How do I use older gcc on Ubuntu for one particular build without affecting the system?

Question

On Ubuntu 19.04, I have to build a project that requires an older gcc version that one installed in my system. For certain reasons, I cannot modify makefiles; during the build, gcc command must invoke older gcc, not the default version. How do I achieve that without breaking the default gcc currently installed in the system?

Answer 1

As it turned out, they call gcc through their own internal variable where they also add some flags. After I overrode it from command line:

make CCCMD='gcc-6 ...'

it got fixed.

I just forgot about overriding feature of make.