Feature summary
enable a method in WikibaseCirrusSearch to search

haswbstatement:P="some value"

according to https://www.mediawiki.org/wiki/Topic:Y0xpx24kqflouykq it's not possible now.

Use case(s)
sdc for commons users' own works is done this way: P170=some value with qualifier P4174.

which means

haswbstatement:P170="some value"[P4174=Username]

should get all the files by a user? unless there's another way to do it with WikibaseCirrusSearch, the proposal enables this search.