It seems to be related to the mingw-w64 tool chain. If I set the compiler to the 'mingw.org' tool chain, everything works as expected. Is there a way to check to see what the parser doesn't like about the mingw-w64 headers?
Incidentally, there seems to be a bug in that the default compiler headers are parsed irregardless of what the compiler is set to in the project.
The simple logic when CC get all the compiler headers directory is:
1. CC will run a dummy preprocessor command "cpp -v -E -x c++ nul"
2. Then CC will read the output of this command and parse (If I remember correct, it use regex match) this file and correct all the directories as it's search path.
To your problem, it seems: the directories were not correctly parsed by CC, so you need to add them manually.
I don't have a Win64 system, But I think it is easy to fix.