Add option for XML_UNICODE_WCHAR_T in CMakeLists.txt

[frast]

Would it be possible to add an option in CMakeLists.txt to switch XML_UNICODE_WCHAR_T ON? I want this to add a feature to the portfile in vcpkg, which compiles expat with this option. Is this a good idea or are there other ways to do this? I do not know how to work with cmake, so I am not able to come up with a patch for this. Any help would be appreciated.

[hartwork]

Sounds like a good idea, yes.

There are four related options that are included with CMakeLists.txt as of now: XML_DTD, XML_NS and XML_CONTEXT_BYTES (that affect rendering of expat_config.h.cmake to expat_config.h) and XML_DEV_URANDOM (that adds -DXML_DEV_URANDOM to preprocessor flags on non-Windows platforms, directly).

The way that XML_DEV_URANDOM works with CMake right now seems inconsistent for no good reason. So I'd propose to first make XML_DEV_URANDOM work like XML_DTD and friends (with an entry in expat_config.h.cmake and using set, then add two new options just like them for XML_UNICODE and XML_UNICODE_WCHAR_T.

Are you sure you want to pass on this chance to get a little closer to CMake, getting review and contributing to Expat? If things get merged your name will be in the change log as well :)

[frast]

I created a pull request.