can Clang Plugin modify the AST and send it back to the next step of compliation?

Clang Frontend
#1

All the examples of Clang plugin and FrontendActions I’ve read are to get the AST and print some information, I’m curious if I can modify the AST to make some dialect C++ language?

I got some examples I think is easy to do if AST could be modified:

  1. make all subclasses inherit baseclasses’ friend class
  2. make all method virtual (like Java)
#2

Hi,

#3

Hi Miklos, I think applying replacements to original source file is not what I expect, it does not act as a “dialect” to me.

What I want to do gives a feeling of “AST programming” (I just made up this term).

#4

You can have a plugin AST action run before the ‘main’ action (i.e. before compilation) which means that the AST after
the action has run is what is compiled. There’s an example at
https://github.com/llvm/llvm-project/blob/master/clang/examples/AnnotateFunctions/AnnotateFunctions.cpp
which modifies the AST by adding function attributes.

John