Ignore existential type items during collection for now

Author: oli-obk

src/librustc_typeck/collect.rs

@@ -419,7 +419,7 @@ fn convert_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, item_id: ast::NodeId) {
                 convert_variant_ctor(tcx, struct_def.id());
             }
         },
-        hir::ItemExistential(..) |
+        hir::ItemExistential(..) => {}
         hir::ItemTy(..) | hir::ItemStatic(..) | hir::ItemConst(..) | hir::ItemFn(..) => {
             tcx.generics_of(def_id);
             tcx.type_of(def_id);

src/test/ui/impl-trait/auto-trait-leak.rs

@@ -23,9 +23,7 @@ fn main() {
 // return type, which can't depend on the obligation.
 fn cycle1() -> impl Clone {
     //~^ ERROR cycle detected
-    //~| ERROR cycle detected
     send(cycle2().clone());
-    //~^ ERROR `std::rc::Rc<std::string::String>` cannot be sent between threads safely
 
     Rc::new(Cell::new(5))
 }

src/test/ui/impl-trait/auto-trait-leak.stderr

@@ -1,67 +1,29 @@
-error[E0391]: cycle detected when processing `cycle1::{{impl-Trait}}`
-  --> $DIR/auto-trait-leak.rs:24:16
-   |
-LL | fn cycle1() -> impl Clone {
-   |                ^^^^^^^^^^
-   |
-note: ...which requires processing `cycle1`...
+error[E0391]: cycle detected when processing `cycle1`
   --> $DIR/auto-trait-leak.rs:24:1
    |
 LL | fn cycle1() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
 note: ...which requires evaluating trait selection obligation `impl std::clone::Clone: std::marker::Send`...
 note: ...which requires processing `cycle2::{{impl-Trait}}`...
-  --> $DIR/auto-trait-leak.rs:33:16
+  --> $DIR/auto-trait-leak.rs:31:16
    |
 LL | fn cycle2() -> impl Clone {
    |                ^^^^^^^^^^
 note: ...which requires processing `cycle2`...
-  --> $DIR/auto-trait-leak.rs:33:1
+  --> $DIR/auto-trait-leak.rs:31:1
    |
 LL | fn cycle2() -> impl Clone {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
 note: ...which requires evaluating trait selection obligation `impl std::clone::Clone: std::marker::Send`...
-   = note: ...which again requires processing `cycle1::{{impl-Trait}}`, completing the cycle
-
-error[E0391]: cycle detected when processing `cycle1::{{impl-Trait}}`
+note: ...which requires processing `cycle1::{{impl-Trait}}`...
   --> $DIR/auto-trait-leak.rs:24:16
    |
 LL | fn cycle1() -> impl Clone {
    |                ^^^^^^^^^^
-   |
-note: ...which requires processing `cycle1`...
-  --> $DIR/auto-trait-leak.rs:24:1
-   |
-LL | fn cycle1() -> impl Clone {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires evaluating trait selection obligation `impl std::clone::Clone: std::marker::Send`...
-note: ...which requires processing `cycle2::{{impl-Trait}}`...
-  --> $DIR/auto-trait-leak.rs:33:16
-   |
-LL | fn cycle2() -> impl Clone {
-   |                ^^^^^^^^^^
-note: ...which requires processing `cycle2`...
-  --> $DIR/auto-trait-leak.rs:33:1
-   |
-LL | fn cycle2() -> impl Clone {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: ...which again requires processing `cycle1::{{impl-Trait}}`, completing the cycle
-
-error[E0277]: `std::rc::Rc<std::string::String>` cannot be sent between threads safely
-  --> $DIR/auto-trait-leak.rs:27:5
-   |
-LL |     send(cycle2().clone());
-   |     ^^^^ `std::rc::Rc<std::string::String>` cannot be sent between threads safely
-   |
-   = help: within `impl std::clone::Clone`, the trait `std::marker::Send` is not implemented for `std::rc::Rc<std::string::String>`
-   = note: required because it appears within the type `impl std::clone::Clone`
-note: required by `send`
-  --> $DIR/auto-trait-leak.rs:16:1
-   |
-LL | fn send<T: Send>(_: T) {}
-   | ^^^^^^^^^^^^^^^^^^^^^^
+   = note: ...which again requires processing `cycle1`, completing the cycle
+note: cycle used when type-checking all item bodies
 
-error: aborting due to 3 previous errors
+error: aborting due to previous error
 
-Some errors occurred: E0277, E0391.
-For more information about an error, try `rustc --explain E0277`.
+For more information about this error, try `rustc --explain E0391`.