[PATCH] Document new LLVM CMake interface and emit warning when using llvm_map_components_to_libraries

[Brad King]

On 07/28/2014 09:25 AM, Dan Liew wrote:
> Although it is true that this documentation is for projects that
> "piggy-back" off the LLVM Autoconf/Makefile build process, it is also
> for projects that build outside of the LLVM tree (e.g. KLEE) against
> LLVM libraries (but still piggy-backing off LLVM's Makefiles) which
> the new infrastructure can do (and more because it can build against
> an installed LLVM as well).

Users likely already refer to the current document for the old CMake
usage instructions.  That location should be updated as your patch
does now.  If another document could benefit from similar information
then you could add it there too or link them.

> An alternative I guess would be to fix up LLD and Clang so that they
> use the new LLVM Exported targets when built outside the LLVM build
> tree (currently they invoke the llvm-config executable to get the
> information they need) and once that works properly document this
> process in Projects.rst. If you think that's sensible then a
> discussion about this should probably go to llvm-dev.

Yes, that is sensible.  That is why I added those LLVM_BUILD_* values
to the LLVMConfig in the build tree in the first place.

Thanks,
-Brad