libstdc++ PATCH to add abi tag to complex::real/imag

[Marc Glisse]

On Sun, 11 Nov 2012, Jason Merrill wrote:

> On 11/11/2012 06:55 AM, Jonathan Wakely wrote:
>> For std::list I assume we want the attribute on the type itself, not
>> just member functions, since its size changes.

When we are changing the whole type, I assume the point of using this
attribute instead of the standard solutions (move it to some other
(inline) namespace, for instance) is the -Wabi-tag warning?

> Yes.  Note that I believe for the list and string changes we want to change 
> the default ABI for C++98 and C++11, not just C++11.  And provide a way for 
> users to select the old ABI if they need to pass string/list objects to and 
> from previously compiled code.

That way is already needed while building libstdc++, and we need to 
compile all files that use string twice during the build, exporting only 
the symbols that contain "cxx11" from one of the builds.

Changing string/list is still an ABI break. Is it for 4.8, or should it 
wait until 4.9?

-- 
Marc Glisse