[sdl2, sdl2-*] allow disabling transitive dependencies

[ahrbe1]

Is your feature request related to a problem? Please describe.

I recently discovered that on Linux, it seems impossible for users to disable some transitive dependencies of interdependent SDL2 libraries, because the sdl2-* ports depend on "sdl2" which overrides any "default-features": false setting by the user in their vcpkg.json file.

For example, I'd like to build sdl without wayland support, but as soon as I pull in another library, like sdl2-image (which depends on "sdl2"), wayland support is now required.

Similarly, sdl2 has a default dependency on dbus, which has a default dependency on systemd. Systemd needs a lot of external/system packages installed in order to build, so it'd be nice to be able to disable systemd support for dbus in this case.

As I understand, neither of these things are really possible without patching the vcpkg.json port files.

Proposed solution

I would suggest replacing the named "sdl2" dependency with this:

-    "sdl2",
+    {
+      "name": "sdl2",
+      "default-features": false
+    },

for the sdl2-gfx, sdl2-image, sdl2-mixer, sdl2-mixer-ext, sdl2-net, and sdl2-ttf libraries.

and a similar patch for the sdl2 port's dependency on dbus:

     {
       "name": "dbus",
+      "default-features": false,
       "platform": "linux"
     },

Describe alternatives you've considered

I am not aware of any other ways to resolve this issue at the present time due to how default-features work.

Additional context

No response

[chrismile]

First of all, thanks a lot for bringing this up! I am also having problems with sdl2's transitive dependency on systemd via dbus. I tried testing the fixes by @jimwang118 on GitHub actions via

    - name: Setup vcpkg
      uses: lukka/run-vcpkg@v11
      with:
        vcpkgGitURL: 'https://github.com/jimwang118/vcpkg.git'
        vcpkgGitCommitId: 'c9073038fe5313bc8a76982d632ceaf896695597'
        doNotCacheOnWorkflowFailure: true

However, systemd (and in turn libmount) are still fetched even if I use the following vcpkg.json file:

{
    "$schema": "https://raw.githubusercontent.com/microsoft/vcpkg/master/scripts/vcpkg.schema.json",
    "name": "actions-test",
    "version": "0.1.0",
    "dependencies": [
        {
            "name": "dbus",
            "default-features": false,
            "features": [],
            "platform": "linux"
        },
        {
            "name": "sdl2",
            "features": [ "x11", "wayland" ],
            "platform": "linux"
        },
        {
            "name": "sdl2",
            "platform": "!linux"
        },
        "sdl2-image"
    ]
}

Am I using doing something wrong in disabling the transitive dependency on systemd? You can find a test repo reproducing this issue here: https://github.com/chrismile/ActionsTestRepo2

[ahrbe1]

Looking through that MR it patches SDL2PP, but not SDL2. This file also needs patched

https://github.com/microsoft/vcpkg/blob/master/ports/sdl2/vcpkg.json

(Specifically for DBus.)

[jimwang118]

Looking through that MR it patches SDL2PP, but not SDL2. This file also needs patched

https://github.com/microsoft/vcpkg/blob/master/ports/sdl2/vcpkg.json

(Specifically for DBus.)

I don't quite understand what you mean by repairing dbus? Can you elaborate on that? Do I need to add any restrictions to the dbus that sdl2 depends on?

[ahrbe1]

Yes, something like this

--- a/ports/sdl2/vcpkg.json
+++ b/ports/sdl2/vcpkg.json
@@ -8,7 +8,8 @@
   "dependencies": [
     {
       "name": "dbus",
-      "platform": "linux"
+      "platform": "linux",
+      "default-features": false
     },
     {
       "name": "vcpkg-cmake",

[jimwang118]

Yes, something like this

--- a/ports/sdl2/vcpkg.json
+++ b/ports/sdl2/vcpkg.json
@@ -8,7 +8,8 @@
   "dependencies": [
     {
       "name": "dbus",
-      "platform": "linux"
+      "platform": "linux",
+      "default-features": false
     },
     {
       "name": "vcpkg-cmake",

However, vcpkg's dbus does not have default-features, so adding default-features: false has no practical significance.

[ahrbe1]

Really? I see this in the dbus vcpkg.json:

https://github.com/microsoft/vcpkg/blob/master/ports/dbus/vcpkg.json#L20

  "default-features": [
    {
      "name": "systemd",
      "platform": "linux"
    }
  ],

[dg0yt]

dbus[systemd] was added a few days ago.

[jimwang118]

dbus[systemd] was added a few days ago.

Yes, I have not updated the master library locally, so it is not displayed.