panicked at 'invalid expression while evaluating'

[jturcotte]

export Test := VerticalLayout {
    spacing: 1px;

    HorizontalLayout {
        Rectangle {
            // At first I didn't see that there was an HorizontalLayout in-between in the original code.
            width: parent.height - parent.spacing;
        }
    }
}

This is with slint-viewer/slint-lsp 0.3.5, I tried it in the 1.0 SlintPad and it seems to panic there as well.

[tronical]

AFAICS it's the parent.spacing that somehow turns into a Expression::Invalid and in the phase lowering to the LLR that panics (since Invalid is kind of hard to lower ;-)

When lowering the binding for width:

        tree_Expression::BinaryExpression { lhs, rhs, op } => llr_Expression::BinaryExpression {
            lhs: Box::new(lower_expression(lhs, ctx)),
            rhs: Box::new(lower_expression(rhs, ctx)), <-- rhs is Expression::Invalid
            op: *op,
        },

[ogoffart]

The viewer and LSP don't lower to LLR, this is probably in the eval phase of the interpreter. But if the LLR makes invalid code, this probably fails for the same reason.

[tronical]

Yes, the above is with slint-compiler, but with the interpreter it's exactly the same:

        Expression::BinaryExpression { lhs, rhs, op } => {
            let lhs = eval_expression(&**lhs, local_context);
            let rhs = eval_expression(&**rhs, local_context); <-- rhs is invalid