[PATCH] D117639: [cmake] Avoid warning or extra suffix for CMAKE_INSTALL_LIBDIR

[John Ericson via Phabricator via llvm-commits]

Ericson2314 created this revision.
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Herald added projects: libunwind, Flang.
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We had two related problems with `GNUInstallDirs`:

1. It might default to `lib64`, clashing with LLVM's own `*_LIBDIR_SUFFIX`. I haven't used `CMAKE_INSTALL_LIBDIR` so far for this very reason.

2. Its defaulting logic must go after `project(..)` to work correctly, but `project(..)` is often in a standalone condition making this awkward, since the rest of the condition code may also need GNUInstallDirs.

A simple solution is to just default `CMAKE_INSTALL_LIBDIR` ourselves,
which avoids both issues.

I did this with a little copy-pasted code, but we could factor it out in
`/cmake` instead. I didn't do that yet because it would mean moving the
module path manipulations instead. But if that is desired, I will do it.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D117639

Files:
  flang/CMakeLists.txt
  libcxx/CMakeLists.txt
  libcxxabi/CMakeLists.txt
  libunwind/CMakeLists.txt
  lld/CMakeLists.txt
  lldb/CMakeLists.txt
  llvm/CMakeLists.txt
  polly/CMakeLists.txt
  pstl/CMakeLists.txt

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