Impossible to solve dependencies loop for gcc-4.8 on precise

Good morning,
I am trying to backport GCC 4.8 to precise as some daily builds that I maintain [1] fails as the compiler miss the
'-std=c++11'
flag for g++.

So, I tried to backport gcc-4.8; I found out some packages are required, so I got:
- eglibc
- gcc-4.8
- gcc-defaults
- gccgo-4.9

I usually try to build them with pbuilder-dist (pbuilder-dist precise build DSC_FILE), but I found out that each of
the above packages requires some binary package generated from another of the source ones.

The verbose error plus comments (preceded by '->' or wrapped as '-> COMMENT <-'):

- eglibc
...
The following packages have unmet dependencies:
Depends: linux-libc-dev (>= 3.2.1) but 3.2.0-94.134 is installed. -> can backport, I think
Depends: linux-libc-dev (>= 3.4) but 3.2.0-94.134 is installed. -> can backport, I think
Depends: libaudit-dev but it is not going to be installed. -> for next errors
Depends: libcap-dev but it is not going to be installed. -> for next errors
Depends: libselinux-dev which is a virtual package. -> can backport, I think
Depends: g++-4.8 which is a virtual package. -> is in the packages to backport above! (gcc-4.8 + gcc-defaults) <-
Depends: g++-4.8-multilib which is a virtual package. -> kinda the same of previous line <-
Unable to resolve dependencies! Giving up...
...

- gcc-4.8
...
Depends: libc6-dev-x32 which is a virtual package. -> is in the packages to backport above! (eglibc) <-
Depends: libx32gcc1 which is a virtual package. -> is in the packages to backport above! (gccgo-4.9) <-
-> all the packages below can be installed but they won't as previous dependencies are missing... <-
Depends: libc6-dbg but it is not going to be installed.
Depends: m4 but it is not going to be installed.
Depends: libtool but it is not going to be installed.
...

- gcc-defaults
...
Depends: gcc-4.8-base (>= 4.8.1-6~) which is a virtual package. -> is in the packages to backport above! (gcc-4.8) <-
-> all the packages below can be installed but they won't as previous dependencies are missing... <-
Depends: lsb-release but it is not going to be installed.
Depends: ca-certificates but it is not going to be installed.
...

- gccgo-4.9
...
Depends: libc6-dev-x32 which is a virtual package. -> is in the packages to backport above! (eglibc) <-
Depends: libx32gcc1 which is a virtual package. -> is in the packages to backport above! (gccgo-4.9), also is the same package! <-
-> all the packages below can be installed but they won't as previous dependencies are missing... <-
Depends: libc6-dbg but it is not going to be installed.
Depends: m4 but it is not going to be installed.
Depends: libtool but it is not going to be installed.
...

Some ideas to escape this hell?