Feature request: link_hidden argument in library()

[na-trium-144]

When building a shared library which uses external static library (say libA here) internally, I don't want to expose the libA's symbol from my shared library.
One way to achieve this is to set gnu_symbol_visibility: 'inlineshidden' on libA.
But there is also a way to do this without modifying libA: -Wl,--exclude-libs,libA.a in addition to -lA (on Linux) and -Wl,-hidden-lA instead of -lA (on MacOS). This works no matter what the visibility option of libA is.
Unfortunately, doing this in meson will be something like this and a little complicated:

a_proj = subproject(...)
a_dep = a_proj.get_variable('a_dep')
a_lib = a_proj.get_variable('a_lib')
link_depends = []
if host_machine.system() == 'linux'
  a_hidden_dep = declare_dependency(
    dependencies: [a_dep],
    link_args: ['-Wl,--exclude-libs,' + fs.name(a_lib.full_path())],
  )
elif host_machine.system() == 'darwin'
  link_depends += a_lib
  a_hidden_dep = declare_dependency(
    dependencies: [a_dep.partial_dependency(compile_args: true, includes: true)],
    link_args: [
      '-L' + fs.parent(a_lib.full_path()),
      '-Wl,-hidden-l' + a_lib.name(),
    ],
  )
else
  # On Windows just linking normally is ok for me.
  # I don't know about other platform...
  a_hidden_dep = a_dep
endif

# then link it from my library
my_lib = library(
  ...,
  # on MacOS I need to put a_lib into link_depends to avoid linking with -lA,
  # and declare_dependency do not have link_depends
  link_depends: link_depends,
  dependencies: a_hidden_dep,
)
# In reality I want to do this only when my_lib is shared and a_lib is static, and otherwise it should be linked normally.
# so there will be more if statements than this.

So I thought it would be useful if meson implemented an argument like link_hidden: a_lib.

[eli-schwartz]

Hmm. Kind of lame that Apple ld64 doesn't support --exclude-libs. :(

Note that you can also achieve a comparable effect using an ld version script, which is likewise linker-dependent but doesn't need hacking around partial dependencies in order to erase -lA from the link command.