Improve to find system/3rd package for add_requires/find_package.lua in package definition

[waruqi]

We can improve the builin find_package script in add_requires to support to find more system/3rd package in other package managers.

Example (libusb)

for apt and some linux systems, it is libusb-1.0

But, we always use libusb as package name to find and use it:

add_requires("libusb")
target("test")
    set_kind("binary")
    add_files("src/*.c")
    add_packages("libusb")

for find_package, it always be libusb.

xmake l find_package libusb

Solution

package("libusb")
    -- pacman::xxx, brew::xxx ...
    add_extsources("pkg_config::libusb-1.0", "conan::libusb")

related issue: #1140

[waruqi]

I added add_extsources() to add external package sources on dev branch. #1248

add_extsources("pkgconfig::libusb-1.0")

And I have improved xmake-repo/libusb to support it.

https://github.com/xmake-io/xmake-repo/blob/66f5ae98c44320a33275f2ac782effd5b87298f0/packages/l/libusb/xmake.lua#L25-L27

[waruqi]

on_fetch has been supported.

package("libusb")
    on_fetch("linux", function(package, opt)
        if opt.system then
            return find_package("pkgconfig::libusb-1.0")
        end
    end)