`#[must_use]` for fns returning a list of errors

2 files changed, 3 insertions, 0 deletions

diff --git a/compiler/rustc_infer/src/infer/outlives/mod.rs b/compiler/rustc_infer/src/infer/outlives/mod.rs
index 21907c4b423..9a9a1696b00 100644
--- a/compiler/rustc_infer/src/infer/outlives/mod.rs
+++ b/compiler/rustc_infer/src/infer/outlives/mod.rs
@@ -75,6 +75,7 @@ impl<'tcx> InferCtxt<'tcx> {
     /// result. After this, no more unification operations should be
     /// done -- or the compiler will panic -- but it is legal to use
     /// `resolve_vars_if_possible` as well as `fully_resolve`.
+    #[must_use]
     pub fn resolve_regions(
         &self,
         outlives_env: &OutlivesEnvironment<'tcx>,
diff --git a/compiler/rustc_infer/src/traits/engine.rs b/compiler/rustc_infer/src/traits/engine.rs
index f75344f20b6..a188bb23882 100644
--- a/compiler/rustc_infer/src/traits/engine.rs
+++ b/compiler/rustc_infer/src/traits/engine.rs
@@ -36,6 +36,7 @@ pub trait TraitEngine<'tcx>: 'tcx {
         obligation: PredicateObligation<'tcx>,
     );
 
+    #[must_use]
     fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
 
     fn collect_remaining_errors(&mut self) -> Vec<FulfillmentError<'tcx>>;
@@ -58,6 +59,7 @@ pub trait TraitEngineExt<'tcx> {
         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
     );
 
+    #[must_use]
     fn select_all_or_error(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
 }