setup emacs foc C++ with ccls and lsp

So ccls is a lsp wrapper for clang it works as a backend that indexes source code and gives emacs index information for better navigation and refactoring of c++

I have had a few issues with the tool’s setup in emacs enviroment. and found the following things that may need extra attention

.ccls file, this file basically does two things

tell ccls how to index the file using clang
before index the file tell clang how to compile and interpret the code as there is a mixture of options for ccls and arguments for clang, need to pay extra attention

usually lines in .ccls file start with % is for ccls, and lines start with - is for clang

c and c++ code/mode, it is better to set only for c++ as c++ is a super set of c
company completion of header files should work without input the surrounds of header file e.g, "" or <>
some times ccls complains it cannot find header file, so you may include the root path of the header files by adding -IincludePath to .ccls files
for large projects using compile_commands.json to guide cclsindexing. you may of course set partial folder for index by setting the black list ow white list if indexing is way too slow
setting key bindings in emacs, the priority is: local-settings > global-settings > define-key