Cells example panics at 'already mutably borrowed: BorrowError'

[airstrike]

Hi, I'm running Mac OS 14.2.1 and trying to run the cells example in the examples folder.

The example loads after building (in a tiny window that I can resize) and it continues to load fine after typing in numbers into cells. I'm even able to type 1+2 and see the result 3.

However, when I try to type a non-numeric character as the first character in a cell—such as =, ( or a—the program crashes with thread 'main' panicked at 'already mutably borrowed: BorrowError', examples/7guis/cells.rs:124:27

I first ran the example with $ SLINT_NO_QT=1 cargo run --release --bin cells which caused the crash

Below is the full output of $ RUST_BACKTRACE=full SLINT_NO_QT=1 cargo run --bin cells

warning: Component is neither used nor exported
  --> /Users/andy/projects/slint/examples/7guis/cells.slint:77:1
   |
77 | component Cell inherits MainWindow {
   | ^

    Finished dev [unoptimized + debuginfo] target(s) in 0.16s
     Running `/Users/andy/projects/slint/target/debug/cells`
thread 'main' panicked at 'already mutably borrowed: BorrowError', examples/7guis/cells.rs:124:27
stack backtrace:
   0:        0x100731a04 - std::backtrace_rs::backtrace::libunwind::trace::h65bc41667b946a9b
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:        0x100731a04 - std::backtrace_rs::backtrace::trace_unsynchronized::h11e85e00c64d2951
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:        0x100731a04 - std::sys_common::backtrace::_print_fmt::hd30f3b7be3b8d9bb
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/sys_common/backtrace.rs:65:5
   3:        0x100731a04 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h56d7672c82815b65
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/sys_common/backtrace.rs:44:22
   4:        0x10074d094 - core::fmt::rt::Argument::fmt::h6ead82aa10d38e42
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/fmt/rt.rs:138:9
   5:        0x10074d094 - core::fmt::write::h632b3cc8e66b4f04
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/fmt/mod.rs:1094:21
   6:        0x10072f4d0 - std::io::Write::write_fmt::hc28441b249a4971d
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/io/mod.rs:1714:15
   7:        0x10073185c - std::sys_common::backtrace::_print::h0d2f8b8a08c5cc48
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/sys_common/backtrace.rs:47:5
   8:        0x10073185c - std::sys_common::backtrace::print::h8057ced4b0f9fdc1
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/sys_common/backtrace.rs:34:9
   9:        0x100732c1c - std::panicking::default_hook::{{closure}}::h8157fa8f0f7934b5
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/panicking.rs:269:22
  10:        0x1007329ac - std::panicking::default_hook::hdaefe3bfb5fe212c
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/panicking.rs:288:9
  11:        0x10073314c - std::panicking::rust_panic_with_hook::h21091a3c79c5da9c
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/panicking.rs:705:13
  12:        0x100733058 - std::panicking::begin_panic_handler::{{closure}}::hd2f65b958d3068b8
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/panicking.rs:597:13
  13:        0x100731de4 - std::sys_common::backtrace::__rust_end_short_backtrace::h53ec33e49ec66621
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/sys_common/backtrace.rs:151:18
  14:        0x100732dc4 - rust_begin_unwind
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/panicking.rs:593:5
  15:        0x10076b780 - core::panicking::panic_fmt::h3bbf9265d206434c
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/panicking.rs:67:14
  16:        0x10076bb40 - core::result::unwrap_failed::h1cd46f955b5f93b7
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/result.rs:1651:5
  17:        0x10008a5f4 - core::result::Result<T,E>::expect::h8a2a0fe5ac9126c4
                               at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/result.rs:1033:23
[1]    62930 abort      RUST_BACKTRACE=full SLINT_NO_QT=1 cargo run --bin cells

[ogoffart]

Thanks a lot for reporting the bug.
Should be fixed with commit ca881ea
We just were holding on a borrow_mut for too long.