I am trying to write a silly tool using Rust that transforms C code like this

int sys_close(int fd) {
  file_t *f = proc_getfile(proc_curr(), fd);
  if (!f){
    return -1;
  }else{
    fclose(f);
    proc_curr()->files[fd] = NULL;
    return 0;
  }
}

to this

int sys_close(int fd) {
  return ({
    file_t *f = proc_getfile(proc_curr(), fd);
    !f ? -1 : (fclose(f), proc_curr()->files[fd] = NULL, 0);
  });
}

To make this transformation, I want to first generate an AST from C source code, then reorder elements in the AST, and finally print transformed code by visiting the tree.

I do not want to write a parser myself, so I am looking for a Rust crate to generate the AST for me. Becasue this tool only cares about tranformation of code in a small range of code, so it’s better that the crate does not perform semantic checks and only focus on generating an AST.

I tried lang-c, but it seemed to performed some kind of type check, because undeclared types such as uint32_t is regarded as a SyntaxError. Also lang-c uses either clang or gcc as its frontend so include file will be checked. I want a library that does not perform any kind of check or try to read include files, only to parse input source code and generates an AST. I want to know whether there is a crate matches my need.

Thanks in advance.