How to define a new platform and target kind?

[davidchisnall]

The docs on defining a new toolchain are very clear but even after spending a morning reading the code I'm not clear how to define:

• A new platform
• A new target kind

I've tried using platform("my platform name") but this errors out that platform is nil. I can use set_kind("any string") in the target definition but I can't then see how to define rules for this kind of target (for example, inheriting the existing C/C++ compile rules but providing a different link step).

Edit: I have found the undocumented top-level add_platformdirs command and now my platform is being loaded. It appears that set_os is required here, because link steps are silently fail to run if it is not called.

[waruqi]

You can't define them directly, but you can use any platform name.

if is_plat("myplat") then
    add_defines("xxx")
end

xmake f -p myplat
xmake

you can also use custom rule.

rule("myplat")
    on_load(function (target)
        if target:is_plat("myplat") then
            target:add("defines", "xxx")
        end
    end)
rule_end()

target("test")
    add_rules("myplat")
    -- ...

xmake f -p myplat
xmake

and you can put your platform rules to myplatforms/xmake.lua and use includes("myplatforms") to import them.

[davidchisnall]

It appears that if I put them in platforms/{my platform}/xmake.lua and then do add_platformdirs("platforms") then my platform is loaded and applied correctly.

For the custom target kinds, I can do set_kind("{whatever"}), but then none of the default rules run. Is there a mechanism for me to, for example, import all of the generic compile rules for that kind but provide custom linking rules?

[waruqi]

It appears that if I put them in platforms/{my platform}/xmake.lua and then do add_platformdirs("platforms") then my platform is loaded and applied correctly.

The platform() interfaces are not yet open for customisation, so I don't have them documented at the moment. As the platform api design is not fully stable yet, I may change them at any time.

Although the add_platformdirs interface is available, I don't recommend that you use it now, please try to customise the platform using the custom rule pattern I mentioned above.

For the custom target kinds, I can do set_kind("{whatever"}), but then none of the default rules run. Is there a mechanism for me to, for example, import all of the generic compile rules for that kind but provide custom linking rules?

We can't customize kind, you can only use binary/static/shared/headeronly/phony, you should use custom rules to extend kind.

for example: mykind rule

rule("mykind")
    on_load(function (target)
         target:set("kind", "binary")
         target:add("defines", "xxx")
    end)
rule_end()

target("test")
     add_rules("mykind")

see

xmake/xmake/rules/qt/xmake.lua

Line 40 in 1acf248

rule("qt.static")

xmake/xmake/rules/mdk/xmake.lua

Line 34 in 1acf248

rule("mdk.static")

[waruqi]

You can always use custom rule to achieve everything you need, including custom platforms and kind

[davidchisnall]

Thanks! add_deps doesn't seem to be documented in the custom rules section (it is used in one example, but I missed it). It seems to be the thing that was missing for me to be able to do most of the things that I want.

The other thing that I didn't really understand from the docs is that each of the set_{thing} methods in the target scope corresponded to target:set("{thing}", ...) in the script scope. It would be good if the docs could make that explicit.