Auditor: Avoid setting macOS rpaths for /workspace

[eschnett]

This addresses the first half of #1375, namely pruning /workspace from rpaths.

[giordano]

Please add a test. Which probably means removing broken=Sys.isapple(platform) at

BinaryBuilder.jl/test/auditing.jl

Lines 695 to 696 in 2a5e711

	# Currently we don't filter out absolute rpaths for macOS libraries, no good.
	@test length(libfoo_rpaths) == 1 broken=Sys.isapple(platform)

[giordano]

The fact that tests are passing suggests this isn't doing much.

[giordano]

My understanding of the issue is that the rpath isn't added by the auditor but it's already there at the end of the build, so skipping install_name_tool here is not doing anything at all.

[giordano]

Probably this is also why this wasn't done before: unlike ELF files, we currently don't "update" the rpath list for Mach-O files, only add them if necessary. Which isn't the case here, there's nothing to add in the first place.

[eschnett]

Does the function _rpaths work for macOS? (I don't quite understand your comment – are you saying that we "don't update the rpath list", in the sense that _rpaths doesn't return the rpath list?)

[giordano]

The function you're modifying is adding new directories to rpath. The problem is that ${libdir} is already there. We want to remove that.

[eschnett]

That bit I understood. Let me ask my question differently: How do I get the current list of rpaths in the library? Is there infrastructure for this, or would I be writing a bash script calling install_name_tool?

[giordano]

ObjectFile.jl (which is used in this package extensively) should be able to give you that. I don't remember on top of my head if there's any wrapper function.