[Bug c++/84744] cannot use glibc 2.27 with gcc 7.3

["development at faf-ltd dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84744

--- Comment #6 from Peter VARGA <development@faf-ltd.com> ---
(In reply to Marc Glisse from comment #5)
> That's not how you use a different glibc. If you look at the include order
> printed by -v, it has to remain in that order (libstdc++ before glibc, in
> particular), whereas you are adding your glibc in front. Best would be to
> recompile gcc, which has the added advantage that it will be able to take
> advantage of the new features in the new glibc this way.

May be for you all is clear but I am not in the gnu gcc developer team and I am
using only gcc. Therefore I don't really understand what I should do. You all
give just half of some hints and they don't even work.

What should I do different when I recompile gcc?

This works - but why should I do it? Why is g++ using the path /usr/include
BEFORE the others and this is the problem! gcc does NOT keep the include order.

g++ foo.cpp -o foo -nostdinc -I /FaF/include/c++/7.3 -I
/FaF/include/c++/7.3/x86_64-suse-linux/ -I /FaF/glibc/include/ -I
/FaF/lib64/gcc/x86_64-suse-linux/7.3.0/include

In /FaF is my gcc 7.3 and in /FaF/glibc is glibc 2.27