Your new compiler will be at ~/gcc10/bin/gcc

gistfile1.txt

sudo apt install -y curl build-essential libgmp-dev libmpfr-dev libmpc-dev
mkdir /tmp/$$ && cd /tmp/$$
curl -s https://ftp.gnu.org/gnu/gcc/gcc-10.3.0/gcc-10.3.0.tar.xz | tar xJ
mkdir build && cd build
../gcc-10.3.0/configure --prefix=$HOME/gcc10 \
                        --disable-dependency-tracking \
                        --disable-nls \
                        --disable-multilib \
                        --enable-default-pie \
                        --enable-languages=c,c++
make -j$(nproc)
make install

https://www.reddit.com/r/debian/comments/mmure2/upgrading_the_gcc_gnu_compiler_in_buster/

https://gcc.gnu.org/wiki/FAQ#configure

GCC tends to have problems when configured in the same directory as the GCC source code, or in any subdirectory therein

So put your objdir up a level:

$ git clone ... gcc
$ mkdir objdir
$ cd objdir
$ ../gcc/configure ...

If you're just building a native compiler, you don't need --host. It will figure that out on its own. Just pick an install prefix, --prefix=, which is where your compiler will go when you make install. You don't need it installed in the system. Just put it somewhere your user has write permissions, then add that to your PATH.

https://www.reddit.com/r/gcc/comments/1aer9tx/recommendations_for_building_gcc_on_linux_box/

https://gcc.gnu.org/wiki/InstallingGCC