Merge 'remotes/trunk'

[0ad.git] / build / premake / extern_libs5.lua

-- this file provides project_add_extern_libs, which takes care of the
-- dirty details of adding the libraries' include and lib paths.
--
-- TYPICAL TASK: add new library. Instructions:
-- 1) add a new extern_lib_defs entry
-- 2) add library name to extern_libs tables in premake.lua for all 'projects' that want to use it

-- directory in which OS-specific library subdirectories reside.
if os.istarget("macosx") then
        libraries_dir = rootdir.."/libraries/osx/"
elseif os.istarget("windows") then
        libraries_dir = rootdir.."/libraries/win32/"
else
        -- No Unix-specific libs yet (use source directory instead!)
end
-- directory for shared, bundled libraries
libraries_source_dir = rootdir.."/libraries/source/"
third_party_source_dir = rootdir.."/source/third_party/"

local function add_default_lib_paths(extern_lib)
        libdirs { libraries_dir .. extern_lib .. "/lib" }
end

local function add_source_lib_paths(extern_lib)
        libdirs { libraries_source_dir .. extern_lib .. "/lib" }
end

local function add_default_include_paths(extern_lib)
        -- As of premake5-beta2, `sysincludedirs` has been deprecated in favour of
        -- `externalincludedirs`, and continuing to use it causes warnings to be emitted.
        --
        -- We use `externalincludedirs` when available to prevent the warnings, falling back
        -- to `sysincludedirs` when not to prevent breakage of the `--with-system-premake5`
        -- build argument.
        if externalincludedirs then
                externalincludedirs { libraries_dir .. extern_lib .. "/include" }
        else
                sysincludedirs { libraries_dir .. extern_lib .. "/include" }
        end
end

local function add_source_include_paths(extern_lib)
        if externalincludedirs then
                externalincludedirs { libraries_source_dir .. extern_lib .. "/include" }
        else
                sysincludedirs { libraries_source_dir .. extern_lib .. "/include" }
        end
end

local function add_third_party_include_paths(extern_lib)
        if externalincludedirs then
                externalincludedirs { third_party_source_dir .. extern_lib .. "/include" }
        else
                sysincludedirs { third_party_source_dir .. extern_lib .. "/include" }
        end
end

pkgconfig = require "pkgconfig"

-- Configure pkgconfig for MacOSX systems
if os.istarget("macosx") then
        pkgconfig.additional_pc_path = libraries_dir .. "pkgconfig/"
        pkgconfig.static_link_libs = true
end

local function add_delayload(name, suffix, def)

        if def["no_delayload"] then
                return
        end

        -- currently only supported by VC; nothing to do on other platforms.
        if not os.istarget("windows") then
                return
        end

        -- no extra debug version; use same library in all configs
        if suffix == "" then
                linkoptions { "/DELAYLOAD:"..name..".dll" }
        -- extra debug version available; use in debug config
        else
                local dbg_cmd = "/DELAYLOAD:" .. name .. suffix .. ".dll"
                local cmd     = "/DELAYLOAD:" .. name .. ".dll"

                filter "Debug"
                        linkoptions { dbg_cmd }
                filter "Release"
                        linkoptions { cmd }
                filter { }
        end

end

local function add_default_links(def)

        -- careful: make sure to only use *_names when on the correct platform.
        local names = {}
        if os.istarget("windows") then
                if def.win_names then
                        names = def.win_names
                end
        elseif _OPTIONS["android"] and def.android_names then
                names = def.android_names
        elseif os.istarget("linux") and def.linux_names then
                names = def.linux_names
        elseif os.istarget("macosx") and (def.osx_names or def.osx_frameworks) then
                if def.osx_names then
                        names = def.osx_names
                end
                -- OS X "Frameworks" are added to the links as "name.framework"
                if def.osx_frameworks then
                        for i,name in pairs(def.osx_frameworks) do
                                links { name .. ".framework" }
                        end
                end
        elseif os.istarget("bsd") and def.bsd_names then
                names = def.bsd_names
        elseif def.unix_names then
                names = def.unix_names
        end

        local suffix = "d"
        -- library is overriding default suffix (typically "" to indicate there is none)
        if def["dbg_suffix"] then
                suffix = def["dbg_suffix"]
        end
        -- non-Windows doesn't have the distinction of debug vs. release libraries
        -- (to be more specific, they do, but the two are binary compatible;
        -- usually only one type - debug or release - is installed at a time).
        if not os.istarget("windows") then
                suffix = ""
        end

        for i,name in pairs(names) do
                filter "Debug"
                        links { name .. suffix }
                filter "Release"
                        links { name }
                filter { }

                add_delayload(name, suffix, def)
        end

end

-- Library definitions
-- In a perfect world, libraries would have a common installation template,
-- i.e. location of include directory, naming convention for .lib, etc.
-- this table provides a means of working around each library's differences.
--
-- The basic approach is defining two functions per library:
--
-- 1. compile_settings
-- This function should set all settings requred during the compile-phase like
-- includedirs, defines etc...
--
-- 2. link_settings
-- This function should set all settings required during the link-phase like
-- libdirs, linkflag etc...
--
-- The main reason for separating those settings is different linking behaviour
-- on osx and xcode. For more details, read the comment in project_add_extern_libs.
--
-- There are some helper functions for the most common tasks. You should use them
-- if they can be used in your situation to make the definitions more consistent and
-- use their default beviours as a guideline.
--
--
-- add_default_lib_paths(extern_lib)
--      Description: Add '<libraries root>/<libraryname>/lib'to the libpaths
--      Parameters:
--          * extern_lib: <libraryname> to be used in the libpath.
--
-- add_default_include_paths(extern_lib)
--      Description: Add '<libraries root>/<libraryname>/include' to the includepaths
--      Parameters:
--          * extern_lib: <libraryname> to be used in the libpath.
--
-- add_default_links
--      Description: Adds links to libraries and configures delayloading.
--      If the *_names parameter for a plattform is missing, no linking will be done
--      on that plattform.
--      The default assumptions are:
--      * debug import library and DLL are distinguished with a "d" suffix
--      * the library should be marked for delay-loading.
--      Parameters:
--      * win_names: table of import library / DLL names (no extension) when
--        running on Windows.
--      * unix_names: as above; shared object names when running on non-Windows.
--      * osx_names, osx_frameworks: for OS X specifically; if any of those is
--        specified, unix_names is ignored. Using both is possible if needed.
--          * osx_names: as above.
--          * osx_frameworks: as above, for system libraries that need to be linked
--            as "name.framework".
--      * bsd_names: as above; for BSD specifically (overrides unix_names if both are
--        specified)
--      * linux_names: ditto for Linux (overrides unix_names if both given)
--      * dbg_suffix: changes the debug suffix from the above default.
--        can be "" to indicate the library doesn't have a debug build;
--        in that case, the same library (without suffix) is used in
--        all build configurations.
--      * no_delayload: indicate the library is not to be delay-loaded.
--        this is necessary for some libraries that do not support it,
--        e.g. Xerces (which is so stupid as to export variables).

extern_lib_defs = {
        boost = {
                compile_settings = function()
                        if os.istarget("windows") then
                                -- Force the autolink to use the vc141 libs.
                                defines { 'BOOST_LIB_TOOLSET="vc141"' }
                                add_default_include_paths("boost")
                        elseif os.istarget("macosx") then
                                -- Suppress all the Boost warnings on OS X by including it as a system directory
                                buildoptions { "-isystem../" .. libraries_dir .. "boost/include" }
                        end
                        -- TODO: This actually applies to most libraries we use on BSDs, make this a global setting.
                        if os.istarget("bsd") then
                                if externalincludedirs then
                                        externalincludedirs { "/usr/local/include" }
                                else
                                        sysincludedirs { "/usr/local/include" }
                                end
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") or os.istarget("macosx") then
                                if os.istarget("windows") then
                                        defines { 'BOOST_LIB_TOOLSET="vc141"' }
                                end
                                add_default_lib_paths("boost")
                        end
                        add_default_links({
                                -- The following are not strictly link dependencies on all systems, but
                                -- are included for compatibility with different versions of Boost
                                android_names = { "boost_filesystem-gcc-mt", "boost_system-gcc-mt" },
                                unix_names = { os.findlib("boost_filesystem-mt") and "boost_filesystem-mt" or "boost_filesystem", os.findlib("boost_system-mt") and "boost_system-mt" or "boost_system" },
                                osx_names = { "boost_filesystem", "boost_system" },
                        })
                end,
        },
        comsuppw = {
                link_settings = function()
                        add_default_links({
                                win_names = { "comsuppw" },
                                dbg_suffix = "d",
                                no_delayload = 1,
                        })
                end,
        },
        cxxtest = {
                compile_settings = function()
                        if externalincludedirs then
                                externalincludedirs { libraries_source_dir .. "cxxtest-4.4" }
                        else
                                sysincludedirs { libraries_source_dir .. "cxxtest-4.4" }
                        end
                end,
        },
        enet = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("enet")
                        else
                                pkgconfig.add_includes("libenet")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("enet")
                                add_default_links({
                                        win_names  = { "enet" },
                                })
                        else
                                pkgconfig.add_links("libenet")
                        end
                end,
        },
        fcollada = {
                compile_settings = function()
                        add_source_include_paths("fcollada")
                end,
                link_settings = function()
                        add_source_lib_paths("fcollada")
                        if os.istarget("windows") then
                                filter "Debug"
                                        links { "FColladaD" }
                                filter "Release"
                                        links { "FCollada" }
                                filter { }
                        else
                                filter "Debug"
                                        links { "FColladaSD" }
                                filter "Release"
                                        links { "FColladaSR" }
                                filter { }
                        end
                end,
        },
        fmt = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("fmt")
                        elseif os.istarget("macosx") then
                                pkgconfig.add_includes("fmt")
                        end

                        -- With Linux & BSD, we assume that fmt is installed in a standard location.
                        --
                        -- It would be nice to not assume, and to instead use pkg-config: however that
                        -- requires fmt 5.3.0 or greater.
                        --
                        -- Unfortunately (at the time of writing) only 92 out of 114 (~80.7%) of distros
                        -- that provide a fmt package meet this, according to
                        -- https://repology.org/badge/vertical-allrepos/fmt.svg?minversion=5.3
                        --
                        -- Whilst that might seem like a healthy majority, this does not include the 2018
                        -- Long Term Support and 2019.10 releases of Ubuntu - not only popular and widely
                        -- used as-is, but which are also used as a base for other popular distros (e.g.
                        -- Mint).
                        --
                        -- When fmt 5.3 (or better) becomes more widely used, then we can safely use the
                        -- same line as we currently use for osx
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("fmt")
                                add_default_links({
                                        win_names = { "fmt" },
                                        dbg_suffix = "d",
                                        no_delayload = 1,
                                })
                        elseif os.istarget("macosx") then
                                -- See comment above as to why this is not also used on Linux or BSD.
                                pkgconfig.add_links("fmt")
                        else
                                add_default_links({
                                        unix_names = { "fmt" },
                                })
                        end
                end
        },
        freetype = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("freetype")
                        else
                                pkgconfig.add_includes("freetype2")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("freetype")
                        else
                                pkgconfig.add_links("freetype2")
                        end
                        add_default_links({
                                win_names = { "freetype" },
                                no_delayload = 1,
                        })
                end,
        },
        glad = {
                add_source_include_paths("glad")
        },
        gloox = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("gloox")
                        else
                                pkgconfig.add_includes("gloox")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("gloox")
                                add_default_links({
                                        win_names  = { "gloox-1.0" },
                                        no_delayload = 1,
                                })
                        else
                                pkgconfig.add_links("gloox")

                                if os.istarget("macosx") then
                                        -- gloox depends on gnutls, but doesn't identify this via pkg-config
                                        pkgconfig.add_links("gnutls")
                                end
                        end
                end,
        },
        iconv = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("iconv")
                                defines { "HAVE_ICONV_CONST" }
                                defines { "ICONV_CONST=const" }
                                defines { "LIBICONV_STATIC" }
                        elseif os.istarget("macosx") then
                                add_default_include_paths("iconv")
                                defines { "LIBICONV_STATIC" }
                        elseif os.getversion().description == "FreeBSD" then
                                -- On FreeBSD you need this flag to tell it to use the BSD libc iconv
                                defines { "LIBICONV_PLUG" }
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") or os.istarget("macosx") then
                                add_default_lib_paths("iconv")
                        end
                        add_default_links({
                                win_names  = { "libiconv" },
                                osx_names = { "iconv" },
                                dbg_suffix = "",
                                no_delayload = 1,
                        })
                        -- glibc (used on Linux and GNU/kFreeBSD) has iconv
                end,
        },
        icu = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("icu")
                        else
                                pkgconfig.add_includes("icu-i18n")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("icu")
                                add_default_links({
                                        win_names  = { "icuuc", "icuin" },
                                        dbg_suffix = "",
                                        no_delayload = 1,
                                })
                        else
                                pkgconfig.add_links("icu-i18n")
                        end
                end,
        },
        libcurl = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("libcurl")
                        else
                                pkgconfig.add_includes("libcurl")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("libcurl")
                        else
                                pkgconfig.add_links("libcurl")
                        end
                        add_default_links({
                                win_names  = { "libcurl" },
                                osx_frameworks = { "Security" }, -- Not supplied by curl's pkg-config
                        })
                end,
        },
        libpng = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("libpng")
                        else
                                pkgconfig.add_includes("libpng")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("libpng")
                                add_default_links({
                                        win_names  = { "libpng16" },
                                })
                        else
                                pkgconfig.add_links("libpng")
                        end
                end,
        },
        libsodium = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("libsodium")
                        else
                                pkgconfig.add_includes("libsodium")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("libsodium")
                                add_default_links({
                                        win_names  = { "libsodium" },
                                })
                        else
                                pkgconfig.add_links("libsodium")
                        end
                end,
        },
        libxml2 = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("libxml2")
                        else
                                pkgconfig.add_includes("libxml-2.0")

                                if os.istarget("macosx") then
                                        -- libxml2 needs _REENTRANT or __MT__ for thread support;
                                        -- OS X doesn't get either set by default, so do it manually
                                        defines { "_REENTRANT" }
                                end
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("libxml2")
                                filter "Debug"
                                        links { "libxml2" }
                                filter "Release"
                                        links { "libxml2" }
                                filter { }
                        else
                                pkgconfig.add_links("libxml-2.0")
                        end
                end,
        },
        miniupnpc = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("miniupnpc")
                        elseif os.istarget("macosx") then
                                pkgconfig.add_includes("miniupnpc")
                        end

                        -- On Linux and BSD systems we assume miniupnpc is installed in a standard location.
                        --
                        -- Support for pkg-config was added in v2.1 of miniupnpc (May 2018). However, the
                        -- implementation was flawed - it provided the wrong path to the project's headers.
                        -- This was corrected in v2.2.1 (December 2020).
                        --
                        -- At the time of writing, of the 123 Linux and BSD package repositories tracked by
                        -- Repology that supply a version of miniupnpc:
                        -- * 88 (~71.54%) have >= v2.1, needed to locate libraries
                        -- * 50 (~40.65%) have >= v2.2.1, needed to (correctly) locate headers
                        --
                        -- Once more recent versions become more widespread, we can safely start to use
                        -- pkg-config to find miniupnpc on Linux and BSD systems.
                        -- https://repology.org/badge/vertical-allrepos/miniupnpc.svg?minversion=2.2.1
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("miniupnpc")
                                add_default_links({
                                        win_names  = { "miniupnpc" },
                                })
                        elseif os.istarget("macosx") then
                                pkgconfig.add_links("miniupnpc")
                        else
                                -- Once miniupnpc v2.1 or better becomes near-universal (see above comment),
                                -- we can use pkg-config for Linux and BSD.
                                add_default_links({
                                        unix_names = { "miniupnpc" },
                                })
                        end
                end,
        },
        nvtt = {
                compile_settings = function()
                        if not _OPTIONS["with-system-nvtt"] then
                                add_source_include_paths("nvtt")
                        end
                        defines { "NVTT_SHARED=1" }
                end,
                link_settings = function()
                        if not _OPTIONS["with-system-nvtt"] then
                                add_source_lib_paths("nvtt")
                        end
                        add_default_links({
                                win_names  = { "nvtt" },
                                unix_names = { "nvcore", "nvmath", "nvimage", "nvtt" },
                                osx_names = { "bc6h", "bc7", "nvcore", "nvimage", "nvmath", "nvthread", "nvtt", "squish" },
                                dbg_suffix = "", -- for performance we always use the release-mode version
                        })
                end,
        },
        openal = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("openal")
                        elseif not os.istarget("macosx") then
                                pkgconfig.add_includes("openal")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("openal")
                                add_default_links({
                                        win_names  = { "openal32" },
                                        dbg_suffix = "",
                                        no_delayload = 1, -- delayload seems to cause errors on startup
                                })
                        elseif os.istarget("macosx") then
                                add_default_links({
                                        osx_frameworks = { "OpenAL" },
                                })
                        else
                                pkgconfig.add_links("openal")
                        end
                end,
        },
        sdl = {
                compile_settings = function()
                        if os.istarget("windows") then
                                includedirs { libraries_dir .. "sdl2/include/SDL" }
                        elseif not _OPTIONS["android"] then
                                pkgconfig.add_includes("sdl2")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("sdl2")
                        elseif not _OPTIONS["android"] then
                                pkgconfig.add_links("sdl2")
                        end
                end,
        },
        spidermonkey = {
                compile_settings = function()
                        if _OPTIONS["with-system-mozjs"] then
                                if not _OPTIONS["android"] then
                                        pkgconfig.add_includes("mozjs-91")
                                end
                        else
                                if os.istarget("windows") then
                                        include_dir = "include-win32"
                                else
                                        include_dir = "include-unix"
                                end
                                filter "Debug"
                                        if externalincludedirs then
                                                externalincludedirs { libraries_source_dir.."spidermonkey/"..include_dir.."-debug" }
                                        else
                                                sysincludedirs { libraries_source_dir.."spidermonkey/"..include_dir.."-debug" }
                                        end
                                        defines { "DEBUG" }
                                filter "Release"
                                        if externalincludedirs then
                                                externalincludedirs { libraries_source_dir.."spidermonkey/"..include_dir.."-release" }
                                        else
                                                sysincludedirs { libraries_source_dir.."spidermonkey/"..include_dir.."-release" }
                                        end
                                filter { }
                        end
                end,
                link_settings = function()
                        if _OPTIONS["with-system-mozjs"] then
                                if _OPTIONS["android"] then
                                        links { "mozjs-91" }
                                else
                                        pkgconfig.add_links("mozjs-91")
                                end
                        else
                                filter { "Debug", "action:vs*" }
                                        links { "mozjs91-ps-debug" }
                                        links { "mozjs91-ps-rust-debug" }
                                filter { "Debug", "action:not vs*" }
                                        links { "mozjs91-ps-debug" }
                                        links { "mozjs91-ps-rust" }
                                filter { "Release" }
                                        links { "mozjs91-ps-release" }
                                        links { "mozjs91-ps-rust" }
                                filter { }
                                add_source_lib_paths("spidermonkey")
                        end
                end,
        },
        tinygettext = {
                compile_settings = function()
                        add_third_party_include_paths("tinygettext")
                end,
        },
        valgrind = {
                compile_settings = function()
                        -- Optional dependency
                        --
                        -- valgrind doesn't support windows:
                        --   https://valgrind.org/info/platforms.html
                        if _OPTIONS["with-valgrind"] and not os.istarget("windows") then
                                pkgconfig.add_includes("valgrind")
                                defines { "CONFIG2_VALGRIND=1" }
                        end
                end,
        },
        vorbis = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("vorbis")
                        else
                                pkgconfig.add_includes("ogg")
                                pkgconfig.add_includes("vorbisfile")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("vorbis")
                                add_default_links({
                                        win_names  = { "libvorbisfile" },
                                })
                        elseif os.getversion().description == "OpenBSD" then
                                -- TODO: We need to force linking with these as currently
                                -- they need to be loaded explicitly on execution
                                add_default_links({
                                        unix_names = { "ogg", "vorbis" },
                                })
                        else
                                pkgconfig.add_links("vorbisfile")
                        end
                end,
        },
        wxwidgets = {
                compile_settings = function()
                        if os.istarget("windows") then
                                includedirs { libraries_dir.."wxwidgets/include/msvc" }
                                add_default_include_paths("wxwidgets")
                        else
                                -- wxwidgets does not come with a definition file for pkg-config,
                                -- so we have to use wxwidgets' own config tool
                                wx_config_path = os.getenv("WX_CONFIG") or "wx-config"
                                pkgconfig.add_includes(nil, wx_config_path, "--unicode=yes --cxxflags")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                libdirs { libraries_dir.."wxwidgets/lib/vc_lib" }
                        else
                                wx_config_path = os.getenv("WX_CONFIG") or "wx-config"
                                pkgconfig.add_links(nil, wx_config_path, "--unicode=yes --libs std,gl")
                        end
                end,
        },
        x11 = {
                compile_settings = function()
                        if not os.istarget("windows") and not os.istarget("macosx") then
                                pkgconfig.add_includes("x11")
                        end
                end,
                link_settings = function()
                        if not os.istarget("windows") and not os.istarget("macosx") then
                                pkgconfig.add_links("x11")
                        end
                end,
        },
        zlib = {
                compile_settings = function()
                        if os.istarget("windows") then
                                add_default_include_paths("zlib")
                        else
                                pkgconfig.add_includes("zlib")
                        end
                end,
                link_settings = function()
                        if os.istarget("windows") then
                                add_default_lib_paths("zlib")
                                add_default_links({
                                        win_names  = { "zlib1" },
                                        no_delayload = 1,
                                })
                        else
                                pkgconfig.add_links("zlib")
                        end
                end,
        },
}


-- add a set of external libraries to the project; takes care of
-- include / lib path and linking against the import library.
-- extern_libs: table of library names [string]
-- target_type: String defining the projects kind [string]
function project_add_extern_libs(extern_libs, target_type)

        for i,extern_lib in pairs(extern_libs) do
                local def = extern_lib_defs[extern_lib]
                assert(def, "external library " .. extern_lib .. " not defined")

                if def.compile_settings then
                        def.compile_settings()
                end

                -- Linking to external libraries will only be done in the main executable and not in the
                -- static libraries. Premake would silently skip linking into static libraries for some
                -- actions anyway (e.g. vs2010).
                -- On osx using xcode, if this linking would be defined in the static libraries, it would fail to
                -- link if only dylibs are available. If both *.a and *.dylib are available, it would link statically.
                -- I couldn't find any problems with that approach.
                if target_type ~= "StaticLib" and def.link_settings then
                        def.link_settings()
                end
        end
end