# Layout Code Reviewer Checklist

## General

- Follow the general [reviewer checklist](https://firefox-source-docs.mozilla.org/contributing/reviewer_checklist.html).

## Security issues

- **Watch for raw pointers that may have their data deleted out from under
  them**. Examples:

  - If you ever have a raw pointer to a dynamically allocated object, it's good
    to scrutinize whether the object might be destroyed before the last
    possible use of the raw pointer. For example: if you have a local variable
    that points to an object that's owned by a {searchfox}`frame's property table <layout/base/FrameProperties.h>`,
    then consider whether the frame might remove/replace the property-table
    entry (or whether the frame itself might be destroyed) inside any of the
    function calls that happen while the local pointer is in scope.
  - Be aware that layout flushes
    (e.g. `doc->FlushPendingNotifications(FlushType::Layout)`) can
    synchronously cause the frame tree (and even the document!) to be
    destroyed. Specifically: a layout flush can synchronously cause resize
    events to fire; and the event-listeners for those events can run arbitrary
    script, which could e.g. remove the iframe element that's hosting the
    document whose layout we're in the midst of flushing; and that can cause
    that document to be immediately destroyed, if there aren't any other strong
    references keeping it alive.