[dbus] Cleanup, fix pkgconfig for osx

[dg0yt]

• What does your PR fix?

  Fixes -lLIBRT-NOTFOUND in pc files on osx. Discovered by [vcpkg_fixup_pkgconfig] Check for more problems, add unit test #23898.

• Which triplets are supported/not supported? Have you updated the CI baseline?

  no changes

• Does your PR follow the maintainer guide?

  yes

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

  yes

@Neumann-A Should we add an x11 feature, or disable x11 for osx?

[dg0yt]

This port needs three dirs in share:

• dbus aka ${PORT}
• dbus1 for session.conf
• DBus-1 for CMake config

[Neumann-A]

@Neumann-A Should we add an x11 feature, or disable x11 for osx?

I don't have any feelings if it should be a feature for osx. If people could want it, make it a feature, otherwise disable it for osx.

[autoantwort]

I think you can disable x11 on osx. It is not really a thing on macos and only works if you install third party software that runs a x11 server.

[Neumann-A]

only works if you install third party software that runs a x11 server

logically that means it is a feature.

[dg0yt]

The new question is if someone objects to "supports": "!staticcrt", due to only building dynamic libs, effectively excluding x64-windows-static.

[dg0yt]

only works if you install third party software that runs a x11 server

logically that means it is a feature.

Would it be okay to make it opt-in for Linux, too?

[Neumann-A]

Would it be okay to make it opt-in for Linux, too?

Probably:

if get_option('x11_autolaunch').disabled()
    use_x11_autolaunch = false
    x11 = not_found
else
    if get_option('x11_autolaunch').enabled() and platform_windows
        error('X11 autolaunch is not supported on Windows')
    endif

    x11 = dependency('x11', required: false)
    use_x11_autolaunch = x11.found()

    if get_option('x11_autolaunch').enabled() and not use_x11_autolaunch
        error('X11 autolaunch support requested but not found')
    endif
endif
config.set('DBUS_BUILD_X11', use_x11_autolaunch)
config.set('DBUS_ENABLE_X11_AUTOLAUNCH', use_x11_autolaunch)

but this looks like you could get away in ripping out the libx11 dep completely.

[Neumann-A]

Ok for the CMake part:

if(X11_FOUND)
    option(DBUS_BUILD_X11 "Build with X11 autolaunch support " ON)
endif()

maybe ask upstream if it is supported on windows. Seems like it diverged

[dg0yt]

Extra comments:

• AFAICS port dbus is currently not used by any other vcpkg port. However, there are ports with dbus features. There may be installation order problems in those ports.
• On Linux, the port may use (if present) system libsystemd.so which pulls in liblzma.so.5, liblz4.so.1, libgcrypt.so.20 and libgpg-error.so.0 (Ubuntu 18.04). I'm not sure how symbols are resolved when an app uses those libs from vcpkg and dbus.

[BillyONeal]

• On Linux, the port may use (if present) system libsystemd.so which pulls in liblzma.so.5, liblz4.so.1, libgcrypt.so.20 and libgpg-error.so.0 (Ubuntu 18.04). I'm not sure how symbols are resolved when an app uses those libs from vcpkg and dbus.

I don't know if anyone knows :). That said, this PR is clearly an improvement on the status quo, thanks!