Temporarily workaround CMake dependencies bug

[bnbarham]

Workaround a CMake bug in order to make sure that libraries are rebuilt when their dependencies change.

[bnbarham]

swiftlang/swift#62129

@swift-ci please test

[etcwilde]

It's terrible, but I think it works. A few style comments.
Also, can you add reference to rdar://102202478 in a comment? Thanks.

CC @compnerd any thoughts/feedback?

[etcwilde]

The naming here feels a bit weird. I'm not getting that it's linking from the function name, and the PUBLIC seems to come out of nowhere.

[bnbarham]

So I totally agree about the PUBLIC, but I was basically just aiming at making it a 1:1 replacement for target_link_libraries (at least for the case we use it). I don't really mind either way. Do you have a strong opinion here?

How about I rename it to force_target_link_libraries?

[compnerd]

I actually think that this change is far too invasive for what it intends to do. I think that we should be more clever about this workaround. Please rename this function target_link_librares. We can subsequently, at the end of the function passthrough to the underlying implementation of target_link_libraries.

Something like this should do the trick:

function(target_link_libraries target)
  cmake_parse_arguments(TLL_ARGS "" "" "PUBLIC" ${ARGN})

  foreach(dependency ${TLL_PUBLIC})
    ...
  endforeach()

  _target_link_libraries(${target} PUBLIC ${TLL_PUBLIC} ${TLL_ARGN})
endfunction()

This way, in the future, the revert of this will just drop this one function and everything goes back to normal.

[bnbarham]

I had no idea you could do that. I've updated the PR to do this instead, but I'll leave the Swift PR as is - once the function is redefined, it's redefined from that point on (not scoped to a subdirectory). This is fine for swift-syntax, but not for the swift-side change (and that only touches the one file anyway). Thanks for the suggestion @compnerd!

[bnbarham]

swiftlang/swift#62129

@swift-ci please test

[etcwilde]

Yeah, I think the new changes are fine given that the goal is to delete the function.

[compnerd]

I actually think that this change is far too invasive for what it intends to do. I think that we should be more clever about this workaround. Please rename this function target_link_librares. We can subsequently, at the end of the function passthrough to the underlying implementation of target_link_libraries.

Something like this should do the trick:

function(target_link_libraries target)
  cmake_parse_arguments(TLL_ARGS "" "" "PUBLIC" ${ARGN})

  foreach(dependency ${TLL_PUBLIC})
    ...
  endforeach()

  _target_link_libraries(${target} PUBLIC ${TLL_PUBLIC} ${TLL_ARGN})
endfunction()

This way, in the future, the revert of this will just drop this one function and everything goes back to normal.

[bnbarham]

@swift-ci please test