Auto merge of #21237 - erickt:derive-assoc-types, r=erickt

This PR adds support for associated types to the `#[derive(...)]` syntax extension. In order to do this, it switches over to using where predicates to apply the type constraints. So now this:

```rust
type Trait {
    type Type;
}

#[derive(Clone)]
struct Foo<A> where A: Trait {
    a: A,
    b: <A as Trait>::Type,
}
```

Gets expended into this impl:

```rust
impl<A: Clone> Clone for Foo<A> where
    A: Trait,
    <A as Trait>::Type: Clone,
{
    fn clone(&self) -> Foo<T> {
        Foo {
            a: self.a.clone(),
            b: self.b.clone(),
        }
    }
}
```

3 files changed, 240 insertions, 0 deletions

diff --git a/src/test/auxiliary/struct_variant_xc_aux.rs b/src/test/auxiliary/struct_variant_xc_aux.rs
index 76fd619f689..8670cd96fc6 100644
--- a/src/test/auxiliary/struct_variant_xc_aux.rs
+++ b/src/test/auxiliary/struct_variant_xc_aux.rs
@@ -11,6 +11,7 @@
 #![crate_name="struct_variant_xc_aux"]
 #![crate_type = "lib"]
 
+#[derive(Copy)]
 pub enum Enum {
     Variant(u8),
     StructVariant { arg: u8 }
diff --git a/src/test/compile-fail/derive-assoc-type-not-impl.rs b/src/test/compile-fail/derive-assoc-type-not-impl.rs
new file mode 100644
index 00000000000..3799f2ffba4
--- /dev/null
+++ b/src/test/compile-fail/derive-assoc-type-not-impl.rs
@@ -0,0 +1,29 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+trait Foo {
+    type X;
+    fn method(&self) {}
+}
+
+#[derive(Clone)]
+struct Bar<T: Foo> {
+    x: T::X,
+}
+
+struct NotClone;
+
+impl Foo for NotClone {
+    type X = i8;
+}
+
+fn main() {
+    Bar::<NotClone> { x: 1 }.clone(); //~ ERROR
+}
diff --git a/src/test/run-pass/deriving-associated-types.rs b/src/test/run-pass/deriving-associated-types.rs
new file mode 100644
index 00000000000..59eb5506c45
--- /dev/null
+++ b/src/test/run-pass/deriving-associated-types.rs
@@ -0,0 +1,210 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(core, debug_builders)]
+
+pub trait DeclaredTrait {
+    type Type;
+}
+
+impl DeclaredTrait for i32 {
+    type Type = i32;
+}
+
+pub trait WhereTrait {
+    type Type;
+}
+
+impl WhereTrait for i32 {
+    type Type = i32;
+}
+
+// Make sure we don't add a bound that just shares a name with an associated
+// type.
+pub mod module {
+    pub type Type = i32;
+}
+
+#[derive(PartialEq, Debug)]
+struct PrivateStruct<T>(T);
+
+#[derive(PartialEq, Debug)]
+struct TupleStruct<A, B: DeclaredTrait, C>(
+    module::Type,
+    Option<module::Type>,
+    A,
+    PrivateStruct<A>,
+    B,
+    B::Type,
+    Option<B::Type>,
+    <B as DeclaredTrait>::Type,
+    Option<<B as DeclaredTrait>::Type>,
+    C,
+    C::Type,
+    Option<C::Type>,
+    <C as WhereTrait>::Type,
+    Option<<C as WhereTrait>::Type>,
+    <i32 as DeclaredTrait>::Type,
+) where C: WhereTrait;
+
+#[derive(PartialEq, Debug)]
+pub struct Struct<A, B: DeclaredTrait, C> where C: WhereTrait {
+    m1: module::Type,
+    m2: Option<module::Type>,
+    a1: A,
+    a2: PrivateStruct<A>,
+    b: B,
+    b1: B::Type,
+    b2: Option<B::Type>,
+    b3: <B as DeclaredTrait>::Type,
+    b4: Option<<B as DeclaredTrait>::Type>,
+    c: C,
+    c1: C::Type,
+    c2: Option<C::Type>,
+    c3: <C as WhereTrait>::Type,
+    c4: Option<<C as WhereTrait>::Type>,
+    d: <i32 as DeclaredTrait>::Type,
+}
+
+#[derive(PartialEq, Debug)]
+enum Enum<A, B: DeclaredTrait, C> where C: WhereTrait {
+    Unit,
+    Seq(
+        module::Type,
+        Option<module::Type>,
+        A,
+        PrivateStruct<A>,
+        B,
+        B::Type,
+        Option<B::Type>,
+        <B as DeclaredTrait>::Type,
+        Option<<B as DeclaredTrait>::Type>,
+        C,
+        C::Type,
+        Option<C::Type>,
+        <C as WhereTrait>::Type,
+        Option<<C as WhereTrait>::Type>,
+        <i32 as DeclaredTrait>::Type,
+    ),
+    Map {
+        m1: module::Type,
+        m2: Option<module::Type>,
+        a1: A,
+        a2: PrivateStruct<A>,
+        b: B,
+        b1: B::Type,
+        b2: Option<B::Type>,
+        b3: <B as DeclaredTrait>::Type,
+        b4: Option<<B as DeclaredTrait>::Type>,
+        c: C,
+        c1: C::Type,
+        c2: Option<C::Type>,
+        c3: <C as WhereTrait>::Type,
+        c4: Option<<C as WhereTrait>::Type>,
+        d: <i32 as DeclaredTrait>::Type,
+    },
+}
+
+fn main() {
+    let e: TupleStruct<
+        i32,
+        i32,
+        i32,
+    > = TupleStruct(
+        0,
+        None,
+        0,
+        PrivateStruct(0),
+        0,
+        0,
+        None,
+        0,
+        None,
+        0,
+        0,
+        None,
+        0,
+        None,
+        0,
+    );
+    assert_eq!(e, e);
+
+    let e: Struct<
+        i32,
+        i32,
+        i32,
+    > = Struct {
+        m1: 0,
+        m2: None,
+        a1: 0,
+        a2: PrivateStruct(0),
+        b: 0,
+        b1: 0,
+        b2: None,
+        b3: 0,
+        b4: None,
+        c: 0,
+        c1: 0,
+        c2: None,
+        c3: 0,
+        c4: None,
+        d: 0,
+    };
+    assert_eq!(e, e);
+
+    let e = Enum::Unit::<i32, i32, i32>;
+    assert_eq!(e, e);
+
+    let e: Enum<
+        i32,
+        i32,
+        i32,
+    > = Enum::Seq(
+        0,
+        None,
+        0,
+        PrivateStruct(0),
+        0,
+        0,
+        None,
+        0,
+        None,
+        0,
+        0,
+        None,
+        0,
+        None,
+        0,
+    );
+    assert_eq!(e, e);
+
+    let e: Enum<
+        i32,
+        i32,
+        i32,
+    > = Enum::Map {
+        m1: 0,
+        m2: None,
+        a1: 0,
+        a2: PrivateStruct(0),
+        b: 0,
+        b1: 0,
+        b2: None,
+        b3: 0,
+        b4: None,
+        c: 0,
+        c1: 0,
+        c2: None,
+        c3: 0,
+        c4: None,
+        d: 0,
+    };
+    assert_eq!(e, e);
+}