autosave creates new draft on each iteration

[nbachiyski]

Expected behaviour: on each auto-save the current post is saved

Current behaviour for some users:

For some users (I can't reproduce) every time a draft is auto-saved it fails with errors like:

Warning: Invalid argument supplied for foreach() in .../blog/wp-admin/admin-functions.php on line 30 
 
Warning: array_search() [function.array-search]: Wrong datatype for second argument in .../blog/wp-admin/admin-functions.php on line 117 
 
Warning: Illegal string offset: -1197443547 in .../blog/wp-admin/admin-functions.php on line 124

As a result on each auto-save a new draft is created.

Cause: somehow the autosave_draft_ids options is both true and not an array and the default value isn't used:

if ( !$draft_ids = get_user_option( 'autosave_draft_ids' ) )
    $draft_ids = array();

Solution: if $draft_ids isn't tested in boolean, but in array context everything is fine:

if ( !is_array( $draft_ids = get_user_option( 'autosave_draft_ids' ) ) )
    $draft_ids = array();

Patch-attached.

Thanks to Krasimir Dobrev for experiencing and reporting this one.

[Denis-de-Bernardy]

This can happen on some php versions that incorrectly process charsets. It's related to things getting unsuccessfully unserialized, and it has been fixed in r10955