From e1873ba007149e69bb996f7becadc796ed87fc0c Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Sat, 11 Sep 2021 16:41:14 -0700
Subject: [PATCH] cleanup(rustc_trait_selection): remove vestigial code from
 rustc_on_unimplemented

This isn't allowed by the validator, and seems to be unused.
When it was added in ed10a3faae1fd1176b2edf4a61438e0542c103b9,
it was used on `Sized`, and that usage is gone.
---
 compiler/rustc_span/src/symbol.rs                              | 1 -
 .../src/traits/error_reporting/on_unimplemented.rs             | 3 ---
 2 files changed, 4 deletions(-)

diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index c816d060456..41ef0795f25 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -934,7 +934,6 @@ symbols! {
         panic_unwind,
         panicking,
         param_attrs,
-        parent_trait,
         partial_cmp,
         partial_ord,
         passes,
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
index 3a32f1cb903..6128c119b6b 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
@@ -154,9 +154,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 flags.push((sym::from_method, Some(method.to_string())));
             }
         }
-        if let Some((t, _)) = self.get_parent_trait_ref(&obligation.cause.code) {
-            flags.push((sym::parent_trait, Some(t)));
-        }
 
         if let Some(k) = obligation.cause.span.desugaring_kind() {
             flags.push((sym::from_desugaring, None));