2 files changed, 42 insertions, 19 deletions
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index d1f4dbc8d84..92fd4625ee8 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -1254,7 +1254,11 @@ fn check_impl<'tcx>(
                 // therefore don't need to be WF (the trait's `Self: Trait` predicate
                 // won't hold).
                 let trait_ref = tcx.impl_trait_ref(item.owner_id).unwrap();
-                let trait_ref = wfcx.normalize(ast_trait_ref.path.span, None, trait_ref);
+                let trait_ref = wfcx.normalize(
+                    ast_trait_ref.path.span,
+                    Some(WellFormedLoc::Ty(item.hir_id().expect_owner().def_id)),
+                    trait_ref,
+                );
                 let trait_pred = ty::TraitPredicate {
                     trait_ref,
                     constness: match constness {
@@ -1263,7 +1267,7 @@ fn check_impl<'tcx>(
                     },
                     polarity: ty::ImplPolarity::Positive,
                 };
-                let obligations = traits::wf::trait_obligations(
+                let mut obligations = traits::wf::trait_obligations(
                     wfcx.infcx,
                     wfcx.param_env,
                     wfcx.body_id,
@@ -1271,6 +1275,13 @@ fn check_impl<'tcx>(
                     ast_trait_ref.path.span,
                     item,
                 );
+                for obligation in &mut obligations {
+                    if let Some(pred) = obligation.predicate.to_opt_poly_trait_pred()
+                        && pred.self_ty().skip_binder() == trait_ref.self_ty()
+                    {
+                        obligation.cause.span = ast_self_ty.span;
+                    }
+                }
                 debug!(?obligations);
                 wfcx.register_obligations(obligations);
             }
diff --git a/compiler/rustc_hir_analysis/src/hir_wf_check.rs b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
index 4f9d5826583..2dbfc1bc9a2 100644
--- a/compiler/rustc_hir_analysis/src/hir_wf_check.rs
+++ b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
@@ -114,34 +114,46 @@ fn diagnostic_hir_wf_check<'tcx>(
     // Get the starting `hir::Ty` using our `WellFormedLoc`.
     // We will walk 'into' this type to try to find
     // a more precise span for our predicate.
-    let ty = match loc {
+    let tys = match loc {
         WellFormedLoc::Ty(_) => match hir.get(hir_id) {
             hir::Node::ImplItem(item) => match item.kind {
-                hir::ImplItemKind::Type(ty) => Some(ty),
-                hir::ImplItemKind::Const(ty, _) => Some(ty),
+                hir::ImplItemKind::Type(ty) => vec![ty],
+                hir::ImplItemKind::Const(ty, _) => vec![ty],
                 ref item => bug!("Unexpected ImplItem {:?}", item),
             },
             hir::Node::TraitItem(item) => match item.kind {
-                hir::TraitItemKind::Type(_, ty) => ty,
-                hir::TraitItemKind::Const(ty, _) => Some(ty),
+                hir::TraitItemKind::Type(_, ty) => ty.into_iter().collect(),
+                hir::TraitItemKind::Const(ty, _) => vec![ty],
                 ref item => bug!("Unexpected TraitItem {:?}", item),
             },
             hir::Node::Item(item) => match item.kind {
-                hir::ItemKind::Static(ty, _, _) | hir::ItemKind::Const(ty, _) => Some(ty),
-                hir::ItemKind::Impl(ref impl_) => {
-                    assert!(impl_.of_trait.is_none(), "Unexpected trait impl: {:?}", impl_);
-                    Some(impl_.self_ty)
-                }
+                hir::ItemKind::Static(ty, _, _) | hir::ItemKind::Const(ty, _) => vec![ty],
+                hir::ItemKind::Impl(ref impl_) => match &impl_.of_trait {
+                    Some(t) => t
+                        .path
+                        .segments
+                        .last()
+                        .iter()
+                        .flat_map(|seg| seg.args().args)
+                        .filter_map(|arg| {
+                            if let hir::GenericArg::Type(ty) = arg { Some(*ty) } else { None }
+                        })
+                        .chain([impl_.self_ty])
+                        .collect(),
+                    None => {
+                        vec![impl_.self_ty]
+                    }
+                },
                 ref item => bug!("Unexpected item {:?}", item),
             },
-            hir::Node::Field(field) => Some(field.ty),
+            hir::Node::Field(field) => vec![field.ty],
             hir::Node::ForeignItem(ForeignItem {
                 kind: ForeignItemKind::Static(ty, _), ..
-            }) => Some(*ty),
+            }) => vec![*ty],
             hir::Node::GenericParam(hir::GenericParam {
                 kind: hir::GenericParamKind::Type { default: Some(ty), .. },
                 ..
-            }) => Some(*ty),
+            }) => vec![*ty],
             ref node => bug!("Unexpected node {:?}", node),
         },
         WellFormedLoc::Param { function: _, param_idx } => {
@@ -149,16 +161,16 @@ fn diagnostic_hir_wf_check<'tcx>(
             // Get return type
             if param_idx as usize == fn_decl.inputs.len() {
                 match fn_decl.output {
-                    hir::FnRetTy::Return(ty) => Some(ty),
+                    hir::FnRetTy::Return(ty) => vec![ty],
                     // The unit type `()` is always well-formed
-                    hir::FnRetTy::DefaultReturn(_span) => None,
+                    hir::FnRetTy::DefaultReturn(_span) => vec![],
                 }
             } else {
-                Some(&fn_decl.inputs[param_idx as usize])
+                vec![&fn_decl.inputs[param_idx as usize]]
             }
         }
     };
-    if let Some(ty) = ty {
+    for ty in tys {
         visitor.visit_ty(ty);
     }
     visitor.cause