Compilation error on commented-out code

Hello and good day.

I have encountered an interesting compilation error that appears/disappears depending on the existence of a statement.

[Background]
I am still exploring around clang and currently trying the following guide:
http://clang.llvm.org/docs/RAVFrontendAction.html
At first I was having a hard time reconciling the compilation process as my thought process was:

  1. is cmake needed since CmakeLists.txt? isn’t this usually for win builds?
  2. oh well, why not try using cmake? (note: I don’t have prior experience with cmake)
    after a few hours …
  3. hmmm, the cmake operation created some directories and compiling took a long time and the find-class-decls executable was nowhere to be found.
  4. no choice, ill just try to copy directly the Makefile of other tools. (ignoring the CMakeLists for now)
    After some time, compilation was ok and was now exploring around on how to work with source codes being passed.
    This exploration covered around CommonOptionsParser and ClangTool.
    I added some source code, and for reference, the main() now looks like this: