[PATCH] D137724: [CMake] Warn when the version is older than 3.20.0.

[Mark de Wever via Phabricator via cfe-commits]

Mordante added a comment.

In D137724#3917644 <https://reviews.llvm.org/D137724#3917644>, @MaskRay wrote:

> I think `if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)` checks for standalone builds is not necessary. The check in `llvm/CMakeLists.txt` suffices.
> It's unlikely the users will use different cmake versions to configure llvm and a subproject like clang.

I can remove the others, but we need to keep the one in `runtimes/CMakeLists.txt` too. The runtimes (libc++, libc++abi, and libunwind) can be build without building or configuring LLVM.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D137724/new/

https://reviews.llvm.org/D137724