Separate supertrait collection from processing a TraitDef. This allows

us to construct trait-references and do other things without forcing a
full evaluation of the supertraits. One downside of this scheme is that
we must invoke `ensure_super_predicates` before using any construct that
might require knowing about the super-predicates.

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

@@ -25,7 +25,7 @@ trait Trait { type Item; }
 struct A<T>
     where T : Trait,
           T : Add<T::Item>
-    //~^ ERROR illegal recursive type
+    //~^ ERROR unsupported cyclic reference between types/traits detected
 {
     data: T
 }

src/test/compile-fail/cycle-trait-default-type-trait.rs

@@ -1,4 +1,4 @@
-// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// 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.
 //
@@ -8,8 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-trait Foo {}
+// Test a cycle where a type parameter on a trait has a default that
+// again references the trait.
 
-fn foo<T: Foo + Foo>() {} //~ ERROR `Foo` already appears in the list of bounds
+trait Foo<X = Box<Foo>> {
+    //~^ ERROR unsupported cyclic reference
+}
 
-fn main() {}
+fn main() { }

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

@@ -12,9 +12,12 @@
 // a direct participant in the cycle.
 
 trait A: B {
+    //~^ ERROR unsupported cyclic reference
 }
 
-trait B: C { }
+trait B: C {
+    //~^ ERROR unsupported cyclic reference
+}
 
 trait C: B { }
     //~^ ERROR unsupported cyclic reference

src/test/compile-fail/infinite-vec-type-recursion.rs

@@ -8,9 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// error-pattern: illegal recursive type
-
-
 type x = Vec<x>;
+//~^ ERROR unsupported cyclic reference
 
 fn main() { let b: x = Vec::new(); }

src/test/compile-fail/issue-18389.rs

@@ -12,18 +12,17 @@
 
 use std::any::Any;
 use std::any::TypeId;
+use std::marker::MarkerTrait;
 
-pub trait Pt {}
-pub trait Rt {}
+pub trait Pt : MarkerTrait {}
+pub trait Rt : MarkerTrait {}
 
 trait Private<P: Pt, R: Rt> {
     fn call(&self, p: P, r: R);
 }
-pub trait Public: Private<
+pub trait Public: Private< //~ ERROR private trait in exported type parameter bound
     <Self as Public>::P,
-//~^ ERROR illegal recursive type; insert an enum or struct in the cycle, if this is desired
     <Self as Public>::R
-//~^ ERROR unsupported cyclic reference between types/traits detected
 > {
     type P;
     type R;

src/test/compile-fail/issue-3953.rs

@@ -13,7 +13,6 @@
 use std::cmp::PartialEq;
 
 trait Hahaha: PartialEq + PartialEq {
-    //~^ ERROR trait `PartialEq` already appears in the list of bounds
 }
 
 struct Lol(isize);
@@ -21,8 +20,8 @@ struct Lol(isize);
 impl Hahaha for Lol { }
 
 impl PartialEq for Lol {
-    fn eq(&self, other: &Lol) -> bool { **self != **other }
-    fn ne(&self, other: &Lol) -> bool { **self == **other }
+    fn eq(&self, other: &Lol) -> bool { loop { } }
+    fn ne(&self, other: &Lol) -> bool { loop { } }
 }
 
 fn main() {