::backtrace::trace_unsynchronized::h6d30c5a7e5c0e95b
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:        0x1181e9464 - std::sys::backtrace::_print_fmt::h4d241177db3ad3db
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/sys/backtrace.rs:66:9
   3:        0x1181e9464 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h7a0e784acb8aeff7
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/sys/backtrace.rs:39:26
   4:        0x118229a64 - core::fmt::rt::Argument::fmt::hdcf4364f643ba5f0
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/core/src/fmt/rt.rs:177:76
   5:        0x118229a64 - core::fmt::write::hc7ae0c33f591ced7
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/core/src/fmt/mod.rs:1186:21
   6:        0x1181de7b4 - std::io::Write::write_fmt::h73a91b3d4edc8b40
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/io/mod.rs:1839:15
   7:        0x1181e9318 - std::sys::backtrace::BacktraceLock::print::ha96d44dc3d9057c0
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/sys/backtrace.rs:42:9
   8:        0x1181eb680 - std::panicking::default_hook::{{closure}}::h6410df3ad7c0548b
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/panicking.rs:268:22
   9:        0x1181eb4c8 - std::panicking::default_hook::h04f2d093d7cf1671
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/panicking.rs:295:9
  10:        0x1181ebed0 - std::panicking::rust_panic_with_hook::h5564521c80b92207
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/panicking.rs:801:13
  11:        0x1181ebb58 - std::panicking::begin_panic_handler::{{closure}}::h24bfefb8a0ebe306
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/panicking.rs:667:13
  12:        0x1181e9928 - std::sys::backtrace::__rust_end_short_backtrace::hc1a47cedc59d63b1
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/sys/backtrace.rs:170:18
  13:        0x1181eb838 - rust_begin_unwind
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/std/src/panicking.rs:665:5
  14:        0x1183b7c8c - core::panicking::panic_nounwind_fmt::runtime::h43645cfdb777a72f
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/core/src/panicking.rs:112:18
  15:        0x1183b7c8c - core::panicking::panic_nounwind_fmt::hddc48505d5cccc9b
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/core/src/panicking.rs:122:5
  16:        0x1183b7d04 - core::panicking::panic_nounwind::h56860050a0c8ebdc
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/core/src/panicking.rs:221:5
  17:        0x1183b7e7c - core::panicking::panic_cannot_unwind::h2956a5941768ddb3
                               at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf/library/core/src/panicking.rs:310:5
  18:        0x1136bdb08 - winit::platform_impl::ios::app_delegate::AppDelegate::will_terminate::h661a91142ff42459
                               at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/objc2-0.5.2/src/macros/declare_class.rs:981:25
  19:        0x185aabf20 - -[UIApplication _terminateWithStatus:]
  20:        0x1850be5c0 - -[_UISceneLifecycleMultiplexer _evalTransitionToSettings:fromSettings:forceExit:withTransitionStore:]
  21:        0x1850be2b0 - -[_UISceneLifecycleMultiplexer forceExitWithTransitionContext:scene:]
  22:        0x185aa40b4 - -[UIApplication workspaceShouldExit:withTransitionContext:]
  23:        0x1879c1a20 - ___63-[FBSWorkspaceScenesClient willTerminateWithTransitionContext:]_block_invoke_2
  24:        0x1879a1618 - -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:]
  25:        0x1879c19c4 - ___63-[FBSWorkspaceScenesClient willTerminateWithTransitionContext:]_block_invoke
  26:        0x102c267b8 - __dispatch_client_callout
  27:        0x102c2a3bc - __dispatch_block_invoke_direct
  28:        0x1879e4b58 - ___FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__
  29:        0x1879e4a34 - -[FBSMainRunLoopSerialQueue _targetQueue_performNextIfPossible]
  30:        0x1879e4b8c - -[FBSMainRunLoopSerialQueue _performNextFromRunLoopSource]
  31:        0x18041b324 - ___CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__
  32:        0x18041b26c - ___CFRunLoopDoSource0
  33:        0x18041a9d0 - ___CFRunLoopDoSources0
  34:        0x1804150b0 - ___CFRunLoopRun
  35:        0x180414960 - _CFRunLoopRunSpecific
  36:        0x190183b10 - _GSEventRunModal
  37:        0x185aa2b40 - -[UIApplication _run]
  38:        0x185aa6d38 - _UIApplicationMain
  39:        0x1135cc988 - winit::platform_impl::ios::event_loop::EventLoop<T>::run::hfa7364d038636774
                               at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/winit-0.30.5/src/platform_impl/ios/event_loop.rs:205:13
  40:        0x11358a788 - winit::event_loop::EventLoop<T>::run_app::he42ba14a079ab1c7
                               at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/winit-0.30.5/src/event_loop.rs:265:9
  41:        0x1135dcfe0 - bevy_winit::state::winit_runner::h5d5e3cc23a8cce33
                               at /Users/stephan/code/bevy/crates/bevy_winit/src/state.rs:862:23
  42:        0x1135c05bc - core::ops::function::FnOnce::call_once::hb835a59dade9cf38
                               at /Users/stephan/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  43:        0x1135c0384 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h5633b0124507a73d
                               at /Users/stephan/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  44:        0x117cff790 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h03e06b6b1483f27a
                               at /Users/stephan/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/boxed.rs:2454:9
  45:        0x117d26e80 - bevy_app::app::App::run::h639b4f1c8d6ff08d
                               at /Users/stephan/code/bevy/crates/bevy_app/src/app.rs:170:9
  46:        0x11355a62c - bevy_mobile_example::main::hacdf6324ea22c01b
                               at /Users/stephan/code/bevy/examples/mobile/src/lib.rs:16:5
  47:        0x11355a244 - main_rs
                               at /Users/stephan/code/bevy/examples/mobile/src/lib.rs:13:1
  48:        0x113557898 - main
                               at /Users/stephan/code/bevy/examples/mobile/ios-src/main.m:4:5

[alice-i-cecile]

39: 0x1135cc988 - winit::platform_impl::ios::event_loop::EventLoop::run::hfa7364d038636774
at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/winit-0.30.5/src/platform_impl/ios/event_loop.rs:205:13

This is the critical line. We're unwrapping somewhere in the windowing loop where we shouldn't be.

[jmskov]

@extrawurst Do you see this error message every time you hard quit the app? I can only reproduce this when I hard quit before the window loop begins. MacOS 15.3, XCode 16.2 w/ 18.0 target, Bevy 0.15.1 and 0.16-dev.

[extrawurst]

so this still fails everytime on 0.15.2 for me with this:

thread '<unnamed>' panicked at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wgpu-core-23.0.1/src/device/resource.rs:185:14:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread '<unnamed>' panicked at core/src/panicking.rs:223:5:
panic in a function that cannot unwind
stack backtrace:
   0:        0x1180a68ec - std::backtrace_rs::backtrace::libunwind::trace::hca517c2a2f3232d7
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:        0x1180a68ec - std::backtrace_rs::backtrace::trace_unsynchronized::hd7d769e02b4ac1b7
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:        0x1180a68ec - std::sys::backtrace::_print_fmt::h551e35a2316a59a7
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/sys/backtrace.rs:66:9
   3:        0x1180a68ec - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h026fb7f6a7f1ea39
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/sys/backtrace.rs:39:26
   4:        0x1180e5938 - core::fmt::rt::Argument::fmt::hbbdcec2d9d076bc0
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/core/src/fmt/rt.rs:177:76
   5:        0x1180e5938 - core::fmt::write::h91d8d0cf45debf6a
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/core/src/fmt/mod.rs:1189:21
   6:        0x11809babc - std::io::Write::write_fmt::h170ebb15403e2ed9
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/io/mod.rs:1884:15
   7:        0x1180a67a0 - std::sys::backtrace::BacktraceLock::print::h1c5c12d59c277afd
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/sys/backtrace.rs:42:9
   8:        0x1180a8b08 - std::panicking::default_hook::{{closure}}::h3fa22478e40098bd
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/panicking.rs:268:22
   9:        0x1180a8944 - std::panicking::default_hook::h929560e7fdb6dec1
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/panicking.rs:295:9
  10:        0x1180a9394 - std::panicking::rust_panic_with_hook::h74f0aa88ce9d76f1
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/panicking.rs:801:13
  11:        0x1180a8fe0 - std::panicking::begin_panic_handler::{{closure}}::hd7f7ba893f6d048a
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/panicking.rs:667:13
  12:        0x1180a6db0 - std::sys::backtrace::__rust_end_short_backtrace::hb30a0dde357a9afa
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/sys/backtrace.rs:170:18
  13:        0x1180a8cc0 - rust_begin_unwind
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/panicking.rs:665:5
  14:        0x118271e60 - core::panicking::panic_nounwind_fmt::runtime::h9a065bc8d9a43faa
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/core/src/panicking.rs:119:22
  15:        0x118271e60 - core::panicking::panic_nounwind_fmt::he9af3757db449dbb
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/core/src/intrinsics/mod.rs:3535:9
  16:        0x118271ed8 - core::panicking::panic_nounwind::h5913f439a043d9da
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/core/src/panicking.rs:223:5
  17:        0x118272050 - core::panicking::panic_cannot_unwind::h5d7baa6fc3483b98
                               at /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/core/src/panicking.rs:315:5
  18:        0x11350f92c - winit::platform_impl::ios::app_delegate::AppDelegate::will_terminate::hcd9f23c121eef92b
                               at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/objc2-0.5.2/src/macros/declare_class.rs:981:25
  19:        0x185aabf20 - -[UIApplication _terminateWithStatus:]
  20:        0x1850be5c0 - -[_UISceneLifecycleMultiplexer _evalTransitionToSettings:fromSettings:forceExit:withTransitionStore:]
  21:        0x1850be2b0 - -[_UISceneLifecycleMultiplexer forceExitWithTransitionContext:scene:]
  22:        0x185aa40b4 - -[UIApplication workspaceShouldExit:withTransitionContext:]
  23:        0x1879c1a20 - ___63-[FBSWorkspaceScenesClient willTerminateWithTransitionContext:]_block_invoke_2
  24:        0x1879a1618 - -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:]
  25:        0x1879c19c4 - ___63-[FBSWorkspaceScenesClient willTerminateWithTransitionContext:]_block_invoke
  26:        0x1028c67b8 - __dispatch_client_callout
  27:        0x1028ca3bc - __dispatch_block_invoke_direct
  28:        0x1879e4b58 - ___FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__
  29:        0x1879e4a34 - -[FBSMainRunLoopSerialQueue _targetQueue_performNextIfPossible]
  30:        0x1879e4b8c - -[FBSMainRunLoopSerialQueue _performNextFromRunLoopSource]
  31:        0x18041b324 - ___CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__
  32:        0x18041b26c - ___CFRunLoopDoSource0
  33:        0x18041aa2c - ___CFRunLoopDoSources0
  34:        0x1804150b0 - ___CFRunLoopRun
  35:        0x180414960 - _CFRunLoopRunSpecific
  36:        0x190183b10 - _GSEventRunModal
  37:        0x185aa2b40 - -[UIApplication _run]
  38:        0x185aa6d38 - _UIApplicationMain
  39:        0x1133ca058 - winit::platform_impl::ios::event_loop::EventLoop<T>::run::hb32ee7a1ec4b539d
                               at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/winit-0.30.5/src/platform_impl/ios/event_loop.rs:205:13
  40:        0x1133cfb90 - winit::event_loop::EventLoop<T>::run_app::h47f549c02e027760
                               at /Users/stephan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/winit-0.30.5/src/event_loop.rs:265:9
  41:        0x1133d7f68 - bevy_winit::state::winit_runner::h713374c3990bd02f
                               at /Users/stephan/code/bevy/crates/bevy_winit/src/state.rs:862:23
  42:        0x1133bfda4 - core::ops::function::FnOnce::call_once::hd61a07f3e1663185
                               at /Users/stephan/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  43:        0x1133bfa68 - core::ops::function::FnOnce::call_once{{vtable.shim}}::hc2396ec7c7c683df
                               at /Users/stephan/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  44:        0x117b9937c - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hbed70afc37825ae9
                               at /Users/stephan/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1972:9
  45:        0x117bac7cc - bevy_app::app::App::run::h40a86ddb5ba55d5c
                               at /Users/stephan/code/bevy/crates/bevy_app/src/app.rs:170:9
  46:        0x1133b0098 - bevy_mobile_example::main::hb78b8b72681b4e72
                               at /Users/stephan/code/bevy/examples/mobile/src/lib.rs:16:5
  47:        0x1133afc8c - main_rs
                               at /Users/stephan/code/bevy/examples/mobile/src/lib.rs:13:1
  48:        0x113386e48 - main
                               at /Users/stephan/code/bevy/examples/mobile/ios-src/main.m:4:5
thread caused non-unwinding panic. aborting.
Can't show file for stack frame : <DBGLLDBStackFrame: 0x36b6206f0> - stackNumber:3 - name:std::sys::pal::unix::abort_internal::hef23a7f1fbafab72. The file path does not exist on the file system: /rustc/9fc6b43126469e3858e2fe86cafb4f0fd5068869/library/std/src/sys/pal/unix/mod.rs

BUT on main it does not crash anymore.

[extrawurst]

@jmskov was it fixed in the meantime?

[jmskov]

I do observe it on 0.15.1 and 0.15.2, but not main. There must have been some changes or dependency upgrades in bevy_winit that fixed this issue on main.

I still observe a related error when I force quit the app before the window loop, but I think it's a winit-specific bug as it gives me a friendly message to file an issue with them.

[jmskov]

I think this is the fix that was incorporated into wgpu 0.24: gfx-rs/wgpu#6676

Edit: I see the first line of the error log references wgpu-core-23.0.1, so I am confident this case is fixed with the wgpu upgrade.

[alice-i-cecile]

Marking as fixed by #17542 :D