rustc: store type parameter defaults outside of ty::Generics.

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

@@ -13,6 +13,7 @@
 
 trait Foo<X = Box<Foo>> {
     //~^ ERROR unsupported cyclic reference
+    //~| ERROR unsupported cyclic reference
 }
 
 fn main() { }

src/test/compile-fail/generic-non-trailing-defaults.rs

@@ -10,10 +10,10 @@
 
 struct Heap;
 
-struct Vec<A = Heap, T>;
+struct Vec<A = Heap, T>(A, T);
 //~^ ERROR type parameters with a default must be trailing
 
-struct Foo<A, B = Vec<C>, C>;
+struct Foo<A, B = Vec<C>, C>(A, B, C);
 //~^ ERROR type parameters with a default must be trailing
 //~| ERROR type parameters with a default cannot use forward declared identifiers
 

src/test/compile-fail/generic-type-params-forward-mention.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 // Ensure that we get an error and not an ICE for this problematic case.
-struct Foo<T = Option<U>, U = bool>;
+struct Foo<T = Option<U>, U = bool>(T, U);
 //~^ ERROR type parameters with a default cannot use forward declared identifiers
 fn main() {
     let x: Foo;

src/test/compile-fail/issue-18183.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-pub struct Foo<Bar=Bar>; //~ ERROR E0128
-                         //~| NOTE defaulted type parameters cannot be forward declared
+pub struct Foo<Bar=Bar>(Bar); //~ ERROR E0128
+                              //~| NOTE defaulted type parameters cannot be forward declared
 pub struct Baz(Foo);
 fn main() {}

src/test/compile-fail/resolve-self-in-impl.rs

@@ -15,7 +15,7 @@ impl Tr<Self> for S {} // OK
 
 // FIXME: `Self` cannot be used in bounds because it depends on bounds itself.
 impl<T: Tr<Self>> Tr<T> for S {} //~ ERROR `Self` type is used before it's determined
-impl<T = Self> Tr<T> for S {} //~ ERROR `Self` type is used before it's determined
+impl<T = Self> Tr<T> for S {}
 impl Tr for S where Self: Copy {} //~ ERROR `Self` type is used before it's determined
 impl Tr for S where S<Self>: Copy {} //~ ERROR `Self` type is used before it's determined
 impl Tr for S where Self::Assoc: Copy {} //~ ERROR `Self` type is used before it's determined