Fallback compile flags

[clangd]

Fallback compile flags

[cgurps]

[sam-mccall]

(moving to clang/clangd, this isn't coc-specific)

[sam-mccall]

There is an option in the LSP called initializationOptions.fallbackFlags

Is there? I can't find fallbackFlags in the spec

The idea of supporting some kind of user-specified flags in combination with the compilation database has merit though. (See clangd/clangd#349 which this should also interact with)

[cgurps]

I saw that you could do that here

https://clangd.llvm.org/extensions.html

[sam-mccall]

Oops, sorry, my mistake... indeed this is an extension we have and coc-clangd could have a setting for that.
Let me send it back to the other repo...

[fannheyward]

@cgurps @sam-mccall I've added fallbackFlags according the document, but haven't test it works or not, please give it a review and test #38