Custom attribute parser with precise error handling

I’m currently working on a custom dialect for MLIR and this dialect requires custom attribute parsing. I already saw [RFC] Exposing MLIR's Tokenizer, Lexer and Parser and accepted the fact that I had to write this on my own. Unfortunately there is a problem with precise error emission:

My custom parser works with SMLocs that then should be converted to a Location but this conversion cannot be done precisely for now. The normal parser uses a SourceMgr that provides functionality to convert pointers to FileLineColLocs but this is hidden away.

The only solutions we (@Kayjukh and I) were able to find, introduce either a coupling of the DialectAsmParser with my custom one or require an error-callback lambda that itself invokes DialectAsmParser::emitError with the SMLocs.

Is there a reason why one is not able to access the SourceMgr or anything else that allows this conversion for custom parsing?