Remove gfx import in pipeline macro

[msiglreith]

As RFC 1560 (rust-lang/rfcs#1560) is now stabilized on nightly 1.14.0 use super::* will now import all occurences of use gfx; from the parent module. This allows to compile code like following:

#[macro_use]
extern crate gfx as gfx_temp;

mod foo {
    // Import `gfx` into this module.
    // The new pipeline module created in the macro has access
    // to this import via `use super::*;`
    use gfx_temp; 

    gfx_defines!{
        vertex Vertex {
            pos: [f32; 4] = "a_Pos",
            tex_coord: [f32; 2] = "a_TexCoord",
        }

        pipeline pipe {
            vbuf: gfx_temp::VertexBuffer<Vertex> = (),
        }
    }
}

So as long as the gfx module is imported in the module where you define the pipeline everything should work. Following this condition the regression #1070 would be resolved.

[msiglreith]

Is there an option for conditional compilation depening on rustc version? Rust compiler <1.14.0 still require the use $crates; approach, while newer versions would make use of the item_like_imports feature.

[kvark]

Hmm. Everything is great, except that it doesn't build on Linux stable (according to Travis)...

[msiglreith]

Rust stable is still 1.13.0 which doesn't support item_like_imports and still requires the legacy use $crates; way. 1.14.0 will go out of beta around end of december.

[sectopod]

Is this still needed? I was under impression that gfx now compiles fine on nightly/stable

[msiglreith]

I think the example above won't compile with the current master branch, but I can double-check this!
1.14 is scheduled to become stable at 22nd december, then this PR should also build without problems on stable.

[kvark]

@msiglreith ok, so you are saying we should be safe to merge this for 1.14? We'd also need to update the appveyor to use the new version.

[msiglreith]

@kvark Yes, but I'll try to check other projects (e.g zoc) if this might cause some issues.

[msiglreith]

Hm, looks like the item_like_imports feature didn't make it into the stable release. Closing this for the moment and create a new PR, when it finally becomes active in the stable channel.