How to configure buildroot to generate toolchain with C++ support?

The toolchain generated by buildroot on buildroot/output/host/build has support for C but not C++. I intend to compile C++ programs to run under Linux in a CVA6 system (Cheshire) and I would like to use the buildroot toolchain.

I see on sw/deps/cva6-sdk/buildroot/package/gcc/gcc-initial/gcc-initial.mk that the BR2_INSTALL_LIBSTDCPP should add c++ to the --enable-languages option. So I have added "BR2_INSTALL_LIBSTDCPP=y" and "BR2_TOOLCHAIN_BUILDROOT_CXX=y" to buildroot64_defconfig, and ran make clean-all, make gcc, yet a C++ toolchain is not generated.

Any ideas on how to proceed?

Thank you.