Crash in release builds if I open a child window and close the main window

[nyanpasu64]

I'm running this repo, latest main d385acefcc2405ddb863f79e3ccdb4479891008c, on Linux.

If I cargo run --release, then click "Open in New Window" or "Show Other Window" (since they're non-modal), then close the main window with the child still open, the process will segfault.

• There is an inconsistent delay before the program crashes. In the case of "Show Other Window", the segfault happens after the "Call method on parent window" button is grayed out.
• The segfault does not occur on debug builds of Cargo+Flutter through cargo run. (I don't know how to control Rust and Flutter debugging separately.)

Stack trace is as follows (sadly it's a bit useless since libflutter_linux_gtk.so has no symbols):

``` (gdb) bt #0 0x00007ffff7dc5bf6 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #1 0x00007ffff7db5526 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #2 0x00007ffff7dc6705 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #3 0x00007ffff7f43934 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #4 0x00007ffff7b4bf29 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #5 0x00007ffff7c4ccb6 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #6 0x00007ffff7d56197 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #7 0x00007ffff7b26ee6 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #8 0x00007ffff7b25579 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #9 0x00007ffff7b3cb81 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #10 0x00007ffff768d073 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #11 0x00007ffff7692f46 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #12 0x00007ffff768cf11 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #13 0x00007ffff7692715 in () at /home/nyanpasu64/code/nativeshell-examples/target/release/lib/libflutter_linux_gtk.so #14 0x00007ffff6494259 in start_thread () at /usr/lib/libpthread.so.0 #15 0x00007ffff63b65e3 in clone () at /usr/lib/libc.so.6 ```

Flutter version:

Flutter 2.3.0-17.0.pre.412 • channel master • https://github.com/flutter/flutter.git Framework • revision 66b8f601e8 (62 minutes ago) • 2021-06-20 19:04:02 -0400 Engine • revision 1eb8a34a39 Tools • Dart 2.14.0 (build 2.14.0-228.0.dev)

System info:

Operating System: Arch Linux KDE Plasma Version: 5.22.1 KDE Frameworks Version: 5.83.0 Qt Version: 5.15.2 Kernel Version: 5.12.11-zen1-1-zen (64-bit) Graphics Platform: X11 Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor Memory: 15.6 GiB of RAM Graphics Processor: NVIDIA GeForce GT 730/PCIe/SSE2

[knopp]

Hi, this is a known issue, it is tracked here: https://github.com/flutter/flutter/issues/84908 The PR to fix it is being discussed here: https://github.com/flutter/engine/pull/26835