The closure of ‘qtbase’ is unreasonable large, and this is in part because it retains a reference to GCC:
--8<---------------cut here---------------start------------->8--- $ guix graph -t references --path qtbase /gnu/store/gqld7hz5vm4g904g7nc77z7wzvdrrwyb-zlib-1.2.13 /gnu/store/0zqk6bmgvwxh1kx963hhknwnqh3h0iik-qtbase-6.3.2 /gnu/store/5lqhcv91ijy82p92ac6g5xw48l0lwwz4-gcc-11.3.0 /gnu/store/gqld7hz5vm4g904g7nc77z7wzvdrrwyb-zlib-1.2.13 $ guix build -e '(@@ (gnu packages commencement) gcc-final)' /gnu/store/930nwsiysdvy2x5zv1sf6v7ym75z8ayk-gcc-11.3.0-lib /gnu/store/5lqhcv91ijy82p92ac6g5xw48l0lwwz4-gcc-11.3.0 $ guix size qtbase | tail -1 total: 1204.7 MiB $ guix describe Generation 265 Jun 04 2023 23:48:31 (current) guix eed55a6 repository URL: https://git.savannah.gnu.org/git/guix.git branch: master commit: eed55a6544d5bda2245ec853e5fa4b28e1865bea --8<---------------cut here---------------end--------------->8--- This comes from a CMake file: --8<---------------cut here---------------start------------->8--- $ grep -r 5lqhcv91ijy82p92ac6g5xw48l0lwwz4 /gnu/store/0zqk6bmgvwxh1kx963hhknwnqh3h0iik-qtbase-6.3.2 /gnu/store/0zqk6bmgvwxh1kx963hhknwnqh3h0iik-qtbase-6.3.2/lib/cmake/Qt6/qt.toolchain.cmake: set(__qt_initial_c_compiler "/gnu/store/5lqhcv91ijy82p92ac6g5xw48l0lwwz4-gcc-11.3.0/bin/gcc") /gnu/store/0zqk6bmgvwxh1kx963hhknwnqh3h0iik-qtbase-6.3.2/lib/cmake/Qt6/qt.toolchain.cmake: set(__qt_initial_cxx_compiler "/gnu/store/5lqhcv91ijy82p92ac6g5xw48l0lwwz4-gcc-11.3.0/bin/c++") --8<---------------cut here---------------end--------------->8--- We should remove this reference. Ludo’.