slint/internal/compiler/passes/check_expressions.rs

// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0

use std::rc::Rc;

use crate::diagnostics::BuildDiagnostics;
use crate::expression_tree::{BuiltinFunction, Callable, Expression};
use crate::object_tree::{visit_all_expressions, Component};

/// Check the validity of expressions
///
/// - Check that the GetWindowScaleFactor and GetWindowDefaultFontSize are not called in a global
pub fn check_expressions(doc: &crate::object_tree::Document, diag: &mut BuildDiagnostics) {
    for component in &doc.inner_components {
        visit_all_expressions(component, |e, _| check_expression(component, e, diag));
    }
}

fn check_expression(component: &Rc<Component>, e: &Expression, diag: &mut BuildDiagnostics) {
    if let Expression::FunctionCall { function: Callable::Builtin(b), source_location, .. } = e {
        match b {
            BuiltinFunction::GetWindowScaleFactor => {
                if component.is_global() {
                    diag.push_error("Cannot convert between logical and physical length in a global component, because the scale factor is not known".into(), source_location);
                }
            }
            BuiltinFunction::GetWindowDefaultFontSize => {
                if component.is_global() {
                    diag.push_error("Cannot convert between rem and logical length in a global component, because the default font size is not known".into(), source_location);
                }
            }
            _ => {}
        }
    }
    e.visit(|e| check_expression(component, e, diag))
}