Re-land: fixYogaFlexBasisFitContentInMainAxis#1917
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Summary: X-link: react/yoga#1917 Re-land of D94658492 with fixes, which was reverted in D95669495. ## Context D94658492 added the `fixYogaFlexBasisFitContentInMainAxis` flag to avoid unnecessary re-measurement cascades in Yoga. When Yoga computes flex basis for container children, the legacy behavior applies a `FitContent` constraint in the main axis, bounding the child's measurement by the parent's available space. This creates a dependency between the child's flex basis and the parent's content-determined size — when one sibling changes size, all siblings get re-measured and their shadow nodes get cloned unnecessarily. The fix switches from `FitContent` to `MaxContent` for non-measure container children under auto-height parents, making each child's flex basis independent of the parent's size. ## What went wrong D94658492 modeled the fix as a `YogaErrata` bit (`FLEX_BASIS_FIT_CONTENT_IN_MAIN_AXIS`). Errata flags are bitmasks, and apps that opt into `ALL` or `CLASSIC` errata (like IGVR and Airwave) inadvertently picked up the new behavior without explicitly enabling the feature flag, causing breakages. ## What changed in this re-land This diff models the fix as a `YogaExperimentalFeature` (`FIX_FLEX_BASIS_FIT_CONTENT`) instead of a `YogaErrata` bit. Experimental features are individually opt-in, so existing apps won't accidentally pick up the change. This diff only wires up the RN feature flag infrastructure (flag defaults to `false`). The iOS MobileConfig override and the Yoga layout logic will be landed in follow-up diffs. changelog: [internal] Reviewed By: javache Differential Revision: D95852922
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Summary: X-link: react/react-native#56064 Re-land of D94658492 with fixes, which was reverted in D95669495. ## Context D94658492 added the `fixYogaFlexBasisFitContentInMainAxis` flag to avoid unnecessary re-measurement cascades in Yoga. When Yoga computes flex basis for container children, the legacy behavior applies a `FitContent` constraint in the main axis, bounding the child's measurement by the parent's available space. This creates a dependency between the child's flex basis and the parent's content-determined size — when one sibling changes size, all siblings get re-measured and their shadow nodes get cloned unnecessarily. The fix switches from `FitContent` to `MaxContent` for non-measure container children under auto-height parents, making each child's flex basis independent of the parent's size. ## What went wrong D94658492 modeled the fix as a `YogaErrata` bit (`FLEX_BASIS_FIT_CONTENT_IN_MAIN_AXIS`). Errata flags are bitmasks, and apps that opt into `ALL` or `CLASSIC` errata (like IGVR and Airwave) inadvertently picked up the new behavior without explicitly enabling the feature flag, causing breakages. ## What changed in this re-land This diff models the fix as a `YogaExperimentalFeature` (`FIX_FLEX_BASIS_FIT_CONTENT`) instead of a `YogaErrata` bit. Experimental features are individually opt-in, so existing apps won't accidentally pick up the change. This diff only wires up the RN feature flag infrastructure (flag defaults to `false`). The iOS MobileConfig override and the Yoga layout logic will be landed in follow-up diffs. changelog: [internal] Reviewed By: javache Differential Revision: D95852922
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Summary: X-link: react/yoga#1917 Re-land of D94658492 with fixes, which was reverted in D95669495. ## Context D94658492 added the `fixYogaFlexBasisFitContentInMainAxis` flag to avoid unnecessary re-measurement cascades in Yoga. When Yoga computes flex basis for container children, the legacy behavior applies a `FitContent` constraint in the main axis, bounding the child's measurement by the parent's available space. This creates a dependency between the child's flex basis and the parent's content-determined size — when one sibling changes size, all siblings get re-measured and their shadow nodes get cloned unnecessarily. The fix switches from `FitContent` to `MaxContent` for non-measure container children under auto-height parents, making each child's flex basis independent of the parent's size. ## What went wrong D94658492 modeled the fix as a `YogaErrata` bit (`FLEX_BASIS_FIT_CONTENT_IN_MAIN_AXIS`). Errata flags are bitmasks, and apps that opt into `ALL` or `CLASSIC` errata (like IGVR and Airwave) inadvertently picked up the new behavior without explicitly enabling the feature flag, causing breakages. ## What changed in this re-land This diff models the fix as a `YogaExperimentalFeature` (`FIX_FLEX_BASIS_FIT_CONTENT`) instead of a `YogaErrata` bit. Experimental features are individually opt-in, so existing apps won't accidentally pick up the change. This diff only wires up the RN feature flag infrastructure (flag defaults to `false`). The iOS MobileConfig override and the Yoga layout logic will be landed in follow-up diffs. changelog: [internal] Reviewed By: javache Differential Revision: D95852922
Summary: X-link: react/react-native#56064 Re-land of D94658492 with fixes, which was reverted in D95669495. ## Context D94658492 added the `fixYogaFlexBasisFitContentInMainAxis` flag to avoid unnecessary re-measurement cascades in Yoga. When Yoga computes flex basis for container children, the legacy behavior applies a `FitContent` constraint in the main axis, bounding the child's measurement by the parent's available space. This creates a dependency between the child's flex basis and the parent's content-determined size — when one sibling changes size, all siblings get re-measured and their shadow nodes get cloned unnecessarily. The fix switches from `FitContent` to `MaxContent` for non-measure container children under auto-height parents, making each child's flex basis independent of the parent's size. ## What went wrong D94658492 modeled the fix as a `YogaErrata` bit (`FLEX_BASIS_FIT_CONTENT_IN_MAIN_AXIS`). Errata flags are bitmasks, and apps that opt into `ALL` or `CLASSIC` errata (like IGVR and Airwave) inadvertently picked up the new behavior without explicitly enabling the feature flag, causing breakages. ## What changed in this re-land This diff models the fix as a `YogaExperimentalFeature` (`FIX_FLEX_BASIS_FIT_CONTENT`) instead of a `YogaErrata` bit. Experimental features are individually opt-in, so existing apps won't accidentally pick up the change. This diff only wires up the RN feature flag infrastructure (flag defaults to `false`). The iOS MobileConfig override and the Yoga layout logic will be landed in follow-up diffs. changelog: [internal] Reviewed By: javache, NickGerleman Differential Revision: D95852922
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Summary: X-link: react/yoga#1917 Re-land of D94658492 with fixes, which was reverted in D95669495. ## Context D94658492 added the `fixYogaFlexBasisFitContentInMainAxis` flag to avoid unnecessary re-measurement cascades in Yoga. When Yoga computes flex basis for container children, the legacy behavior applies a `FitContent` constraint in the main axis, bounding the child's measurement by the parent's available space. This creates a dependency between the child's flex basis and the parent's content-determined size — when one sibling changes size, all siblings get re-measured and their shadow nodes get cloned unnecessarily. The fix switches from `FitContent` to `MaxContent` for non-measure container children under auto-height parents, making each child's flex basis independent of the parent's size. ## What went wrong D94658492 modeled the fix as a `YogaErrata` bit (`FLEX_BASIS_FIT_CONTENT_IN_MAIN_AXIS`). Errata flags are bitmasks, and apps that opt into `ALL` or `CLASSIC` errata (like IGVR and Airwave) inadvertently picked up the new behavior without explicitly enabling the feature flag, causing breakages. ## What changed in this re-land This diff models the fix as a `YogaExperimentalFeature` (`FIX_FLEX_BASIS_FIT_CONTENT`) instead of a `YogaErrata` bit. Experimental features are individually opt-in, so existing apps won't accidentally pick up the change. This diff only wires up the RN feature flag infrastructure (flag defaults to `false`). The iOS MobileConfig override and the Yoga layout logic will be landed in follow-up diffs. changelog: [internal] Reviewed By: javache, NickGerleman Differential Revision: D95852922
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Summary: Pull Request resolved: #56064 X-link: react/yoga#1917 Re-land of D94658492 with fixes, which was reverted in D95669495. ## Context D94658492 added the `fixYogaFlexBasisFitContentInMainAxis` flag to avoid unnecessary re-measurement cascades in Yoga. When Yoga computes flex basis for container children, the legacy behavior applies a `FitContent` constraint in the main axis, bounding the child's measurement by the parent's available space. This creates a dependency between the child's flex basis and the parent's content-determined size — when one sibling changes size, all siblings get re-measured and their shadow nodes get cloned unnecessarily. The fix switches from `FitContent` to `MaxContent` for non-measure container children under auto-height parents, making each child's flex basis independent of the parent's size. ## What went wrong D94658492 modeled the fix as a `YogaErrata` bit (`FLEX_BASIS_FIT_CONTENT_IN_MAIN_AXIS`). Errata flags are bitmasks, and apps that opt into `ALL` or `CLASSIC` errata (like IGVR and Airwave) inadvertently picked up the new behavior without explicitly enabling the feature flag, causing breakages. ## What changed in this re-land This diff models the fix as a `YogaExperimentalFeature` (`FIX_FLEX_BASIS_FIT_CONTENT`) instead of a `YogaErrata` bit. Experimental features are individually opt-in, so existing apps won't accidentally pick up the change. This diff only wires up the RN feature flag infrastructure (flag defaults to `false`). The iOS MobileConfig override and the Yoga layout logic will be landed in follow-up diffs. changelog: [internal] Reviewed By: javache, NickGerleman Differential Revision: D95852922 fbshipit-source-id: e2b1aa7a5d8f340011123679f721c62396b5caa5
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Summary:
Re-land of D94658492 with fixes, which was reverted in D95669495.
Context
D94658492 added the
fixYogaFlexBasisFitContentInMainAxisflag to avoid unnecessary re-measurement cascades in Yoga. When Yoga computes flex basis for container children, the legacy behavior applies aFitContentconstraint in the main axis, bounding the child's measurement by the parent's available space. This creates a dependency between the child's flex basis and the parent's content-determined size — when one sibling changes size, all siblings get re-measured and their shadow nodes get cloned unnecessarily.The fix switches from
FitContenttoMaxContentfor non-measure container children under auto-height parents, making each child's flex basis independent of the parent's size.What went wrong
D94658492 modeled the fix as a
YogaErratabit (FLEX_BASIS_FIT_CONTENT_IN_MAIN_AXIS). Errata flags are bitmasks, and apps that opt intoALLorCLASSICerrata (like IGVR and Airwave) inadvertently picked up the new behavior without explicitly enabling the feature flag, causing breakages.What changed in this re-land
This diff models the fix as a
YogaExperimentalFeature(FIX_FLEX_BASIS_FIT_CONTENT) instead of aYogaErratabit. Experimental features are individually opt-in, so existing apps won't accidentally pick up the change.This diff only wires up the RN feature flag infrastructure (flag defaults to
false). The iOS MobileConfig override and the Yoga layout logic will be landed in follow-up diffs.changelog: [internal]
Reviewed By: javache
Differential Revision: D95852922