System - Hirsute 21.04 with GCC 10.3.0.
Also, GCC 11.1.0 was installed:
$ g++-11 --version
g++-11 (Ubuntu 11.1.0-1ubuntu1~21.04) 11.1.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Running make -C depends qt_configured CC=gcc-11 CXX=g++-11, I got:
...
Configure summary:
Building on: linux-g++ (x86_64, CPU features: mmx sse sse2)
Building for: linux-g++-64 (x86_64, CPU features: mmx sse sse2)
Target compiler: gcc 10.3.0
...