Re: RFC: PATCH to add abi_tag attribute

[Florian Weimer <fweimer at redhat dot com>]

On 11/06/2012 05:03 AM, Jason Merrill wrote:
> +The @code{abi_tag} attribute can be applied to a function or class
> +declaration.  It modifies the mangled name of the function or class to
> +incorporate the tag name, in order to distinguish the function or
> +class from an earlier version with a different ABI; perhaps the class
> +has changed size, or the function has a different return type that is
> +not encoded in the mangled name.

> +A redeclaration of a function or class must not add new ABI tags,
> +since doing so would change the mangled name.

I'm not sure if this sufficiently far-reaching.  It seems that this 
doesn't allow me to implement a virtual function which takes a 
std::string parameter in new-ABI-mode when the base class is also used 
in old-ABI-mode.

I really see no way to deal with this with either old-ABI-by-default 
(without explicit annotations), annotations on legacy headers, or some 
form of automated cross-translation-unit feedback.

--
Florian Weimer / Red Hat Product Security Team