fix: prevent crash in SurfaceListModel::data when accessing childItem…

[zorowk]

…s too early

Add null checks for surface->parentItem() and container before calling container->childItems().indexOf(surface). This avoids dereferencing an incompletely initialized QQuickItem when a new surface is added to the model but has not yet been fully inserted into the scene graph.

Returning INT_MAX as a fallback sort order places unready surfaces at the end of the list, ensuring stable behavior until the item is properly parented and polished.

issue: #659
comment: #659 (comment)

Summary by Sourcery

Bug Fixes:

• Prevent a crash in SurfaceListModel::data by handling cases where a surface has no parent item or container during initial sort order calculation.

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: zorowk

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[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Adds defensive null checks in SurfaceListModel::data for the InitialSortOrderRole to avoid dereferencing incompletely initialized QQuickItem instances, and falls back to INT_MAX as the sort order for surfaces whose parent/container is not yet ready.

Class diagram for updated SurfaceListModel::data null-check behavior

classDiagram
    class SurfaceListModel {
        +data(index QModelIndex, role int) QVariant
        +surfaces() QList~Surface*~
    }

    class Surface {
        +parentItem() QQuickItem*
        +container() QQuickItem*
    }

    class QQuickItem {
        +childItems() QList~QQuickItem*~
    }

    class QModelIndex
    class QVariant

    SurfaceListModel --> Surface : uses
    Surface --> QQuickItem : parentItem
    Surface --> QQuickItem : container
    QQuickItem --> QQuickItem : childItems
    SurfaceListModel --> QModelIndex : parameter
    SurfaceListModel --> QVariant : return type

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File-Level Changes

Change	Details	Files
Harden SurfaceListModel::data against partially initialized surfaces when computing InitialSortOrderRole, falling back to a max-int sort order for unparented/uncontained items.	Guard access to surface->parentItem() and return INT_MAX when the parent item is null. Guard access to surface->container() and return INT_MAX when the container is null. Keep using container->childItems().indexOf(surface) to derive the sort index, asserting the index is non-negative for valid cases.	src/surface/surfacecontainer.cpp

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[sourcery-ai]

Hey - I've left some high level feedback:

• Instead of returning the magic value INT_MAX in multiple places, consider defining a named constant (e.g. kUnreadySurfaceSortOrder) or using std::numeric_limits::max() to improve readability and type safety.
• Given that container->childItems().indexOf(surface) can theoretically return -1 even after your null checks, it may be safer to replace the Q_ASSERT with a conditional that also falls back to the default sort order rather than crashing in release builds.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Instead of returning the magic value INT_MAX in multiple places, consider defining a named constant (e.g. kUnreadySurfaceSortOrder) or using std::numeric_limits<int>::max() to improve readability and type safety.
- Given that container->childItems().indexOf(surface) can theoretically return -1 even after your null checks, it may be safer to replace the Q_ASSERT with a conditional that also falls back to the default sort order rather than crashing in release builds.

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