@simonpj points out that ghc/ghc> isn't shown in the search interface's project filter field.
https://gitlab.haskell.org/search?utf8=%E2%9C%93&snippets=&scope=&search=capturetopconstraints&project_id=55
changed the description
assigned to @bgamari
changed title from GHC project not shown in project field field to GHC project not shown in search interface's project filter field