 Test whether a 'ExtensionFlag' is set
xopt :: ExtensionFlag -> DynFlags -> Bool
xopt f dflags = fromEnum f `IntSet.member` extensionFlags dflags

--
xopt :: ExtensionFlag -> DynFlags -> Bool
xopt f dflags = fromEnum f `IntSet.member` extensionFlags dflags
xopt f dflags = fromEnum f `IntSet.member` extensionFlags dflags