assert when using `%` sizes in Flickable

[csavels]

Hello,

I'm having a problem compiling my Rust application after upgrading to Rust+Slint without modifying the code. I was using the "Slint 1.2" version before the update. Now the application no longer compiles and returns the error:

index.crates.io-6f17d22bba15001f/i-slint-compiler-1.3.2/passes/default_geometry.rs:281:9: assertion left == right failed left: Invalid right: LogicalLength

Config:

OS: macOS 14.1.1 (23B81) Language: Rust 1.74.1 Slint: 1.3.2 Slint-build : 1.3.2

What differences between the two versions could cause this? (app code is really too big to be shared).

Thanks already.

[tronical]

Thanks for the report - this looks indeed like a bug.

What differences between the two versions could cause this?

That's a good question...

This would happen if an element uses a percentage width or height binding (width: 30%;) and the parent has a width/height property that however has a type that's not length. I can't think of any built-in element that could cause this, nor can I reproduce it using an empty base or an attempt at overriding width/height.

Do you have any percentage width/height bindings? Could you check what the surrounding code looks like? (and paste it here, if possible - just an excerpt)

@ogoffart Do you have any idea what could cause this?

[ogoffart]

A lot changed in 1.3 with regards to height and width properties.

But it would be useful to have some code that reproduce the issue so we can debug it.

[ogoffart]

In order to be able to debug this issue, i'd need to access some code that reproduces the issue. Would you be able to share (even privately) that code?

[ian373]

@ogoffart I ran into the same error in slint 1.3.1, and here's an example to illustrate it:

• OS: win11 22H2
• rustc: 1.73.0 (cc66ad468 2023-10-03)

cargo.toml

[package]
name = "xxx"
version = "0.1.0"
edition = "2021"

[dependencies]
slint = "1.3.1"
[build-dependencies]
slint-build = "1.3.1"

main.rs

slint::include_modules!();

fn main() {
    MainWindow::new().unwrap().run().unwrap();
}

appwindow.slint

import { ListView } from "std-widgets.slint";
component ShowResult inherits Rectangle {
    width: 50%;
    height: 100%;

    VerticalLayout {
        ListView {
            for file[idx] in [1,2,3]:Rectangle {
                height: 20px;
                // width: parent.width;    // change to this line compiles fine
                width: 100%;  // An error occurred!!!
            }
        }
    }
}
export component MainWindow inherits Window {
    width: 326px;
    height: 326px;

    HorizontalLayout {
        width: 100%;
        height: 100%;

        ShowResult {}
    }
}

error:

[csavels]

Hello, Sorry for the delay in responding.

My UI is composed of more than 100 files, so it's hard to share, but my code is similar to the one copied as an example by "ian373".

Why does the percentage no longer work? Without the percentage, padding was ignored in previous versions of Slint, which is why I used it everywhere.

[csavels]

Another tip: the Slint preview is still working, but I can't compile the code.

stack backtrace: 0: 0x1037fca28 - std::backtrace_rs::backtrace::libunwind::trace::hf755a955ad018943 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5 1: 0x1037fca28 - std::backtrace_rs::backtrace::trace_unsynchronized::hde69ab8e2b667964 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 2: 0x1037fca28 - std::sys_common::backtrace::_print_fmt::hf6c414569af631f5 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/sys_common/backtrace.rs:67:5 3: 0x1037fca28 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h0524bd1b527203b8 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/sys_common/backtrace.rs:44:22 4: 0x103818818 - core::fmt::rt::Argument::fmt::ha0532872e39381ee at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/core/src/fmt/rt.rs:138:9 5: 0x103818818 - core::fmt::write::h74be1333b0a6ddea at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/core/src/fmt/mod.rs:1114:21 6: 0x1037f9e40 - std::io::Write::write_fmt::h6c011b665b2d7d4b at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/io/mod.rs:1763:15 7: 0x1037fc868 - std::sys_common::backtrace::_print::hcc60dadc0e4df78f at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/sys_common/backtrace.rs:47:5 8: 0x1037fc868 - std::sys_common::backtrace::print::he25ff7dac6402434 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/sys_common/backtrace.rs:34:9 9: 0x1037fde68 - std::panicking::default_hook::{{closure}}::h41763ba018b93bf7 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:272:22 10: 0x1037fdb80 - std::panicking::default_hook::h017c44660373840e at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:292:9 11: 0x1037fe3ac - std::panicking::rust_panic_with_hook::h221a0baf52ecd48a at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:731:13 12: 0x1037fe2b4 - std::panicking::begin_panic_handler::{{closure}}::h18b661cf0f97a414 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:609:13 13: 0x1037fceb4 - std::sys_common::backtrace::__rust_end_short_backtrace::h4f4b2ffab2311217 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/sys_common/backtrace.rs:170:18 14: 0x1037fe020 - rust_begin_unwind at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:597:5 15: 0x1038410d8 - core::panicking::panic_fmt::hd6070cd222575be5 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/core/src/panicking.rs:72:14 16: 0x103841460 - core::panicking::assert_failed_inner::h435b21d414fe4cfd 17: 0x10382e5e0 - core::panicking::assert_failed::h13d36bf8befbeaad 18: 0x102e4869c - i_slint_compiler::passes::default_geometry::fix_percent_size::h86c0b3ced87e365c 19: 0x102e44e18 - i_slint_compiler::passes::default_geometry::default_geometry::{{closure}}::hdeb9899c33a5a404 20: 0x10310d9bc - i_slint_compiler::object_tree::recurse_elem_including_sub_components::{{closure}}::h17839ccd085a1b09 21: 0x103109e64 - i_slint_compiler::object_tree::recurse_elem::h6a61c727bd4dd9fd 22: 0x103109f7c - i_slint_compiler::object_tree::recurse_elem::h6a61c727bd4dd9fd 23: 0x103109f7c - i_slint_compiler::object_tree::recurse_elem::h6a61c727bd4dd9fd 24: 0x103109f7c - i_slint_compiler::object_tree::recurse_elem::h6a61c727bd4dd9fd 25: 0x103109f7c - i_slint_compiler::object_tree::recurse_elem::h6a61c727bd4dd9fd 26: 0x103109f7c - i_slint_compiler::object_tree::recurse_elem::h6a61c727bd4dd9fd 27: 0x10310d2f0 - i_slint_compiler::object_tree::recurse_elem_including_sub_components::hf93c6269c417c6eb 28: 0x102e44d2c - i_slint_compiler::passes::default_geometry::default_geometry::h77d85cfa23428523 29: 0x102d3d978 - i_slint_compiler::passes::run_passes::{{closure}}::h0233a43448f892a3 30: 0x102d37edc - i_slint_compiler::compile_syntax_node::{{closure}}::h676fdd22b6e02281 31: 0x102d23594 - spin_on::spin_on::h36ca0e6873542373 32: 0x102d52720 - slint_build::compile_with_config::hcf3cd08b8fa2496a 33: 0x102d53744 - slint_build::compile::h753662bc80945ebc 34: 0x102d32978 - build_script_build::main::hd7ce96fed83b2854 35: 0x102d30a34 - core::ops::function::FnOnce::call_once::h5c998fdf23aa9f17 36: 0x102d40c4c - std::sys_common::backtrace::__rust_begin_short_backtrace::haa4cf23086652034 37: 0x102d34260 - std::rt::lang_start::{{closure}}::h7ecd142d863bbd44 38: 0x1037f4cd0 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::h44482c562109b08c at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/core/src/ops/function.rs:284:13 39: 0x1037f4cd0 - std::panicking::try::do_call::h627d61d518625eaf at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:504:40 40: 0x1037f4cd0 - std::panicking::try::h487b8df834773e7d at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:468:19 41: 0x1037f4cd0 - std::panic::catch_unwind::h5d4366c6f71d3443 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panic.rs:142:14 42: 0x1037f4cd0 - std::rt::lang_start_internal::{{closure}}::h749338e1cc06c4f7 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/rt.rs:148:48 43: 0x1037f4cd0 - std::panicking::try::do_call::h2098bd254e5cae95 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:504:40 44: 0x1037f4cd0 - std::panicking::try::h7bfd8a0246bca0f8 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panicking.rs:468:19 45: 0x1037f4cd0 - std::panic::catch_unwind::h6da51257cc975c65 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/panic.rs:142:14 46: 0x1037f4cd0 - std::rt::lang_start_internal::h5f00c09289a72e67 at /rustc/a28077b28a02b92985b3a3faecf92813155f1ea1/library/std/src/rt.rs:148:20 47: 0x102d3423c - std::rt::lang_start::h297d850e9d95d25d 48: 0x102d329b8 - _main

[ogoffart]

It works with the preview because this is a debug_assert failing and the preview is compiled in release.

The failling code can be reduced to this:

  Flickable { Rectangle { width: 100% } }

What should the 100% be relative to? To the viewport or to the flickable? parent.width is relative to the flickabled But by the time we try to compute the size of 100%, there is a viewport inbetween. The assert is

debug_assert_eq!(
            parent.borrow().lookup_property(property).property_type,
            Type::LogicalLength
        );

And this fails for the Flickable viewport because lookup_property does't check the reserved builtin property for a ElementType::Native (which the viewport is)

[csavels]

Hello,

I modified all my pages this morning (outch!) and now it works. I've removed all use of a percentage and replaced it with "parent.length - padding". I'll never use the percentage again to avoid problems. Thanks for your help.