Allow multiple config files

[fetzerch]

Extend '--config-file' command line option to support multiple config files. The configuration parameters get merged recursively.

This is useful to ship a definition of 'additional_commands' with a library of CMake modules while still allowing the user to provide his own project specific config file.

[cheshirekow]

Hi! Thanks for the contribution. I think I agree that there's a need for multiple config loads so that you can get libraries of command specifications. A quick glance of the code looks good. I will follow up soon.

[cheshirekow]

Just an FYI: I'm going to follow this up with some kind of include config file option. I think that rather than specifying multiple config files on the command line, it would be nicer for one config file to be able to refer to another.

[JohelEGP]

I'm working on #201 and will soon make a WIP PR for it at https://github.com/TheLartians/Format.cmake/. Note that the configuration parameters are not being merged recursively. So only the last config with additional_commands is taken into account and previous ones discarded.

[cheshirekow]

Hi @JohelEGP, I think the dictionary merge implementation should be merging the additional commands. If not, that sounds like a bug.

[JohelEGP]

Then it seems like there's a bug. Should I open a new issue for that?

[cheshirekow]

Yes please!