rename reported_signature_mismatch to reflect its use

compiler/rustc_infer/src/infer/at.rs

@@ -84,7 +84,7 @@ pub fn fork_with_intercrate(&self, intercrate: bool) -> Self {
             selection_cache: self.selection_cache.clone(),
             evaluation_cache: self.evaluation_cache.clone(),
             reported_trait_errors: self.reported_trait_errors.clone(),
-            reported_closure_mismatch: self.reported_closure_mismatch.clone(),
+            reported_signature_mismatch: self.reported_signature_mismatch.clone(),
             tainted_by_errors: self.tainted_by_errors.clone(),
             err_count_on_creation: self.err_count_on_creation,
             universe: self.universe.clone(),

compiler/rustc_infer/src/infer/mod.rs

@@ -278,7 +278,7 @@ pub struct InferCtxt<'tcx> {
     /// avoid reporting the same error twice.
     pub reported_trait_errors: RefCell<FxIndexMap<Span, Vec<ty::Predicate<'tcx>>>>,
 
-    pub reported_closure_mismatch: RefCell<FxHashSet<(Span, Option<Span>)>>,
+    pub reported_signature_mismatch: RefCell<FxHashSet<(Span, Option<Span>)>>,
 
     /// When an error occurs, we want to avoid reporting "derived"
     /// errors that are due to this original failure. Normally, we
@@ -702,7 +702,7 @@ pub fn build(&mut self) -> InferCtxt<'tcx> {
             selection_cache: Default::default(),
             evaluation_cache: Default::default(),
             reported_trait_errors: Default::default(),
-            reported_closure_mismatch: Default::default(),
+            reported_signature_mismatch: Default::default(),
             tainted_by_errors: Cell::new(None),
             err_count_on_creation: tcx.dcx().err_count(),
             universe: Cell::new(ty::UniverseIndex::ROOT),

compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs

@@ -3459,14 +3459,12 @@ fn report_type_parameter_mismatch_error(
         let found_node = found_did.and_then(|did| self.tcx.hir().get_if_local(did));
         let found_span = found_did.and_then(|did| self.tcx.hir().span_if_local(did));
 
-        if self.reported_closure_mismatch.borrow().contains(&(span, found_span)) {
+        if !self.reported_signature_mismatch.borrow_mut().insert((span, found_span)) {
             // We check closures twice, with obligations flowing in different directions,
             // but we want to complain about them only once.
             return None;
         }
 
-        self.reported_closure_mismatch.borrow_mut().insert((span, found_span));
-
         let mut not_tupled = false;
 
         let found = match found_trait_ref.skip_binder().args.type_at(1).kind() {