/// A marker trait saying that something is a label for a particular backend,
/// with associated gfx-rs types for that backend.
pub trait BackendSpec {
    /// Surface type
    type SurfaceType: gfx::format::Formatted;
    /// gfx resource type
    type Resources: gfx::Resources;
    /// gfx factory type
    type Factory: gfx::Factory<Self::Resources>;
    /// gfx command buffer type
    type CommandBuffer: gfx::CommandBuffer<Self::Resources>;
    /// gfx device type
    type Device: gfx::Device<Resources = Self::Resources, CommandBuffer = Self::CommandBuffer>;

    /// A helper function to take a RawShaderResourceView and turn it into a typed one based on
    /// the surface type defined in a `BackendSpec`
    fn raw_to_typed_shader_resource(texture_view: gfx::handle::RawShaderResourceView<Self::Resources>)
                                       -> gfx::handle::ShaderResourceView<Self::Resources, [f32;4]> {
        type ShaderType = <Self::SurfaceType as gfx::format::Formatted>::View;
        let typed_view: gfx::handle::ShaderResourceView<_, ShaderType> = gfx::memory::Typed::new(texture_view);
        typed_view
    }
}

// raw_to_typed_resource fails to compile with the message:
/*
error[E0401]: can't use type parameters from outer function
  --> src/graphics/mod.rs:69:29
   |
67 |     fn raw_to_typed_shader_resource(texture_view: gfx::handle::RawShaderResourceView<Self::Resources>)
   |        ---------------------------- try adding a local type parameter in this method instead
68 |                                        -> gfx::handle::ShaderResourceView<Self::Resources, [f32;4]> {
69 |         type ShaderType2 = <Self::SurfaceType as gfx::format::Formatted>::View;
   |                             ^^^^^^^^^^^^^^^^^ use of type variable from outer function

*/


fn main() {

}