Re: Debugging missing vtables

[Ian Lance Taylor <ian at airs dot com>]

Florian Weimer <fw@deneb.enyo.de> writes:

> On some large application (not written by me), GCC 4.0 does not emit
> some vtables, and link errors are the result.
> 
> If I understand things correctly, a certain member is deemed the
> controlling member, and the vtable is emitted in the translation unit
> which contains this member.
> 
> Is there a way to cause GCC to print this member?  I think this would
> help me to debug this issue.  (It's probably a bug in the application,
> but I'm not completely sure.)

>From the documentation:

    C++ virtual functions are implemented in most compilers using a lookup
    table, known as a vtable.  The vtable contains pointers to the virtual
    functions provided by a class, and each object of the class contains a
    pointer to its vtable (or vtables, in some multiple-inheritance
    situations).  If the class declares any non-inline, non-pure virtual
    functions, the first one is chosen as the ``key method'' for the class,
    and the vtable is only emitted in the translation unit where the key
    method is defined.

I don't know of any way to print the member.

Ian