[all-commits] [llvm/llvm-project] 8d2676: [CMake] Use -isystem flag to access libc++ headers

[Petr Hosek via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 8d26760a95bae34aa5c1161a1c2ab8c1cdaa10a1
      https://github.com/llvm/llvm-project/commit/8d26760a95bae34aa5c1161a1c2ab8c1cdaa10a1
  Author: Petr Hosek <phosek at google.com>
  Date:   2020-10-01 (Thu, 01 Oct 2020)

  Changed paths:
    M libcxx/include/CMakeLists.txt
    M llvm/runtimes/CMakeLists.txt

  Log Message:
  -----------
  [CMake] Use -isystem flag to access libc++ headers

This is a partial revert of D62155. Rather than copying libc++ headers
into the build directory to be later overwritten by the final headers,
use -isystem flag to access libc++ headers during CMake checks. This
should address the occasional flake we've seen, especially on Windows
builders where CMake fails to overwrite __config with the final version.

Differential Revision: https://reviews.llvm.org/D88454