[PATCH] D49672: [CMake] Honor LLVM_EXTERNAL_<proj>_SOURCE_DIR

[Chris Bieneman via Phabricator via llvm-commits]

beanz added a comment.

Yes, this is the preferred way to do this. No, we don’t need a big comment about it. The solution I described is how you define command-line configurable options in CMake that are not Boolean (for Boolean options CMake has the `option` function which is really just a wrapper around this pattern).

If you look in AddLLVM.cmake you can see that this variable was originally intended to be a cache-exposed variable, and it was a bug adding this code that it didn’t preserve cache behavior. See:
https://github.com/llvm-mirror/llvm/blob/master/cmake/modules/AddLLVM.cmake#L992

There is probably a good cleanup opportunity for this to reduce down to one site for the set, but you don’t need that to resolve your current bug.


Repository:
  rL LLVM

https://reviews.llvm.org/D49672