hdoc uses Clang to parse your C++ code, so anything that Clang compiles should be fine. It's one of the benefits of using a production-quality parser instead of a homemade one like some other tools do.
I actually tried using clang -ast-dump to dump syntax tree of the above code snippet, the result was incomprehensible, because the macro has been expanded by the preprocessor.
The preprocessor will still be run prior to hdoc parsing your code, and the result should be valid assuming the your code is well-formed. C++ AST dumps are generally incomprehensible ;)
Please do try hdoc. The source is now available and there are precompiled binaries available on hdoc.io. It takes about 2 minutes to go from downloading hdoc to seeing your documentation on a website if you use the latter route.
I actually tried using clang -ast-dump to dump syntax tree of the above code snippet, the result was incomprehensible, because the macro has been expanded by the preprocessor.