F21 system GCC changed to 4.9.0 prerelease

[Jakub Jelinek]

On Fri, Apr 11, 2014 at 09:15:35AM -0400, Josh Boyer wrote:
> Seems they were enabled for RPM in rawhide and now a mock chroot fails
> to init because RPM explodes.  This is from a noarch (which is run on
> an ARM builder) build from a scratch build.

For -fsanitize=address (and -fsanitize=thread), it is usually needed that
if some shared library is instrumented with that, the binary linking against
that or especially dlopening such shared libraries is also instrumented (the
same).  So, I'd strongly recommend against enabling -fsanitize=address for
building of shared libraries some other packages might need to dlopen, do it
only in your own scratch builds, not in anything you install into rawhide.
The thing with these two is that libasan.so (or libtsan.so) needs to be
initialized very early, before other shared libraries that might be
instrumented run their constructors.
Also, -fsanitize=address has been tested much more on x86_64/i686 than on
other architectures.
And, -fsanitize=address is incompatible with -fsanitize=thread, you can only
have one kind of instrumentation from these in the whole process.

-fsanitize=undefined instrumented shared libraries can be dlopened just
fine, but don't forget to disable the instrumentations say after beta.

	Jakub