[llvm-dev] Issues with the precompiled LLVM 12 for macOS

[Alex Denisov via llvm-dev]

Hey folks,

I just wanted to send you a heads up that there is an issue with the precompiled LLVM package for macOS.
The LLVMConfig.cmake has a very specific path hardcoded in it:

    set_target_properties(LLVMSupport PROPERTIES
      INTERFACE_LINK_LIBRARIES "m;ZLIB::ZLIB;/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk/usr/lib/libcurses.tbd;LLVMDemangle"
    )

Any build that depends on LLVMSupport fails unless there is this very specific macOS SDK present.

The workaround is rather straightforward:

    find_package(LLVM REQUIRED CONFIG)

    if (APPLE)
      if (LLVM_VERSION_MAJOR EQUAL 12)
        set_target_properties(LLVMSupport PROPERTIES
          INTERFACE_LINK_LIBRARIES "z;curses;m;LLVMDemangle")
      endif()
    endif()

It never happened before at least since the version 3.9, so I guess an automated check might be an overkill.
But I'm curious how can we prevent this from happening again?

Cheers,
Alex.