[CMake] seeking advice for building and testing variants

[Vania Joloboff]

Hi

We have a library that we want to build with N different variants
  in the compile flags for the same source code.
Then in the test phase, I want to build N versions of a benchmark
linked with the N versions of the library, then run the benchmark
and compare.

I can create N subdirectories (one for each variant) in my source dir
with a CMakeLists.txt in each directory that will set  the compile flags
for that variant and build the benchmark for that variant.
  I will get N build directories.

Is this the 'recommended' way of doing in this case,
or there would be a smarter way ?

Vania