macOS: libjulia.dylib version changed from 1.0.0 to 0.0.0, breaking CxxWrap and all (?) JLLs built against libjulia

[fingolfin]

With current master builds, I cannot use CxxWrap on macOS, I get this errror:

julia> using CxxWrap
[ Info: Precompiling CxxWrap [1f15a43c-97ca-5a2a-ae31-89f07a497df4]
ERROR: LoadError: InitError: could not load library "/Users/mhorn/.julia/artifacts/1417b691b9d1117225089c656ede8940fbf2eba8/lib/libcxxwrap_julia.0.8.2.dylib"
dlopen(/Users/mhorn/.julia/artifacts/1417b691b9d1117225089c656ede8940fbf2eba8/lib/libcxxwrap_julia.0.8.2.dylib, 9): Library not loaded: @rpath/libjulia.dylib
  Referenced from: /Users/mhorn/.julia/artifacts/1417b691b9d1117225089c656ede8940fbf2eba8/lib/libcxxwrap_julia.0.8.2.dylib
  Reason: Incompatible library version: libcxxwrap_julia.0.8.2.dylib requires version 1.0.0 or later, but libjulia.dylib provides version 0.0.0
Stacktrace:
  [1] dlopen(s::String, flags::UInt32; throw_error::Bool)
    @ Base.Libc.Libdl ./libdl.jl:114
  [2] dlopen(s::String, flags::UInt32)
    @ Base.Libc.Libdl ./libdl.jl:114
  [3] macro expansion
    @ ~/.julia/packages/JLLWrappers/KuIwt/src/products/library_generators.jl:61 [inlined]
  [4] __init__()
    @ libcxxwrap_julia_jll ~/.julia/packages/libcxxwrap_julia_jll/KSGmQ/src/wrappers/x86_64-apple-darwin.jl:9
  [5] _include_from_serialized(path::String, depmods::Vector{Any})
    @ Base ./loading.jl:669
  [6] _require_search_from_serialized(pkg::Base.PkgId, sourcepath::String)
    @ Base ./loading.jl:755
  [7] _require(pkg::Base.PkgId)
    @ Base ./loading.jl:993
  [8] require(uuidkey::Base.PkgId)
    @ Base ./loading.jl:909
  [9] require(into::Module, mod::Symbol)
    @ Base ./loading.jl:896
 [10] include
    @ ./Base.jl:386 [inlined]
 [11] include_package_for_output(pkg::Base.PkgId, input::String, depot_path::Vector{String}, dl_load_path::Vector{String}, load_path::Vector{String}, concrete_deps::Vector{Pair{Base.PkgId, UInt64}}, source::Nothing)
    @ Base ./loading.jl:1208
 [12] top-level scope
    @ none:1
 [13] eval
    @ ./boot.jl:360 [inlined]
 [14] eval(x::Expr)
    @ Base.MainInclude ./client.jl:446
 [15] top-level scope
    @ none:1
during initialization of module libcxxwrap_julia_jll
in expression starting at /Users/mhorn/.julia/packages/CxxWrap/ZOkSN/src/CxxWrap.jl:1
...

Indeed, in my latest master build from an hour or so ago, I see this:

$ otool -L usr/lib/libjulia.dylib
usr/lib/libjulia.dylib:
	@rpath/libjulia.dylib (compatibility version 0.0.0, current version 0.0.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.250.1)

While with a build of the release-1.5 branch, I see this:

$ otool -L usr/lib/libjulia.dylib
usr/lib/libjulia.dylib:
	@rpath/libjulia.dylib (compatibility version 1.0.0, current version 1.5.4)
	@rpath/libosxunwind.dylib (compatibility version 0.0.0, current version 0.0.0)
	@rpath/libLLVM.dylib (compatibility version 1.0.0, current version 9.0.1)
	/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1575.17.0)
	/usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 400.9.4)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.250.1)

The same in the latest nightly build:

$ otool -L /Volumes/Julia-1.6.0-DEV-624e734698/Julia-1.6.app/Contents/Resources/julia/lib/libjulia.dylib
/Volumes/Julia-1.6.0-DEV-624e734698/Julia-1.6.app/Contents/Resources/julia/lib/libjulia.dylib:
	@rpath/libjulia.dylib (compatibility version 0.0.0, current version 0.0.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1281.100.1)

So the compatibility and current version are not set anymore for these builds.

[fingolfin]

This regression was introduced in commit 2e3364e from PR #38160 by @staticfloat . It is IMHO a blocker for 1.6 and a fix ought to be backported to the release-1.6 branch.