Decompilation output modification in IDA Pro

Question

I am trying to modify cfunc AST from

If (a1 && some_func_ptr) {
  some_func_ptr();
}

To

if (a1) {
  some_func_ptr();
}

But I constantly get INTERR 50683 error. I tried

new_item = idaapi.cexpr_t(item.cif.expr.x)
item.cif.expr.swap(new_item)

Also many other attempts to modify other parts of AST fail in the same way. I suspect that it has something to do with thisown flag, but various changes did nothing.

Answer 1

The 50683 INTERR means address is invalid. There is a check applied by verifier (\IDAFolder\plugins\hexrays_sdk\verifier\cverify.cpp) in cfunc_t::verify_insn function:

case cit_if:
  if ( maturity < CMAT_TRANS1 || maturity >= CMAT_CASTED )
  {
    ea_t jea = i->cif->expr.calc_jmp_cnd_ea();
    if ( jea != BADADDR && i->ea != jea )
      // ctree: mismatch in if-statement and its expression addresses
      CFAIL_QASSERT(50683, i);
  }

There are also many other INTERRs for decompilation in case anyone is looking. So, the correct code in my case had to have something like this:

new_item = idaapi.cexpr_t(item.cif.expr.x)
new_item.ea = item.cif.expr.ea
# or just new_item.ea = idaapi.BADADDR it works too
item.cif.expr.swap(new_item)