Point at explicit `'static` obligations on a trait

Given `trait Any: 'static` and a `struct` with a `Box<dyn Any + 'a>` field, point at the `'static` bound in `Any` to explain why `'a: 'static`.

```
error[E0478]: lifetime bound not satisfied
   --> f202.rs:2:12
    |
2   |     value: Box<dyn std::any::Any + 'a>,
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
note: lifetime parameter instantiated with the lifetime `'a` as defined here
   --> f202.rs:1:14
    |
1   | struct Hello<'a> {
    |              ^^
note: but lifetime parameter must outlive the static lifetime
   --> /home/gh-estebank/rust/library/core/src/any.rs:113:16
    |
113 | pub trait Any: 'static {
    |                ^^^^^^^
```

Partially address #33652.

2 files changed, 8 insertions, 4 deletions

diff --git a/compiler/rustc_infer/src/infer/context.rs b/compiler/rustc_infer/src/infer/context.rs
index f35a8162d96..95888beb6b1 100644
--- a/compiler/rustc_infer/src/infer/context.rs
+++ b/compiler/rustc_infer/src/infer/context.rs
@@ -167,7 +167,7 @@ impl<'tcx> InferCtxtLike for InferCtxt<'tcx> {
     }
 
     fn sub_regions(&self, sub: ty::Region<'tcx>, sup: ty::Region<'tcx>) {
-        self.sub_regions(SubregionOrigin::RelateRegionParamBound(DUMMY_SP), sub, sup)
+        self.sub_regions(SubregionOrigin::RelateRegionParamBound(DUMMY_SP, None), sub, sup)
     }
 
     fn register_ty_outlives(&self, ty: Ty<'tcx>, r: ty::Region<'tcx>) {
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index f2fc25a2d2e..5aa7f259685 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -390,7 +390,7 @@ pub enum SubregionOrigin<'tcx> {
 
     /// The given region parameter was instantiated with a region
     /// that must outlive some other region.
-    RelateRegionParamBound(Span),
+    RelateRegionParamBound(Span, Option<Ty<'tcx>>),
 
     /// Creating a pointer `b` to contents of another reference.
     Reborrow(Span),
@@ -859,7 +859,7 @@ impl<'tcx> InferCtxt<'tcx> {
     ) {
         self.enter_forall(predicate, |ty::OutlivesPredicate(r_a, r_b)| {
             let origin = SubregionOrigin::from_obligation_cause(cause, || {
-                RelateRegionParamBound(cause.span)
+                RelateRegionParamBound(cause.span, None)
             });
             self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b`
         })
@@ -1685,7 +1685,7 @@ impl<'tcx> SubregionOrigin<'tcx> {
             Subtype(ref a) => a.span(),
             RelateObjectBound(a) => a,
             RelateParamBound(a, ..) => a,
-            RelateRegionParamBound(a) => a,
+            RelateRegionParamBound(a, _) => a,
             Reborrow(a) => a,
             ReferenceOutlivesReferent(_, a) => a,
             CompareImplItemObligation { span, .. } => span,
@@ -1726,6 +1726,10 @@ impl<'tcx> SubregionOrigin<'tcx> {
                 SubregionOrigin::AscribeUserTypeProvePredicate(span)
             }
 
+            traits::ObligationCauseCode::ObjectTypeBound(ty, _reg) => {
+                SubregionOrigin::RelateRegionParamBound(cause.span, Some(ty))
+            }
+
             _ => default(),
         }
     }