Inconsistent doc for return value of wp_generate_attachment_metadata

[Chouby]

The return value of wp_generate_attachment_metadata() is documented as mixed. However, the filter wp_generate_attachment_metadata documents it as array. So I would expect that the return value would be documented as array too.

[SergeyBiryukov]

Thanks for the patch!

It looks like wp_generate_attachment_metadata() can actually return false for an audio or video attachment that doesn't exist in the local filesystem, as previously noted in comment:5:ticket:25649.

Some history here:

• [23766] / #23673
• [25968] / #25649
• [35554] / #34599

Since that was never documented neither in the function nor in the wp_generate_attachment_metadata filter, I think we have two options here:

• Make sure the function indeed always returns an array, as the wp_generate_attachment_metadata filter says.
• Document that it returns false for an audio or video attachment that doesn't exist in the local filesystem.

For consistency with other functions like wp_create_image_subsizes(), I think the first option would be preferable here, see 52603.2.diff​. Looking at the wp_generate_attachment_metadata() instances in core, we don't really expect it to return anything other than an array.

P.S. To complicate things a bit further, wp_read_image_metadata() does return false on failure, same as wp_read_audio_metadata() and wp_read_video_metadata(), but that's probably not super relevant here.