[PATCH] D136572: Harmonize cmake_policy() across standalone builds of all projects

Thu Oct 27 05:10:37 PDT 2022

mstorsjo added a comment.

In D136572#3888177 <https://reviews.llvm.org/D136572#3888177>, @mstorsjo wrote:

> This broke builds where clang/lld/lldb are symlinked into `llvm/tools` instead of specified via `LLVM_ENABLE_PROJECTS` - since `${CMAKE_CURRENT_SOURCE_DIR}/../cmake` doesn't find anything in that context.

This aspect, for finding the shared cmake directory, is handled elsewhere by the main LLVM build setting the `LLVM_COMMON_CMAKE_UTILS` variable, and if not found, it's assumed to be in `${CMAKE_CURRENT_SOURCE_DIR}/..`. See e.g. https://github.com/llvm/llvm-project/blob/llvmorg-15.0.0/lld/CMakeLists.txt#L198-L206.

Since this is invoked very early in the per-project cmakefiles, I guess we can't assume to have all those variables set up yet, but e.g. something like this fixes the issue for me:

  diff --git a/lld/CMakeLists.txt b/lld/CMakeLists.txt
  index 964bc3fd8b17..530f52b05bac 100644
  --- a/lld/CMakeLists.txt
  +++ b/lld/CMakeLists.txt
  @@ -1,6 +1,11 @@
   cmake_minimum_required(VERSION 3.13.4)
  -include(${CMAKE_CURRENT_SOURCE_DIR}/../cmake/Modules/CMakePolicy.cmake
  -  NO_POLICY_SCOPE)
  +if(DEFINED LLVM_COMMON_CMAKE_UTILS)
  +  include(${LLVM_COMMON_CMAKE_UTILS}/Modules/CMakePolicy.cmake
  +    NO_POLICY_SCOPE)
  +else()
  +  include(${CMAKE_CURRENT_SOURCE_DIR}/../cmake/Modules/CMakePolicy.cmake
  +    NO_POLICY_SCOPE)
  +endif()

   # If we are not building as a part of LLVM, build LLD as an
   # standalone project, using LLVM as an external library:

(And the same applied for all the other subprojects.) It's admittedly not very pretty though...

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D136572/new/

https://reviews.llvm.org/D136572