Slightly improve mismatched GAT where clause error

[rust.git] / compiler / rustc_typeck / src / check / compare_method.rs

diff --git a/compiler/rustc_typeck/src/check/compare_method.rs b/compiler/rustc_typeck/src/check/compare_method.rs
index 1a9354f5d20c54c287c46d26fead0216daa752e7..91364ac35cb111163259da382eccde2392a8ee2b 100644 (file)
--- a/compiler/rustc_typeck/src/check/compare_method.rs
+++ b/compiler/rustc_typeck/src/check/compare_method.rs
@@ -1212,15 +1212,6 @@ fn compare_type_predicate_entailment<'tcx>(
     // `ObligationCause` (and the `FnCtxt`). This is what
     // `regionck_item` expects.
     let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local());
-    let cause = ObligationCause::new(
-        impl_ty_span,
-        impl_ty_hir_id,
-        ObligationCauseCode::CompareImplTypeObligation {
-            impl_item_def_id: impl_ty.def_id.expect_local(),
-            trait_item_def_id: trait_ty.def_id,
-        },
-    );
-
     debug!("compare_type_predicate_entailment: trait_to_impl_substs={:?}", trait_to_impl_substs);
 
     // The predicates declared by the impl definition, the trait and the
@@ -1239,7 +1230,7 @@ fn compare_type_predicate_entailment<'tcx>(
         Reveal::UserFacing,
         hir::Constness::NotConst,
     );
-    let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause.clone());
+    let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause);
     tcx.infer_ctxt().enter(|infcx| {
         let ocx = ObligationCtxt::new(&infcx);
 
@@ -1247,12 +1238,24 @@ fn compare_type_predicate_entailment<'tcx>(
 
         let mut selcx = traits::SelectionContext::new(&infcx);
 
-        for predicate in impl_ty_own_bounds.predicates {
+        assert_eq!(impl_ty_own_bounds.predicates.len(), impl_ty_own_bounds.spans.len());
+        for (span, predicate) in
+            std::iter::zip(impl_ty_own_bounds.spans, impl_ty_own_bounds.predicates)
+        {
+            let cause = ObligationCause::misc(span, impl_ty_hir_id);
             let traits::Normalized { value: predicate, obligations } =
-                traits::normalize(&mut selcx, param_env, normalize_cause.clone(), predicate);
+                traits::normalize(&mut selcx, param_env, cause, predicate);
 
+            let cause = ObligationCause::new(
+                span,
+                impl_ty_hir_id,
+                ObligationCauseCode::CompareImplTypeObligation {
+                    impl_item_def_id: impl_ty.def_id.expect_local(),
+                    trait_item_def_id: trait_ty.def_id,
+                },
+            );
             ocx.register_obligations(obligations);
-            ocx.register_obligation(traits::Obligation::new(cause.clone(), param_env, predicate));
+            ocx.register_obligation(traits::Obligation::new(cause, param_env, predicate));
         }
 
         // Check that all obligations are satisfied by the implementation's