qt5base-lts/mkspecs/features/mac/default_post.prf

load(default_post)
!no_objective_c:CONFIG += objective_c

# Pick a suitable default architecture for qmake-based applications.
# If the Qt package contains one of x86 and x86_64, pick that one. If it
# contains both then use the compiler default. Make a similiar decision for
# PowerPC-based systems. Note that this logic assumes that Qt has been
# configured with an architecture that is usable on the system.
qt:!isEmpty(QT_CONFIG) {
    contains(QMAKE_HOST.arch, ppc)|contains(QMAKE_HOST.arch, "Power Macintosh") {
        !contains(QT_CONFIG, ppc64):contains(QT_CONFIG, ppc):CONFIG += ppc
        contains(QT_CONFIG, ppc64):!contains(QT_CONFIG, ppc):CONFIG += ppc64
    } else {
        !contains(QT_CONFIG, x86_64):contains(QT_CONFIG, x86):CONFIG += x86
        contains(QT_CONFIG, x86_64):!contains(QT_CONFIG, x86):CONFIG += x86_64
    }
}