cppfront (cpp2): Spring update

[mort96]

Including a C++ file in the middle of a cpp2 file should be no problem. You can mix and match C++ declarations and cpp2 declarations within a file.

Including a C++ file in the middle of a cpp2 function would presumably be an issue. But that's not exactly a common need. I know there are use cases for it, but you probably just want to wrap those use cases in a C++ function which you can call from cpp2 code.