vkd3d-shader: Introduce VKD3D_SHADER_TARGET_MSL.

Approved-by: Giovanni Mascellani (@giomasce)
Approved-by: Henri Verbeet (@hverbeet)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/1055

libs/vkd3d-shader/msl.c

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2024 Feifan He for CodeWeavers
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#include "vkd3d_shader_private.h"
+
+int msl_compile(struct vkd3d_shader_message_context *message_context)
+{
+    MESSAGE("Generating a MSL shader. This is unsupported; you get to keep all the pieces if it breaks.\n");
+
+    vkd3d_shader_error(message_context, NULL, VKD3D_SHADER_ERROR_MSL_INTERNAL,
+            "Internal compiler error: Unhandled instruction.");
+
+    return VKD3D_ERROR_INVALID_SHADER;
+}