Rollup merge of #107700 - jyn514:tools-builder, r=Mark-Simulacrum

[rust.git] / compiler / rustc_trait_selection / src / traits / select / mod.rs

diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index b8f5aeee2d593f4386107e3d11b4f9a2144cffa4..0c6b2406bbdafb0cd0e547a405e72cc988e9a494 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -2454,7 +2454,9 @@ fn match_impl(
             .at(&cause, obligation.param_env)
             .define_opaque_types(false)
             .eq(placeholder_obligation_trait_ref, impl_trait_ref)
-            .map_err(|e| debug!("match_impl: failed eq_trait_refs due to `{e}`"))?;
+            .map_err(|e| {
+                debug!("match_impl: failed eq_trait_refs due to `{}`", e.to_string(self.tcx()))
+            })?;
         nested_obligations.extend(obligations);
 
         if !self.is_intercrate()
@@ -2606,11 +2608,12 @@ fn impl_or_trait_obligations(
         assert_eq!(predicates.parent, None);
         let predicates = predicates.instantiate_own(tcx, substs);
         let mut obligations = Vec::with_capacity(predicates.len());
-        for (predicate, span) in predicates {
+        for (index, (predicate, span)) in predicates.into_iter().enumerate() {
             let cause = cause.clone().derived_cause(parent_trait_pred, |derived| {
                 ImplDerivedObligation(Box::new(ImplDerivedObligationCause {
                     derived,
                     impl_def_id: def_id,
+                    impl_def_predicate_index: Some(index),
                     span,
                 }))
             });