# If HAVE_RULES=yes is passed to qmake, use PCRE and enable rules contains(HAVE_RULES, [yY][eE][sS]) { CONFIG += use_pcre_rules } use_pcre_rules { DEFINES += HAVE_RULES LIBS += -L../externals -lpcre INCLUDEPATH += ../externals message("Rules enabled - to disable them and remove the dependency on PCRE, pass HAVE_RULES=no to qmake.") } else { message("Rules disabled - to enable them, make PCRE available and pass HAVE_RULES=yes to qmake.") }