Track all predicates in errors, not just trait obligations

Surface associated type projection bounds that could not be fulfilled in
E0599 errors. Always present the list of unfulfilled trait bounds,
regardless of whether we're pointing at the ADT or trait that didn't
satisfy it.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/librustc/traits/mod.rs b/src/librustc/traits/mod.rs
index b05bd26f048..77c612cf34a 100644
--- a/src/librustc/traits/mod.rs
+++ b/src/librustc/traits/mod.rs
@@ -581,6 +581,20 @@ impl<'tcx, N> Vtable<'tcx, N> {
         }
     }
 
+    pub fn borrow_nested_obligations(&self) -> &[N] {
+        match &self {
+            VtableImpl(i) => &i.nested[..],
+            VtableParam(n) => &n[..],
+            VtableBuiltin(i) => &i.nested[..],
+            VtableAutoImpl(d) => &d.nested[..],
+            VtableClosure(c) => &c.nested[..],
+            VtableGenerator(c) => &c.nested[..],
+            VtableObject(d) => &d.nested[..],
+            VtableFnPointer(d) => &d.nested[..],
+            VtableTraitAlias(d) => &d.nested[..],
+        }
+    }
+
     pub fn map<M, F>(self, f: F) -> Vtable<'tcx, M>
     where
         F: FnMut(N) -> M,