Specify .clang-format and .clang-tidy file location

[xinnjie]

In our team, we have many repo( one server per repo). All repo format is suggested to be same. Instead of put one .clang-format/.clang-tidy in each repo, specify .clang-format and .clang-tidy is more convenient.

[njames93]

Clangd will recursive go up the directory tree looking for those config files, so you could just put them in the root directory above all your repos.

[HighCommander4]

Possibly relevant: https://reviews.llvm.org/D72326

[definelicht]

This would be very useful; .clang-tidy supports the --config-file option, so either an equivalent to this or a way to forward flags to clang-tidy would provide this feature

[njames93]

@sam-mccall If we were to support something like this, How would you want to specify a --config-file option.
I feel like we can rule out a command line flag off the bat, despite it being the easiest implementation.
Putting it in the config sounds kind of ideal, but I feel there's definitely gonna be some hurdles in the implementation of that if we try and match how clang-tidy handles the flag. The main one is that if the config file loaded has InheritParentConfig enabled, we then fallback to loading file relative .clang-tidy config files.
We'd also likely want to use a FileCache for tracking any changes to the file.

[voertler]

What is the status of this? For clang-format the straight forward solution would be to implement the --style option.