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LibWeb: Drop the needs_inset_resolution layout callback #11092

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Merged
kalenikaliaksandr merged 1 commit into from
Aug 11, 2026
+11 −19
Merged

LibWeb: Drop the needs_inset_resolution layout callback #11092

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6 changes: 0 additions & 6 deletions Libraries/LibWeb/Layout/LayoutRustBridge.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1118,12 +1118,6 @@ RustFFI::FfiLayoutFcCallbacks LayoutRustBridge::formatting_context_callbacks()
.arena = m_commit_root->arena_handle(),
.initial_containing_block_inline_size = m_commit_root->document().viewport_rect().width().raw_value(),
.document_in_quirks_mode = m_commit_root->document().in_quirks_mode(),
.needs_inset_resolution = [](void*, void* node) {
auto const& styled_node = *static_cast<NodeWithStyle const*>(node);
if (styled_node.computed_values().position() == CSS::Positioning::Relative)
return true;
auto const* box = as_if<Box>(styled_node);
return box && box_inset_properties_contain_anchor_functions(*box); },
.report_unexpected_fragmented_inline = [](void*, void* node) {
auto const& box = *static_cast<Box const*>(node);
dbgln("FIXME: InlineFormattingContext::dimension_box_on_line got unexpected box in inline context:");
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23 changes: 11 additions & 12 deletions Libraries/LibWeb/Rust/src/layout/abspos_engine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1805,25 +1805,24 @@ impl AbsposEngine {
treat_block_axis_percentage_insets_as_auto_beyond_root: bool,
) {
// Most boxes are neither relatively positioned nor carry anchor()
// insets. Preserve the old C++ fast path without populating the
// comprehensive Rust facts caches for those boxes.
// SAFETY: The callback only reads the live node's computed values.
if !unsafe {
(self.callbacks.needs_inset_resolution)(self.callbacks.context, self.callbacks.shell(node))
} {
return;
}
// insets, and both facts come straight from the node's style payload.
let initial_style = self.style(node);
let resolved = if initial_style.inset_top().contains_anchor_function()
let has_anchor_insets = initial_style.inset_top().contains_anchor_function()
|| initial_style.inset_right().contains_anchor_function()
|| initial_style.inset_bottom().contains_anchor_function()
|| initial_style.inset_left().contains_anchor_function()
{
|| initial_style.inset_left().contains_anchor_function();
if !has_anchor_insets && initial_style.position() != positioning::RELATIVE {
return;
}
// Anchor resolution also refreshes the box's default scroll shift, so
// an anchor-bearing box resolves its insets even when it turns out not
// to be relatively positioned.
let resolved = if has_anchor_insets {
self.resolve_anchor_insets(node, None, NodeSlotId::INVALID)
} else {
Comment on lines +1814 to 1822

@coderabbitai coderabbitai Bot Aug 11, 2026

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🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Preserve stale scroll-shift cleanup for relative nodes.

When a relative node has no anchor() inset, this branch skips resolve_anchor_insets. That helper clears the existing default scroll shift before checking for anchor insets at Lines 558-568. If a node changes from anchor-bearing to ordinary relative positioning, stale scroll-shift state can remain and produce incorrect layout.

Keep the early return for nodes that are neither relative nor anchor-bearing, but call resolve_anchor_insets for every node that passes that gate.

Proposed fix 
-        let resolved = if has_anchor_insets {
-            self.resolve_anchor_insets(node, None, NodeSlotId::INVALID)
-        } else {
-            None
-        };
+        let resolved = self.resolve_anchor_insets(node, None, NodeSlotId::INVALID);
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
if !has_anchor_insets && initial_style.position() != positioning::RELATIVE {
return;
}
// Anchor resolution also refreshes the box's default scroll shift, so
// an anchor-bearing box resolves its insets even when it turns out not
// to be relatively positioned.
let resolved = if has_anchor_insets {
self.resolve_anchor_insets(node, None, NodeSlotId::INVALID)
} else {
if !has_anchor_insets && initial_style.position() != positioning::RELATIVE {
return;
}
// Anchor resolution also refreshes the box's default scroll shift, so
// an anchor-bearing box resolves its insets even when it turns out not
// to be relatively positioned.
let resolved = self.resolve_anchor_insets(node, None, NodeSlotId::INVALID);
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@Libraries/LibWeb/Rust/src/layout/abspos_engine.rs` around lines 1814 - 1822,
Update the early-return flow in the relative-positioning logic so nodes that are
relative, including those without anchor insets, always call
resolve_anchor_insets. Retain the early return only when the node is neither
relative nor anchor-bearing, ensuring stale default scroll-shift state is
cleared for ordinary relative nodes.

None
};
let style = self.style(node).with_resolved_insets(resolved.as_ref());
let style = initial_style.with_resolved_insets(resolved.as_ref());
if style.position() != positioning::RELATIVE {
return;
}
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1 change: 0 additions & 1 deletion Libraries/LibWeb/Rust/src/layout/formatting_context.rs
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Expand Up @@ -936,7 +936,6 @@ pub struct FfiLayoutFcCallbacks {
pub arena: *mut c_void,
pub initial_containing_block_inline_size: CssPixels,
pub document_in_quirks_mode: bool,
pub needs_inset_resolution: unsafe extern "C" fn(*mut c_void, *mut c_void) -> bool,
pub report_unexpected_fragmented_inline: unsafe extern "C" fn(*mut c_void, *mut c_void),
pub build_svg_facts: unsafe extern "C" fn(*mut c_void, *mut c_void) -> FfiSvgElementFacts,
pub read_paintable_geometry:
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