Hello, I am new to SU2.

I cloned the git repository and wanted to build it from source (on Debian GNU/Linux).
I noticed that the 'meson.py' script downloads a bunch of external dependencies, including Meson and Ninja (as documented in https://su2code.github.io/docs_v7/Build-SU2-Linux-MacOS/). I wanted to use the system-wide versions of Meson and Ninja that I have installed on my Debian box, hence I had to modify the 'meson.build' file, in order to drop the following lines:

if meson.version() != '0.61.1'
  error('SU2 must be configured with the extended Meson script (./meson.py) in the SU2 root directory.')
endif

And then I had to manually download the relevant external dependencies.
After that, I issued:

$ meson setup -D_configuration-options_ build
$ ninja -C build install

The build was successful, but using system-wide Meson and Ninja could be made easier.

I think that the 'meson.py' script could have an option to avoid downloading Meson and Ninja and to avoid the automatic invocation of the downloaded Meson.

Moreover, the 'meson.build' file should not exit unsuccessfully on the basis of meson.version(), or, at least, should check that meson.version() is equal to or later than a given minimum version.