Re: [gentoo-dev] Re: stable gcc 5.4.0 ??

[Matthias Maier <tamiko@gentoo.org>]

On Thu, Apr 20, 2017, at 17:17 CDT, "Walter Dnes" <waltdnes@waltdnes.org> wrote:

> ...fun !NOT.  If you're doing a fresh install, ***WITH A GCC5-BUILT
> INSTALL CD AND STAGE 3***, then yes, go for it.  But changing horses in
> mid-stream can be painfull.  Would it hurt to stay with 4.9.4 for the
> time being, assuming that you're not using prebuilt stuff like
> firefox-bin or libreoffice-bin?  What would be the best way to go about
> it?

The technical discussion how to proceed with the new C++ abi happend two
years ago. We decided to do the only sensible thing in switching to the
new C++ abi. (And hopefully only see very minor issues in ABI
incompatibilities later on.)

It unfortunately involves rebuilding parts of your userland.


> A) Would 5.4.0 be slotted separately, and 4.9.4 left as the default?
> B) Add "-D_GLIBCXX_USE_CXX11_ABI=0" to CFLAGS and CXXFLAGS
> C) Mask out ">sys-devel/gcc-4.99"
> D) Allow "--with-default-libstdcxx-abi=gcc4-compatible" via a USE flag?

(A-C) gcc-5.4.0 and gcc-4.9.4 are slotted separately. What is going to
be the default is entirely up to you. If overriding the ABI via (B) is
such a great idea is yours to decide.

(D) will definitely not happen.


> Maybe we should what many enterprises do with Windows; i.e. skip a
> version and go straight to gcc-6.

No. We already stabilized gcc-5. A future stabilization of gcc-6/7 won't
be nearly as painful as this one. There is no reason to skip something.


Best,
Matthias