Re: How do linkers deal with C++ duplicate code?

John R Levine <johnl@iecc.com> writes:
> > How do linkers deal with C++ duplicate code?


    Urs Hoelzle <urs@cs.ucsb.edu> wrote:
> The short answer: not very well...


> >-- Templates and extern inline. ...


> Most aren't even as clever as that. For extern inlines, many
> compilers output bodies (and vtables) only when they see the body of
> the first virtual function in the class. Hopefully that function is
> defined in the .cpp file and thus isn't duplicated. (But many C++
> compilers happily duplicate vtables and inlines if the first virtual
> happens to be inline, i.e., has a body in the .h file.)


No, compilers use first non-inline, non-pure virtual function file
to output the vtable. If there is no such function, then it may be
duplicated. So it is a good idea to have at least one non-inline,
non-pure virtual function in a .cc (or, .cpp) file.


    -- Saroj Mahapatra
--

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