On 15 April 2012 13:53, Mathias Gaunard <mathias.gaunard@ens-lyon.org> wrote:
Calling delete on a pointer to a polymorphic type with a non-virtual destructor might be a bug. It would be a bad idea for shared_ptr to disable this warning for any other type than error_info.
But shared_ptr is explicitly written to deal with this case so the warning is almost always incorrect (remember that if you delete the object by some other means, the warning will appear for the other deletion). You can see this tested in shared_ptr_test. Look at the contents of n_spt_abstract (in a couple of places). Note also that gcc's std::shared_ptr does not warn for this use case.
The simplest solution is to make the destructor of error_info virtual, since it doesn't add any significant overhead, especially compared to how bloated Boost.Exception is as a whole...
This isn't just about Boost.Exception. I'm not arguing against it making its destructor virtual.
It would also have the advantage of not relying on fragile compiler-specific warning suppression mechanisms.
Since this warning was added in 4.7, the warning mechanism introduced in 4.6 can be used. It isn't fragile.
As a rule, rewriting the code so that the warning doesn't happen is much more valuable than disabling the warning.
Sometimes that's that case, but sometimes the opposite is true. Rewriting code can cause unnecessary complexity and introduce bugs. Especially when you consider the multitude of warnings we have to deal with.