Wezterm: Crash on switching tabs

[chris-morgan]

Describe the bug

Switching to a different tab is consistently crashing.

Environment (please complete the following information):

• OS: Windows 10, build 19041.329
• Version: wezterm 20200620-160318-e00b076c-6-g076cf3d1

To Reproduce

1. Start WezTerm.
2. Click “+” to create a new tab.
3. Click on the first tab’s label.
4. Observe it crash.

Configuration

None.

Expected behavior

… not to crash! 😆

[wez]

Can you provide some more details on what you're seeing?
What is crashing? Is wezterm exiting? Is the tab immediately exiting, leaving wezterm running?
Can you try starting wezterm from a different console window so that you can capture its stderr output?

Please also share the output from running set in the initial console window (assuming that you are running cmd.exe; I'd like to see what the environment is set to).

[chris-morgan]

WezTerm exits.

Sorry, I removed the software from my machine because of these problems (and font rendering, a brief check looked like it wasn’t doing font fallbacks, which I rather want), and don’t feel like downloading and running it again. I might try it again at some point in the future, but not now.

[wez]

When you're ready to try again and work with me to get to the bottom of things, please open a new issue with more details!
I'm going to close this one because it doesn't seem like it will go anywhere with the information available right now.

[mborejdo]

@wez as I can reproduce the issue on Windows, what can I provide to track down the problem?

This is the stderr I see:

thread 'main' panicked at 'already mutably borrowed: BorrowError', /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\src\libcore\cell.rs:798:9 note: run withRUST_BACKTRACE=1environment variable to display a backtrace 2020-06-22T18:23:10.990Z ERROR window::os::windows::window > caught Any

Wezterm (wezterm 20200620-160318-e00b076c-6-g076cf3d) is crashing, And the window (with both tabs) disappearing.

[wez]

Ah interesting. To identify where this is coming from:

• Build a debug build from source cargo build (no --release)
• set RUST_BACKTRACE=1
• cargo run

It should then emit a pretty long stack trace; please share that here!

If you can't get the debug build working for whatever reason, the released build may still show something useful it you set RUST_BACKTRACE=1.

[mborejdo]

Thanks for repoening this

 2020-06-22T19:18:47.196Z ERROR wezterm::frontend::gui::termwindow > scale changed so resize to RowsAndCols { rows: 62, cols: 142 } Dimensions { pixel_width: 860, pixel_height: 764, dpi: 96 }
thread 'main' panicked at 'already mutably borrowed: BorrowError', /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\src\libcore\cell.rs:798:9
stack backtrace:
   0: backtrace::backtrace::trace_unsynchronized
             at C:\Users\VssAdministrator\.cargo\registry\src\github.com-1ecc6299db9ec823\backtrace-0.3.44\src\backtrace\mod.rs:66
   1: std::sys_common::backtrace::_print_fmt
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\sys_common\backtrace.rs:78
   2: std::sys_common::backtrace::_print::{{impl}}::fmt
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\sys_common\backtrace.rs:59
   3: core::fmt::write
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libcore\fmt\mod.rs:1063
   4: std::io::Write::write_fmt<std::sys::windows::stdio::Stderr>
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\io\mod.rs:1426
   5: std::sys_common::backtrace::_print
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\sys_common\backtrace.rs:62
   6: std::sys_common::backtrace::print
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\sys_common\backtrace.rs:49
   7: std::panicking::default_hook::{{closure}}
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\panicking.rs:204
   8: std::panicking::default_hook
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\panicking.rs:224
   9: std::panicking::rust_panic_with_hook
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\panicking.rs:474
  10: std::panicking::begin_panic_handler
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\panicking.rs:378
  11: core::panicking::panic_fmt
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libcore\panicking.rs:85
  12: core::option::expect_none_failed
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libcore\option.rs:1211
  13: wezterm::mux::Mux::get_window
  14: wezterm::frontend::gui::termwindow::TermWindow::set_viewport          15: wezterm::frontend::gui::termwindow::TermWindow::periodic_window_maintenance
  16: <dyn wezterm::frontend::gui::termwindow::ShapeCacheKeyTrait as core::cmp::PartialEq>::eq
  17: window::os::windows::window::do_wnd_proc
  18: std::panicking::try::do_call
  19: panic_unwind::__rust_maybe_catch_panic
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libpanic_unwind\lib.rs:86
  20: window::os::windows::window::do_wnd_proc
  21: CallWindowProcW
  22: CallWindowProcW
  23: glPushClientAttrib
  24: CallWindowProcW
  25: DispatchMessageW
  26: <window::os::windows::connection::Connection as window::connection::ConnectionOps>::run_message_loop
  27: wezterm::terminate_with_error
  28: wezterm::terminate_with_error
  29: std::io::Write::write_fmt
  30: std::rt::lang_start_internal::{{closure}}
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\rt.rs:52
  31: std::panicking::try::do_call<closure-0,i32>
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\panicking.rs:303
  32: panic_unwind::__rust_maybe_catch_panic
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libpanic_unwind\lib.rs:86
  33: std::panicking::try
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\panicking.rs:281
  34: std::panic::catch_unwind
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\panic.rs:394
  35: std::rt::lang_start_internal
             at /rustc/8d69840ab92ea7f4d323420088dd8c9775f180cd\/src\libstd\rt.rs:51
  36: main
  37: invoke_main
             at d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:78
  38: __scrt_common_main_seh
             at d:\agent\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288
  39: BaseThreadInitThunk
  40: RtlUserThreadStart
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
 2020-06-22T19:18:48.938Z ERROR window::os::windows::window        > caught Any

[wez]

Thanks; I believe that this is resolved by the commit referenced above!

[mborejdo]

I can confirm the referenced commit resolves the problem. Thanks!