slint/internal/compiler/passes/binding_analysis.rs
Olivier Goffart db18f4e2e5 Change the new error that detects binding loop through the window into a warning
In 80de96488a (#3397) we introduced a new
error if we detect a binding loop from the Window geomerty to its layout.
But it looks like this causes a lot of error in existing project, so
make it a warning instead.

It will continue to be an error in the live preview as this will cause a
panic otherwise.

This commit also change the text of the error to include the actual
binding loop. I hope this makes it easier for users to see the loop and
help to fix it.
2025-06-02 19:01:47 +02:00

748 lines
29 KiB
Rust

// 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
//! Compute binding analysis and attempt to find binding loops
use std::collections::HashMap;
use std::collections::HashSet;
use std::rc::Rc;
use by_address::ByAddress;
use crate::diagnostics::{BuildDiagnostics, Spanned};
use crate::expression_tree::{BindingExpression, BuiltinFunction, Expression};
use crate::langtype::ElementType;
use crate::layout::{LayoutItem, Orientation};
use crate::namedreference::NamedReference;
use crate::object_tree::{find_parent_element, Document, ElementRc, PropertyAnimation};
use derive_more as dm;
use crate::expression_tree::Callable;
use crate::CompilerConfiguration;
use smol_str::{SmolStr, ToSmolStr};
/// Maps the alias in the other direction than what the BindingExpression::two_way_binding does.
/// So if binding for property A has B in its BindingExpression::two_way_binding, then
/// ReverseAliases maps B to A.
type ReverseAliases = HashMap<NamedReference, Vec<NamedReference>>;
pub fn binding_analysis(
doc: &Document,
compiler_config: &CompilerConfiguration,
diag: &mut BuildDiagnostics,
) {
let mut reverse_aliases = Default::default();
mark_used_base_properties(doc);
propagate_is_set_on_aliases(doc, &mut reverse_aliases);
perform_binding_analysis(
doc,
&reverse_aliases,
compiler_config.error_on_binding_loop_with_window_layout,
diag,
);
}
/// A reference to a property which might be deep in a component path.
/// eg: `foo.bar.baz.background`: `baz.background` is the `prop` and `foo` and `bar` are in elements
#[derive(Hash, PartialEq, Eq, Clone)]
struct PropertyPath {
elements: Vec<ByAddress<ElementRc>>,
prop: NamedReference,
}
impl std::fmt::Debug for PropertyPath {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
for e in &self.elements {
write!(f, "{}.", e.borrow().id)?;
}
self.prop.fmt(f)
}
}
impl PropertyPath {
/// Given a namedReference accessed by something on the same leaf component
/// as self, return a new PropertyPath that represent the property pointer
/// to by nr in the higher possible element
fn relative(&self, second: &PropertyPath) -> Self {
let mut element =
second.elements.first().map_or_else(|| second.prop.element(), |f| f.0.clone());
if element.borrow().enclosing_component.upgrade().unwrap().is_global() {
return second.clone();
}
let mut elements = self.elements.clone();
loop {
let enclosing = element.borrow().enclosing_component.upgrade().unwrap();
if enclosing.parent_element.upgrade().is_some()
|| !Rc::ptr_eq(&element, &enclosing.root_element)
{
break;
}
if let Some(last) = elements.pop() {
#[cfg(debug_assertions)]
fn check_that_element_is_in_the_component(
e: &ElementRc,
c: &Rc<crate::object_tree::Component>,
) -> bool {
let enclosing = e.borrow().enclosing_component.upgrade().unwrap();
Rc::ptr_eq(c, &enclosing)
|| enclosing
.parent_element
.upgrade()
.is_some_and(|e| check_that_element_is_in_the_component(&e, c))
}
#[cfg(debug_assertions)]
debug_assert!(
check_that_element_is_in_the_component(
&element,
last.borrow().base_type.as_component()
),
"The element is not in the component pointed at by the path ({self:?} / {second:?})"
);
element = last.0;
} else {
break;
}
}
if second.elements.is_empty() {
debug_assert!(elements.last().map_or(true, |x| *x != ByAddress(second.prop.element())));
Self { elements, prop: NamedReference::new(&element, second.prop.name().clone()) }
} else {
elements.push(ByAddress(element));
elements.extend(second.elements.iter().skip(1).cloned());
Self { elements, prop: second.prop.clone() }
}
}
}
impl From<NamedReference> for PropertyPath {
fn from(prop: NamedReference) -> Self {
Self { elements: vec![], prop }
}
}
#[derive(Default)]
struct AnalysisContext {
visited: HashSet<PropertyPath>,
/// The stack of properties that depends on each other
currently_analyzing: linked_hash_set::LinkedHashSet<PropertyPath>,
/// When set, one of the property in the `currently_analyzing` stack is the window layout property
/// And we should issue a warning if that's part of a loop instead of an error
window_layout_property: Option<PropertyPath>,
error_on_binding_loop_with_window_layout: bool,
}
fn perform_binding_analysis(
doc: &Document,
reverse_aliases: &ReverseAliases,
error_on_binding_loop_with_window_layout: bool,
diag: &mut BuildDiagnostics,
) {
let mut context =
AnalysisContext { error_on_binding_loop_with_window_layout, ..Default::default() };
doc.visit_all_used_components(|component| {
crate::object_tree::recurse_elem_including_sub_components_no_borrow(
component,
&(),
&mut |e, _| analyze_element(e, &mut context, reverse_aliases, diag),
)
});
}
fn analyze_element(
elem: &ElementRc,
context: &mut AnalysisContext,
reverse_aliases: &ReverseAliases,
diag: &mut BuildDiagnostics,
) {
for (name, binding) in &elem.borrow().bindings {
if binding.borrow().analysis.is_some() {
continue;
}
analyze_binding(
&PropertyPath::from(NamedReference::new(elem, name.clone())),
context,
reverse_aliases,
diag,
);
}
for cb in elem.borrow().change_callbacks.values() {
for e in cb.borrow().iter() {
recurse_expression(e, &mut |prop, r| {
process_property(prop, r, context, reverse_aliases, diag);
});
}
}
const P: ReadType = ReadType::PropertyRead;
for nr in elem.borrow().accessibility_props.0.values() {
process_property(&PropertyPath::from(nr.clone()), P, context, reverse_aliases, diag);
}
if let Some(g) = elem.borrow().geometry_props.as_ref() {
process_property(&g.x.clone().into(), P, context, reverse_aliases, diag);
process_property(&g.y.clone().into(), P, context, reverse_aliases, diag);
process_property(&g.width.clone().into(), P, context, reverse_aliases, diag);
process_property(&g.height.clone().into(), P, context, reverse_aliases, diag);
}
if let Some(component) = elem.borrow().enclosing_component.upgrade() {
if Rc::ptr_eq(&component.root_element, elem) {
for e in component.init_code.borrow().iter() {
recurse_expression(e, &mut |prop, r| {
process_property(prop, r, context, reverse_aliases, diag);
});
}
component.root_constraints.borrow_mut().visit_named_references(&mut |nr| {
process_property(&nr.clone().into(), P, context, reverse_aliases, diag);
});
component.popup_windows.borrow().iter().for_each(|p| {
process_property(&p.x.clone().into(), P, context, reverse_aliases, diag);
process_property(&p.y.clone().into(), P, context, reverse_aliases, diag);
});
component.timers.borrow().iter().for_each(|t| {
process_property(&t.interval.clone().into(), P, context, reverse_aliases, diag);
process_property(&t.running.clone().into(), P, context, reverse_aliases, diag);
process_property(&t.triggered.clone().into(), P, context, reverse_aliases, diag);
});
}
}
if let Some(repeated) = &elem.borrow().repeated {
recurse_expression(&repeated.model, &mut |prop, r| {
process_property(prop, r, context, reverse_aliases, diag);
});
if let Some(lv) = &repeated.is_listview {
process_property(&lv.viewport_y.clone().into(), P, context, reverse_aliases, diag);
process_property(&lv.viewport_height.clone().into(), P, context, reverse_aliases, diag);
process_property(&lv.viewport_width.clone().into(), P, context, reverse_aliases, diag);
process_property(&lv.listview_height.clone().into(), P, context, reverse_aliases, diag);
process_property(&lv.listview_width.clone().into(), P, context, reverse_aliases, diag);
}
}
if let Some((h, v)) = &elem.borrow().layout_info_prop {
process_property(&h.clone().into(), P, context, reverse_aliases, diag);
process_property(&v.clone().into(), P, context, reverse_aliases, diag);
}
}
#[derive(Copy, Clone, dm::BitAnd, dm::BitOr, dm::BitAndAssign, dm::BitOrAssign)]
struct DependsOnExternal(bool);
fn analyze_binding(
current: &PropertyPath,
context: &mut AnalysisContext,
reverse_aliases: &ReverseAliases,
diag: &mut BuildDiagnostics,
) -> DependsOnExternal {
let mut depends_on_external = DependsOnExternal(false);
let element = current.prop.element();
let name = current.prop.name();
if (context.currently_analyzing.back() == Some(current))
&& !element.borrow().bindings[name].borrow().two_way_bindings.is_empty()
{
let span = element.borrow().bindings[name]
.borrow()
.span
.clone()
.unwrap_or_else(|| element.borrow().to_source_location());
diag.push_error(format!("Property '{name}' cannot refer to itself"), &span);
return depends_on_external;
}
if context.currently_analyzing.contains(current) {
let mut loop_description = String::new();
let mut has_window_layout = false;
for it in context.currently_analyzing.iter().rev() {
if context.window_layout_property.as_ref().is_some_and(|p| p == it) {
has_window_layout = true;
}
if !loop_description.is_empty() {
loop_description.push_str(" -> ");
}
match it.prop.element().borrow().id.as_str() {
"" => loop_description.push_str(it.prop.name()),
id => {
loop_description.push_str(id);
loop_description.push_str(".");
loop_description.push_str(it.prop.name());
}
}
if it == current {
break;
}
}
for it in context.currently_analyzing.iter().rev() {
let p = &it.prop;
let elem = p.element();
let elem = elem.borrow();
let binding = elem.bindings[p.name()].borrow();
if binding.analysis.as_ref().unwrap().is_in_binding_loop.replace(true) {
break;
}
let span = binding.span.clone().unwrap_or_else(|| elem.to_source_location());
if !context.error_on_binding_loop_with_window_layout && has_window_layout {
diag.push_warning(format!("The binding for the property '{}' is part of a binding loop ({loop_description}).\nThis was allowed in previous version of Slint, but is deprecated and may cause panic at runtime", p.name()), &span);
} else {
diag.push_error(format!("The binding for the property '{}' is part of a binding loop ({loop_description})", p.name()), &span);
}
if it == current {
break;
}
}
return depends_on_external;
}
let binding = &element.borrow().bindings[name];
if binding.borrow().analysis.as_ref().is_some_and(|a| a.no_external_dependencies) {
return depends_on_external;
} else if !context.visited.insert(current.clone()) {
return DependsOnExternal(true);
}
if let Ok(mut b) = binding.try_borrow_mut() {
b.analysis = Some(Default::default());
};
context.currently_analyzing.insert(current.clone());
let b = binding.borrow();
for nr in &b.two_way_bindings {
if nr != &current.prop {
depends_on_external |= process_property(
&current.relative(&nr.clone().into()),
ReadType::PropertyRead,
context,
reverse_aliases,
diag,
);
}
}
let mut process_prop = |prop: &PropertyPath, r| {
depends_on_external |=
process_property(&current.relative(prop), r, context, reverse_aliases, diag);
for x in reverse_aliases.get(&prop.prop).unwrap_or(&Default::default()) {
if x != &current.prop && x != &prop.prop {
depends_on_external |= process_property(
&current.relative(&x.clone().into()),
ReadType::PropertyRead,
context,
reverse_aliases,
diag,
);
}
}
};
recurse_expression(&b.expression, &mut process_prop);
let mut is_const =
b.expression.is_constant() && b.two_way_bindings.iter().all(|n| n.is_constant());
if is_const && matches!(b.expression, Expression::Invalid) {
// check the base
if let Some(base) = element.borrow().sub_component() {
is_const = NamedReference::new(&base.root_element, name.clone()).is_constant();
}
}
drop(b);
if let Ok(mut b) = binding.try_borrow_mut() {
// We have a loop (through different component so we're still borrowed)
b.analysis.as_mut().unwrap().is_const = is_const;
}
match &binding.borrow().animation {
Some(PropertyAnimation::Static(e)) => analyze_element(e, context, reverse_aliases, diag),
Some(PropertyAnimation::Transition { animations, state_ref }) => {
recurse_expression(state_ref, &mut process_prop);
for a in animations {
analyze_element(&a.animation, context, reverse_aliases, diag);
}
}
None => (),
}
let o = context.currently_analyzing.pop_back();
assert_eq!(&o.unwrap(), current);
depends_on_external
}
#[derive(Copy, Clone, Eq, PartialEq)]
enum ReadType {
// Read from the native code
NativeRead,
// Read from another property binding in Slint
PropertyRead,
}
/// Process the property `prop`
///
/// This will visit all the bindings from that property
fn process_property(
prop: &PropertyPath,
read_type: ReadType,
context: &mut AnalysisContext,
reverse_aliases: &ReverseAliases,
diag: &mut BuildDiagnostics,
) -> DependsOnExternal {
let depends_on_external = match prop
.prop
.element()
.borrow()
.property_analysis
.borrow_mut()
.entry(prop.prop.name().clone())
.or_default()
{
a => {
if read_type == ReadType::PropertyRead {
a.is_read = true;
}
DependsOnExternal(prop.elements.is_empty() && a.is_set_externally)
}
};
let mut prop = prop.clone();
loop {
let element = prop.prop.element();
if element.borrow().bindings.contains_key(prop.prop.name()) {
analyze_binding(&prop, context, reverse_aliases, diag);
}
let next = match &element.borrow().base_type {
ElementType::Component(base) => {
if element.borrow().property_declarations.contains_key(prop.prop.name()) {
break;
}
base.root_element.clone()
}
ElementType::Builtin(builtin) => {
if builtin.properties.contains_key(prop.prop.name()) {
visit_builtin_property(builtin, &prop, context, reverse_aliases, diag);
}
break;
}
_ => break,
};
next.borrow()
.property_analysis
.borrow_mut()
.entry(prop.prop.name().clone())
.or_default()
.is_read_externally = true;
prop.elements.push(element.into());
prop.prop = NamedReference::new(&next, prop.prop.name().clone());
}
depends_on_external
}
// Same as in crate::visit_all_named_references_in_element, but not mut
fn recurse_expression(expr: &Expression, vis: &mut impl FnMut(&PropertyPath, ReadType)) {
const P: ReadType = ReadType::PropertyRead;
expr.visit(|sub| recurse_expression(sub, vis));
match expr {
Expression::PropertyReference(r) => vis(&r.clone().into(), P),
Expression::LayoutCacheAccess { layout_cache_prop, .. } => {
vis(&layout_cache_prop.clone().into(), P)
}
Expression::SolveLayout(l, o) | Expression::ComputeLayoutInfo(l, o) => {
// we should only visit the layout geometry for the orientation
if matches!(expr, Expression::SolveLayout(..)) {
if let Some(nr) = l.rect().size_reference(*o) {
vis(&nr.clone().into(), P);
}
}
match l {
crate::layout::Layout::GridLayout(l) => {
visit_layout_items_dependencies(l.elems.iter().map(|it| &it.item), *o, vis)
}
crate::layout::Layout::BoxLayout(l) => {
visit_layout_items_dependencies(l.elems.iter(), *o, vis)
}
}
let mut g = l.geometry().clone();
g.rect = Default::default(); // already visited;
g.visit_named_references(&mut |nr| vis(&nr.clone().into(), P))
}
Expression::FunctionCall {
function: Callable::Callback(nr) | Callable::Function(nr),
..
} => vis(&nr.clone().into(), P),
Expression::FunctionCall { function: Callable::Builtin(b), arguments, .. } => match b {
BuiltinFunction::ImplicitLayoutInfo(orientation) => {
if let [Expression::ElementReference(item)] = arguments.as_slice() {
visit_implicit_layout_info_dependencies(
*orientation,
&item.upgrade().unwrap(),
vis,
);
}
}
BuiltinFunction::ItemAbsolutePosition => {
if let Some(Expression::ElementReference(item)) = arguments.first() {
let mut item = item.upgrade().unwrap();
while let Some(parent) = find_parent_element(&item) {
item = parent;
vis(
&NamedReference::new(&item, SmolStr::new_static("x")).into(),
ReadType::NativeRead,
);
vis(
&NamedReference::new(&item, SmolStr::new_static("y")).into(),
ReadType::NativeRead,
);
}
}
}
BuiltinFunction::ItemFontMetrics => {
if let Some(Expression::ElementReference(item)) = arguments.first() {
let item = item.upgrade().unwrap();
vis(
&NamedReference::new(&item, SmolStr::new_static("font-size")).into(),
ReadType::NativeRead,
);
vis(
&NamedReference::new(&item, SmolStr::new_static("font-weight")).into(),
ReadType::NativeRead,
);
vis(
&NamedReference::new(&item, SmolStr::new_static("font-family")).into(),
ReadType::NativeRead,
);
vis(
&NamedReference::new(&item, SmolStr::new_static("font-italic")).into(),
ReadType::NativeRead,
);
}
}
_ => {}
},
_ => {}
}
}
fn visit_layout_items_dependencies<'a>(
items: impl Iterator<Item = &'a LayoutItem>,
orientation: Orientation,
vis: &mut impl FnMut(&PropertyPath, ReadType),
) {
for it in items {
let mut element = it.element.clone();
if element.borrow().repeated.as_ref().map(|r| recurse_expression(&r.model, vis)).is_some() {
element = it.element.borrow().base_type.as_component().root_element.clone();
}
if let Some(nr) = element.borrow().layout_info_prop(orientation) {
vis(&nr.clone().into(), ReadType::PropertyRead);
} else {
if let ElementType::Component(base) = &element.borrow().base_type {
if let Some(nr) = base.root_element.borrow().layout_info_prop(orientation) {
vis(
&PropertyPath {
elements: vec![ByAddress(element.clone())],
prop: nr.clone(),
},
ReadType::PropertyRead,
);
}
}
visit_implicit_layout_info_dependencies(orientation, &element, vis);
}
for (nr, _) in it.constraints.for_each_restrictions(orientation) {
vis(&nr.clone().into(), ReadType::PropertyRead)
}
}
}
/// The builtin function can call native code, and we need to visit the properties that are accessed by it
fn visit_implicit_layout_info_dependencies(
orientation: crate::layout::Orientation,
item: &ElementRc,
vis: &mut impl FnMut(&PropertyPath, ReadType),
) {
let base_type = item.borrow().base_type.to_smolstr();
const N: ReadType = ReadType::NativeRead;
match base_type.as_str() {
"Image" => {
vis(&NamedReference::new(item, SmolStr::new_static("source")).into(), N);
if orientation == Orientation::Vertical {
vis(&NamedReference::new(item, SmolStr::new_static("width")).into(), N);
}
}
"Text" | "TextInput" => {
vis(&NamedReference::new(item, SmolStr::new_static("text")).into(), N);
vis(&NamedReference::new(item, SmolStr::new_static("font-family")).into(), N);
vis(&NamedReference::new(item, SmolStr::new_static("font-size")).into(), N);
vis(&NamedReference::new(item, SmolStr::new_static("font-weight")).into(), N);
vis(&NamedReference::new(item, SmolStr::new_static("letter-spacing")).into(), N);
vis(&NamedReference::new(item, SmolStr::new_static("wrap")).into(), N);
let wrap_set = item.borrow().is_binding_set("wrap", false)
|| item
.borrow()
.property_analysis
.borrow()
.get("wrap")
.is_some_and(|a| a.is_set || a.is_set_externally);
if wrap_set && orientation == Orientation::Vertical {
vis(&NamedReference::new(item, SmolStr::new_static("width")).into(), N);
}
if base_type.as_str() == "TextInput" {
vis(&NamedReference::new(item, SmolStr::new_static("single-line")).into(), N);
} else {
vis(&NamedReference::new(item, SmolStr::new_static("overflow")).into(), N);
}
}
_ => (),
}
}
fn visit_builtin_property(
builtin: &crate::langtype::BuiltinElement,
prop: &PropertyPath,
context: &mut AnalysisContext,
reverse_aliases: &ReverseAliases,
diag: &mut BuildDiagnostics,
) {
let name = prop.prop.name();
if builtin.name == "Window" {
for (p, orientation) in
[("width", Orientation::Horizontal), ("height", Orientation::Vertical)]
{
if name == p {
// find the actual root component
let is_root = |e: &ElementRc| -> bool {
ElementRc::ptr_eq(
e,
&e.borrow().enclosing_component.upgrade().unwrap().root_element,
)
};
let mut root = prop.prop.element();
if !is_root(&root) {
return;
};
for e in prop.elements.iter().rev() {
if !is_root(&e.0) {
return;
}
root = e.0.clone();
}
if let Some(p) = root.borrow().layout_info_prop(orientation) {
let path = PropertyPath::from(p.clone());
let old_layout = context.window_layout_property.replace(path.clone());
process_property(&path, ReadType::NativeRead, context, reverse_aliases, diag);
context.window_layout_property = old_layout;
};
}
}
}
}
/// Make sure that the is_set property analysis is set to any property which has a two way binding
/// to a property that is, itself, is set
///
/// Example:
/// ```slint
/// Xx := TouchArea {
/// property <int> bar <=> foo;
/// clicked => { bar+=1; }
/// property <int> foo; // must ensure that this is not considered as const, because the alias with bar
/// }
/// ```
fn propagate_is_set_on_aliases(doc: &Document, reverse_aliases: &mut ReverseAliases) {
doc.visit_all_used_components(|component| {
crate::object_tree::recurse_elem_including_sub_components_no_borrow(
component,
&(),
&mut |e, _| visit_element(e, reverse_aliases),
);
});
fn visit_element(e: &ElementRc, reverse_aliases: &mut ReverseAliases) {
for (name, binding) in &e.borrow().bindings {
if !binding.borrow().two_way_bindings.is_empty() {
check_alias(e, name, &binding.borrow());
let nr = NamedReference::new(e, name.clone());
for a in &binding.borrow().two_way_bindings {
if a != &nr
&& !a.element().borrow().enclosing_component.upgrade().unwrap().is_global()
{
reverse_aliases.entry(a.clone()).or_default().push(nr.clone())
}
}
}
}
for decl in e.borrow().property_declarations.values() {
if let Some(alias) = &decl.is_alias {
mark_alias(alias)
}
}
}
fn check_alias(e: &ElementRc, name: &SmolStr, binding: &BindingExpression) {
// Note: since the analysis hasn't been run, any property access will result in a non constant binding. this is slightly non-optimal
let is_binding_constant =
binding.is_constant() && binding.two_way_bindings.iter().all(|n| n.is_constant());
if is_binding_constant && !NamedReference::new(e, name.clone()).is_externally_modified() {
for alias in &binding.two_way_bindings {
crate::namedreference::mark_property_set_derived_in_base(
alias.element(),
alias.name(),
);
}
return;
}
propagate_alias(binding);
}
fn propagate_alias(binding: &BindingExpression) {
for alias in &binding.two_way_bindings {
mark_alias(alias);
}
}
fn mark_alias(alias: &NamedReference) {
alias.mark_as_set();
if !alias.is_externally_modified() {
if let Some(bind) = alias.element().borrow().bindings.get(alias.name()) {
propagate_alias(&bind.borrow())
}
}
}
}
/// Make sure that the is_set_externally is true for all bindings.
/// And change bindings are used externally
fn mark_used_base_properties(doc: &Document) {
doc.visit_all_used_components(|component| {
crate::object_tree::recurse_elem_including_sub_components_no_borrow(
component,
&(),
&mut |element, _| {
if !matches!(element.borrow().base_type, ElementType::Component(_)) {
return;
}
for (name, binding) in &element.borrow().bindings {
if binding.borrow().has_binding() {
crate::namedreference::mark_property_set_derived_in_base(
element.clone(),
name,
);
}
}
for name in element.borrow().change_callbacks.keys() {
crate::namedreference::mark_property_read_derived_in_base(
element.clone(),
name,
);
}
},
);
});
}