Remove subtle Default impl for Value

Author: Zoxc

src/librustc/ty/query/values.rs

@@ -14,12 +14,6 @@ impl<'tcx, T> Value<'tcx> for T {
     }
 }
 
-impl<'tcx, T: Default> Value<'tcx> for T {
-    default fn from_cycle_error<'a>(_: TyCtxt<'a, 'tcx, 'tcx>) -> T {
-        T::default()
-    }
-}
-
 impl<'tcx> Value<'tcx> for Ty<'tcx> {
     fn from_cycle_error<'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Ty<'tcx> {
         tcx.types.err

src/test/incremental/cyclic-trait-hierarchy.rs

@@ -7,7 +7,6 @@ pub trait T2 { }
 #[cfg(cfail2)]
 pub trait T2: T1 { }
 //[cfail2]~^ ERROR cycle detected when computing the supertraits of `T2`
-//[cfail2]~| ERROR cycle detected when computing the supertraits of `T2`
 
 pub trait T1: T2 { }
 

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

@@ -16,7 +16,6 @@ struct A<T>
     where T : Trait,
           T : Add<T::Item>
     //~^ ERROR cycle detected
-    //~| ERROR associated type `Item` not found for `T`
 {
     data: T
 }

src/test/ui/cycle-projection-based-on-where-clause.stderr

@@ -11,13 +11,6 @@ note: cycle used when processing `A`
 LL |           T : Add<T::Item>
    |                   ^^^^^^^
 
-error[E0220]: associated type `Item` not found for `T`
-  --> $DIR/cycle-projection-based-on-where-clause.rs:17:19
-   |
-LL |           T : Add<T::Item>
-   |                   ^^^^^^^ associated type `Item` not found
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0220, E0391.
-For more information about an error, try `rustc --explain E0220`.
+For more information about this error, try `rustc --explain E0391`.

src/test/ui/issues/issue-20772.rs

@@ -1,6 +1,5 @@
 trait T : Iterator<Item=Self::Item>
 //~^ ERROR cycle detected
-//~| ERROR associated type `Item` not found for `Self`
 {}
 
 fn main() {}

src/test/ui/issues/issue-20772.stderr

@@ -3,7 +3,6 @@ error[E0391]: cycle detected when computing the supertraits of `T`
    |
 LL | / trait T : Iterator<Item=Self::Item>
 LL | |
-LL | |
 LL | | {}
    | |__^
    |
@@ -13,17 +12,9 @@ note: cycle used when collecting item types in top-level module
    |
 LL | / trait T : Iterator<Item=Self::Item>
 LL | |
-LL | |
 LL | | {}
    | |__^
 
-error[E0220]: associated type `Item` not found for `Self`
-  --> $DIR/issue-20772.rs:1:25
-   |
-LL | trait T : Iterator<Item=Self::Item>
-   |                         ^^^^^^^^^^ associated type `Item` not found
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0220, E0391.
-For more information about an error, try `rustc --explain E0220`.
+For more information about this error, try `rustc --explain E0391`.

src/test/ui/issues/issue-21177.rs

@@ -5,6 +5,5 @@ trait Trait {
 
 fn foo<T: Trait<A = T::B>>() { }
 //~^ ERROR cycle detected
-//~| ERROR associated type `B` not found for `T`
 
 fn main() { }

src/test/ui/issues/issue-21177.stderr

@@ -11,13 +11,6 @@ note: cycle used when processing `foo`
 LL | fn foo<T: Trait<A = T::B>>() { }
    |                     ^^^^
 
-error[E0220]: associated type `B` not found for `T`
-  --> $DIR/issue-21177.rs:6:21
-   |
-LL | fn foo<T: Trait<A = T::B>>() { }
-   |                     ^^^^ associated type `B` not found
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0220, E0391.
-For more information about an error, try `rustc --explain E0220`.
+For more information about this error, try `rustc --explain E0391`.

src/test/ui/issues/issue-23302-3.rs

@@ -1,5 +1,4 @@
 const A: i32 = B; //~ ERROR cycle detected
-//~^ ERROR cycle detected
 
 const B: i32 = A;
 

src/test/ui/issues/issue-23302-3.stderr

@@ -10,36 +10,18 @@ note: ...which requires checking which parts of `A` are promotable to static...
 LL | const A: i32 = B;
    |                ^
 note: ...which requires const checking if rvalue is promotable to static `B`...
-  --> $DIR/issue-23302-3.rs:4:1
+  --> $DIR/issue-23302-3.rs:3:1
    |
 LL | const B: i32 = A;
    | ^^^^^^^^^^^^^^^^^
 note: ...which requires checking which parts of `B` are promotable to static...
-  --> $DIR/issue-23302-3.rs:4:16
+  --> $DIR/issue-23302-3.rs:3:16
    |
 LL | const B: i32 = A;
    |                ^
    = note: ...which again requires const checking if rvalue is promotable to static `A`, completing the cycle
    = note: cycle used when running analysis passes on this crate
 
-error[E0391]: cycle detected when processing `A`
-  --> $DIR/issue-23302-3.rs:1:16
-   |
-LL | const A: i32 = B;
-   |                ^
-   |
-note: ...which requires processing `B`...
-  --> $DIR/issue-23302-3.rs:4:16
-   |
-LL | const B: i32 = A;
-   |                ^
-   = note: ...which again requires processing `A`, completing the cycle
-note: cycle used when processing `A`
-  --> $DIR/issue-23302-3.rs:1:1
-   |
-LL | const A: i32 = B;
-   | ^^^^^^^^^^^^^^^^^
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0391`.