Extra fields in C++ AST classes

[Léo Sarrazin]

Is there a standard way to add fields to AST classes in C++? for example a reference resolution or the inferred type of an expression. I did not found any article or paper about that on the net.

[Andreas Abel]

No, there is no such mechanism in BNFC. I used a workaround where I
patch the BNFC-generated parent classes automatically (in the Makefile)
after they have been generated. By "parent class" I mean for instance
"Exp", when the child classes are the particular forms of an expression,
like EInt, and EAdd, link in the LBNF grammar:

EInt. Exp ::= Integer;
EAdd. Exp ::= Exp "+" Exp;

[Léo Sarrazin]

I try to know the best way to do things. Actually i use 2 visitors, one for pre-referencing classes and namespaces in the language, and another visitor to type check expressions or check other kind of language rules. The first one take a pointer to the second to fill intern states that i need for the second pass, i dont know if this is the best way to do it.
If you have any other advice for the backend in C++ you welcome, thank you for the tip!

[Andreas Abel]

I am afraid I do not have enough insight in your problem to give
specific advice.

You might consider to use the BNFC-generated AST only for parsing, and
roll your own syntax trees for later passes.

[Léo Sarrazin]

Reconstructing the entire ast would be overkill i think, i will consider your first advice and try to do something. Anyway if someone have documents or other references about this topic im more than interrested.