:-1: error: error: unrecognized command-line option '-mylibrary'

[ajayvardhan]

[SGaist]

Hi and welcome to devnet,

You might want to give a bit more details and explanation about your issue rather than just posting a picture.

That said, based on that image, the issue comes from your calculator project.

[ChrisW67]

Further to @SGaist's observation, I would guess that the calculator PRO file has an incorrect LIBS variable, e.g..

LIBS += ... -mylibrary

rather than

LIBS += ... -lmylibrary