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react-native/scripts
Jakub Piasecki 2546ce4d82 Fix display: contents nodes having hasNewLayout set incorrectly (#57103)
Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/57103

Changelog: [General][Fixed] Fixed `display: contents` nodes having `hasNewLayout` set incorrectly

`cleanupContentsNodesRecursively` unconditionally sets `hasNewLayout=true` on `display: contents` children, including on code paths where their parent's layout was not actually performed in this pass. The stale flag can survive across layout passes and, in clone-on-write renderers (e.g. React Native Fabric), be observed by a subsequent pass whose parent was cloned but whose layout was served from cache, leaving the contents child's owner pointing at the previous parent revision.

There are two paths through which the cleanup could stamp a contents child whose parent's `hasNewLayout` would end up false:

1. Measure-phase visit. Inside `calculateLayoutImpl`, the cleanup ran with no knowledge of `performLayout`. When the parent's `calculateLayoutImpl` was invoked only with `performLayout=false` (cache miss on measure, cache hit on layout), the cleanup stamped contents children even though the parent itself never had its `hasNewLayout` set.

2. Absolute-layout walk. `layoutAbsoluteDescendants` walks every static layout descendant of the containing block - including ones whose own `calculateLayoutImpl` was skipped via the layout-phase cache. The cleanup invoked along that walk unconditionally stamped contents children, but the parent's `hasNewLayout` was only updated when the recursion actually found new layout downstream.

In both cases, the result is the same invariant violation: a contents node with `hasNewLayout=true` whose parent has `hasNewLayout=false`. A consumer iterating the tree via `hasNewLayout` skips the parent and never clears the stale flag.

X-link: https://github.com/facebook/yoga/pull/1970

Test Plan:
Added `YGContentsNodeHasNewLayoutTest.cpp` with regression tests:
- `contents_child_hasNewLayout_not_stamped_on_measure_only_visit` - pins the measure-phase fix
- `absolute_descendant_through_contents_is_reachable_via_hasNewLayout` - pins the positive case for absolute-layout path
- `absolute_phase_cleanup_does_not_stamp_when_parent_layout_skipped` - pins the negative case for absolute-layout path

Reviewed By: javache

Differential Revision: D107854528

Pulled By: j-piasecki

fbshipit-source-id: cae5e889622296e8b6380a6428509b5ffea3e9ae
2026-06-08 07:49:55 -07:00
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