-> FilePath -- Importing module: used only for error msg
-> Module -- Imported module
-> IsBootInterface -- Source import
-> Bool -- Record dependency on package modules
-> IO (Maybe FilePath) -- Interface file file
-> FilePath -- Importing module: used only for error msg
-> Module -- Imported module
-> IsBootInterface -- Source import
-> Bool -- Record dependency on package modules
-> IO (Maybe FilePath) -- Interface file file