On 2014.03.31 at 14:03 +0100, Nathan Sidwell wrote: > This patch fixes some unexpected behaviour of the Weffc++ and > Wnon-virtual-dtor > flags. The documentation for the latter says it's also enabled by Weffc++, > but > that's untrue. > > The current behaviour of Weffc++ is to warn about any non-virtual dtor in a > non-polymorphic base class (relying on the below described -Wnon-virtual-dtor > case to catch polymorphic classes). Since Edition 3 of Scott Meyer's book, > the > rule has been that it only applies to polymorphic classes. I.e. a > polymorphic > class should not have an accessible non-virtual destructor and all of its > bases > should be likewise. (it's possible earlier editions stated this rule too, but > 3rd ed was what I could find). > > The current behaviour of Wnon-virtual-dtor is to complain about accessible > non-virtual dtors in polymorphic classes. This is what one expects. > > One surprising outcome of the current implementation is that -Weffc++ > -Wno-non-virtual-dtor still complains about the lack of virtual dtors in base > classes. > > This patch: > 1) Clarifies the documentation for -Wnon-virtual-dtor to be for polymorphic > classes and bases of such classes. (i.e. move the 3rd ed Weffc++ behaviour > into > this flag).
I'm not sure that this is a good idea. This changes the existing behavior of -Wnon-virtual-dtor and causes hundreds of new warnings when building LLVM. Wouldn't it make more sense to move the 3rd ed Weffc++ behavior to the -Weffc++ flag alone? -- Markus
