From 3cd5ad5cd7d85fc36c3696e3022bef5c5af088d2 Mon Sep 17 00:00:00 2001
From: jackh726 <jack.huey@umassmed.edu>
Date: Thu, 15 Jul 2021 10:03:39 -0400
Subject: Better diagnostics when mismatched types due to implict static
 lifetime

---
 .../src/traits/error_reporting/suggestions.rs                     | 3 ++-
 compiler/rustc_trait_selection/src/traits/select/mod.rs           | 8 +++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

(limited to 'compiler/rustc_trait_selection')

diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index adeb1d58d1e..50a18ce0ebf 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -1903,7 +1903,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             | ObligationCauseCode::UnifyReceiver(..)
             | ObligationCauseCode::OpaqueType
             | ObligationCauseCode::MiscObligation
-            | ObligationCauseCode::WellFormed(..) => {}
+            | ObligationCauseCode::WellFormed(..)
+            | ObligationCauseCode::MatchImpl(..) => {}
             ObligationCauseCode::SliceOrArrayElem => {
                 err.note("slice and array elements must have `Sized` type");
             }
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 564c63ef30c..1bdc8b34cf6 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -1903,9 +1903,15 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
         debug!(?impl_trait_ref, ?placeholder_obligation_trait_ref);
 
+        let cause = ObligationCause::new(
+            obligation.cause.span,
+            obligation.cause.body_id,
+            ObligationCauseCode::MatchImpl(Lrc::new(obligation.cause.code.clone()), impl_def_id),
+        );
+
         let InferOk { obligations, .. } = self
             .infcx
-            .at(&obligation.cause, obligation.param_env)
+            .at(&cause, obligation.param_env)
             .eq(placeholder_obligation_trait_ref, impl_trait_ref)
             .map_err(|e| debug!("match_impl: failed eq_trait_refs due to `{}`", e))?;
         nested_obligations.extend(obligations);
-- 
cgit 1.4.1-3-g733a5