I see it working this way at least back to 1.16; definitely seems wrong though.

(In reply to comment #0)

Using the manualthumb feature (thumb= inside a imagelink) looks broken.
(Search for 'manualthumb' in Linker.php)

Broken because:

• The image is linking to the file under thumb=. In my opinion this feature

makes no sense with this link, when only the magnify link links to the
original
file

This should be fixed now https://gerrit.wikimedia.org/r/#/c/51075/

• It is not possible to set a size for the image. It is always loaded in full

size

By original design, though....not great. ;)

• nice to have: the thumb= param should ignore a File namespace
• the used image is not registered in the iamgelinks table, makes it hard to

find all usages

Ugh :P

Keep and fix or drop that feature?

I'd love to kill it, probably most cases can be replaced with either default thumbnailing or use of link= to point at the alternate full-size image.

But no need to kill it immediately.

Provisionally closing this for the main bug.

I suggest opening another bug for "the used image is not registered in the imagelinks table", since I ran into this issue yesterday while trying to find all the uses of thumb= to figure out if the proposed srcset change would break them.

Setting a size for the image is part of the original design; a separate feature request bug might be worthwhile there if you really want to see that done.