We have "code" to deal with this:
%if %{build_ada}
%if 0%{?gcc_version:%{gcc_version}} > @base_ver@
%define hostsuffix %{binsuffix}
BuildRequires: gcc@base_ver@-ada
BuildRequires: gcc@base_ver@-c++
%else
I guess you failed to %define gcc_version to 10 in the project config?