documentclass{article}

usepackage{scalerel}
usepackage[usestackEOL]{stackengine}

defdashint{,ThisStyle{ensurestackMath{%
            stackinset{c}{.2LMpt}{c}{.5LMpt}{SavedStyle-}{SavedStylephantom{int}}}%
        setbox0=hbox{$SavedStyleint,$}kern-wd0}int}

begin{document}

    $dashint f(t),dt$

end{document}