[PATCH] D11963: Create a __config_site file to capture configuration decisions.

[Eric Fiselier via cfe-commits]

EricWF added a comment.

I think we can avoid requiring the need to rebuild every time the headers change but it's not the cleanest. We could

1. Have an empty `__config_site` file in `libcxx/include`. This `__config_site` file does not get copied into the build directory.
2. Generate `__config_site.in` into `build-libcxx/include/c++/v1`.
3. Point LIT to `libcxx/include` (not `build-libcxx/include/c++/v1`) and add the flag `-include build-libcxx/include/c++/v1/__config_site` to pick up the generated `__config_site` file.

This way only changes that modify `__config_site` require rebuilding libc++ AND `libcxx/include` can be used as the libc++ include root for most configurations.

Another option would be to have `LIT` itself re-run the build and copy the headers but I don't think this is as good of an option.

Hopefully this all made sense.

@jroelofs What do you think of an approach like this?


http://reviews.llvm.org/D11963