Rework trait-bound-conversion so be based on the AST and rework collect

to pass in the appropriate ast::generics etc

src/librustc/metadata/tydecode.rs

@@ -835,6 +835,22 @@ fn parse_type_param_def_<'a, 'tcx, F>(st: &mut PState<'a, 'tcx>, conv: &mut F)
     }
 }
 
+fn parse_object_lifetime_default<'a,'tcx, F>(st: &mut PState<'a,'tcx>,
+                                             conv: &mut F)
+                                             -> Option<ty::ObjectLifetimeDefault>
+    where F: FnMut(DefIdSource, ast::DefId) -> ast::DefId,
+{
+    match next(st) {
+        'n' => None,
+        'a' => Some(ty::ObjectLifetimeDefault::Ambiguous),
+        's' => {
+            let region = parse_region_(st, conv);
+            Some(ty::ObjectLifetimeDefault::Specific(region))
+        }
+        _ => panic!("parse_object_lifetime_default: bad input")
+    }
+}
+
 fn parse_existential_bounds<'a,'tcx, F>(st: &mut PState<'a,'tcx>,
                                         mut conv: F)
                                         -> ty::ExistentialBounds<'tcx> where

src/test/compile-fail/associated-type-projection-ambig-between-bound-and-where-clause.rs

@@ -0,0 +1,52 @@
+// Copyright 2014 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.
+
+// Test equality constraints in a where clause where the type being
+// equated appears in a supertrait.
+
+pub trait Vehicle {
+    type Color;
+
+    fn go(&self) {  }
+}
+
+pub trait Box {
+    type Color;
+
+    fn mail(&self) {  }
+}
+
+fn a<C:Vehicle+Box>(_: C::Color) {
+    //~^ ERROR ambiguous associated type `Color` in bounds of `C`
+}
+
+fn b<C>(_: C::Color) where C : Vehicle+Box {
+    //~^ ERROR ambiguous associated type `Color` in bounds of `C`
+}
+
+fn c<C>(_: C::Color) where C : Vehicle, C : Box {
+    //~^ ERROR ambiguous associated type `Color` in bounds of `C`
+}
+
+struct D<X>;
+impl<X> D<X> where X : Vehicle {
+    fn d(&self, _: X::Color) where X : Box { }
+    //~^ ERROR ambiguous associated type `Color` in bounds of `X`
+}
+
+trait E<X:Vehicle> {
+    fn e(&self, _: X::Color) where X : Box;
+    //~^ ERROR ambiguous associated type `Color` in bounds of `X`
+
+    fn f(&self, _: X::Color) where X : Box { }
+    //~^ ERROR ambiguous associated type `Color` in bounds of `X`
+}
+
+pub fn main() { }

src/test/compile-fail/cycle-projection-based-on-where-clause.rs

@@ -0,0 +1,34 @@
+// 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.
+
+// Example cycle where a bound on `T` uses a shorthand for `T`. This
+// creates a cycle because we have to know the bounds on `T` to figure
+// out what trait defines `Item`, but we can't know the bounds on `T`
+// without knowing how to handle `T::Item`.
+//
+// Note that in the future cases like this could perhaps become legal,
+// if we got more fine-grained about our cycle detection or changed
+// how we handle `T::Item` resolution.
+
+use std::ops::Add;
+
+// Preamble.
+trait Trait { type Item; }
+
+struct A<T>
+    where T : Trait,
+          T : Add<T::Item>
+    //~^ ERROR illegal recursive type
+{
+    data: T
+}
+
+fn main() {
+}

src/test/compile-fail/cycle-trait-supertrait-direct.rs

@@ -11,7 +11,7 @@
 // Test a supertrait cycle where a trait extends itself.
 
 trait Chromosome: Chromosome {
-    //~^ ERROR cyclic reference detected
+    //~^ ERROR unsupported cyclic reference
 }
 
 fn main() { }

src/test/compile-fail/cycle-trait-supertrait-indirect.rs

@@ -15,8 +15,8 @@ trait A: B {
 }
 
 trait B: C { }
-    //~^ ERROR cyclic reference detected
 
 trait C: B { }
+    //~^ ERROR unsupported cyclic reference
 
 fn main() { }

src/test/run-pass/associated-types-project-from-type-param-via-bound-in-where-clause.rs

@@ -0,0 +1,107 @@
+// 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.
+
+// Various uses of `T::Item` syntax where the bound that supplies
+// `Item` originates in a where-clause, not the declaration of
+// `T`. Issue #20300.
+
+use std::marker::{MarkerTrait, PhantomData};
+use std::sync::atomic::{AtomicUsize, ATOMIC_USIZE_INIT};
+use std::sync::atomic::Ordering::SeqCst;
+
+static COUNTER: AtomicUsize = ATOMIC_USIZE_INIT;
+
+// Preamble.
+trait Trait : MarkerTrait { type Item; }
+struct Struct;
+impl Trait for Struct {
+    type Item = u32;
+}
+
+// Where-clause attached on the method which declares `T`.
+struct A;
+impl A {
+    fn foo<T>(_x: T::Item) where T: Trait {
+        COUNTER.fetch_add(1, SeqCst);
+    }
+}
+
+// Where-clause attached on the method to a parameter from the struct.
+struct B<T>(PhantomData<T>);
+impl<T> B<T> {
+    fn foo(_x: T::Item) where T: Trait {
+        COUNTER.fetch_add(10, SeqCst);
+    }
+}
+
+// Where-clause attached to free fn.
+fn c<T>(_: T::Item) where T : Trait {
+    COUNTER.fetch_add(100, SeqCst);
+}
+
+// Where-clause attached to defaulted and non-defaulted trait method.
+trait AnotherTrait {
+    fn method<T>(&self, _: T::Item) where T: Trait;
+    fn default_method<T>(&self, _: T::Item) where T: Trait {
+        COUNTER.fetch_add(1000, SeqCst);
+    }
+}
+struct D;
+impl AnotherTrait for D {
+    fn method<T>(&self, _: T::Item) where T: Trait {
+        COUNTER.fetch_add(10000, SeqCst);
+    }
+}
+
+// Where-clause attached to trait and impl containing the method.
+trait YetAnotherTrait<T>
+    where T : Trait
+{
+    fn method(&self, _: T::Item);
+    fn default_method(&self, _: T::Item) {
+        COUNTER.fetch_add(100000, SeqCst);
+    }
+}
+struct E<T>(PhantomData<T>);
+impl<T> YetAnotherTrait<T> for E<T>
+    where T : Trait
+{
+    fn method(&self, _: T::Item) {
+        COUNTER.fetch_add(1000000, SeqCst);
+    }
+}
+
+// Where-clause attached to inherent impl containing the method.
+struct F<T>(PhantomData<T>);
+impl<T> F<T> where T : Trait {
+    fn method(&self, _: T::Item) {
+        COUNTER.fetch_add(10000000, SeqCst);
+    }
+}
+
+// Where-clause attached to struct.
+#[allow(dead_code)]
+struct G<T> where T : Trait {
+    data: T::Item,
+    phantom: PhantomData<T>,
+}
+
+fn main() {
+    A::foo::<Struct>(22);
+    B::<Struct>::foo(22);
+    c::<Struct>(22);
+    D.method::<Struct>(22);
+    D.default_method::<Struct>(22);
+    E(PhantomData::<Struct>).method(22);
+    E(PhantomData::<Struct>).default_method(22);
+    F(PhantomData::<Struct>).method(22);
+    G::<Struct> { data: 22, phantom: PhantomData };
+    assert_eq!(COUNTER.load(SeqCst), 11111111);
+}

src/test/compile-fail/cycle-generic-bound.rs → src/test/run-pass/cycle-generic-bound.rs

@@ -8,12 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Regression test for #15477. This test should pass, vs reporting an
-// error as it does now, but at least this test shows it doesn't
-// segfault.
+// Regression test for #15477. This test just needs to compile.
 
-trait Chromosome<X: Chromosome> {
-    //~^ ERROR cyclic reference detected
+use std::marker::PhantomFn;
+
+trait Chromosome<X: Chromosome<i32>> : PhantomFn<(Self,X)> {
 }
 
 fn main() { }

src/test/compile-fail/cycle-trait-type-trait.rs → src/test/run-pass/cycle-trait-type-trait.rs

@@ -8,10 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Test a supertrait cycle where a trait extends itself.
+// Test a case where a supertrait references a type that references
+// the original trait. This poses no problem at the moment.
 
-trait Chromosome: Get<Struct> {
-    //~^ ERROR cyclic reference detected
+trait Chromosome: Get<Struct<i32>> {
 }
 
 trait Get<A> {