Re: Is gcc warning about non-virtual destructor useless?
Tony Delroy <tony_in_da_uk@yahoo.co.uk> writes:
On Aug 14, 3:41 am, Thomas Maeder <mae...@glue.ch> wrote:
Frank Birbacher <bloodymir.c...@gmx.net> writes:
The warning reads "warning: 'struct Visitor' has virtual functions but
non-virtual destructor". It is warning not to try polymorphic deletion
through a base pointer.
My opinion is that the compiler should produce a diagnostic only when
your code actually evaluates a delete expression where the argument is
of type Visitor *.
And that the protected-ness of the destructor is irrelevant to this
question. Even if it were private could you evaluate such a delete
expression.
Destructors aren't only called by delete. Local variables have their
destructors called too.
True, but not relevant. The virtualness of the destructor of a class
only matters if it is a base class and an object of a derived class
iss deleted through a pointer to the base class.
Your approach is particularly flawed in enterprise library code.
Library developers might not code a problematic delete, but that
doesn't mean the issue won't bite their clients.
Nothing forbids library developers to do design, such as determining
the right way to destruct objects of a class they write, nor to
document that way and to test whether it works.
Waiting for a client to try to use broken code in a way that causes
undefined behaviour (and not the "technically this is undefined but
we all know it's ok (at least on any semi-sane architecture) type of
undefined behaviour) is a really bad idea.
True. I haven't advocated that.
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