[clang] [clang-tools-extra] [llvm] [clangd] introduce doxygen parser (PR #150790)

[via cfe-commits]

tcottin wrote:

The idea was to be able to parse the doxygen comments directly from strings without the need for the `ASTContext`.
This allows to keep the clangd index as is and create the hover/code completion content only when requested using the stored documentation strings from the index.

I am not very familiar with clang-doc, but looking through the code a bit, it doesn't look like this would be possible with clang-doc.

Also it looks like clang-doc is designed to write out all documentation for all the code.
For the clangd use case, we only need the documentation for single code entities.


https://github.com/llvm/llvm-project/pull/150790