Undo a change that is now unnecessary

Author: oli-obk

compiler/rustc_typeck/src/check/fallback.rs

@@ -218,7 +218,7 @@ impl<'tcx> FnCtxt<'_, 'tcx> {
             .diverging_type_vars
             .borrow()
             .iter()
-            .map(|(&ty, _)| self.infcx.shallow_resolve(ty))
+            .map(|&ty| self.infcx.shallow_resolve(ty))
             .filter_map(|ty| ty.ty_vid())
             .map(|vid| self.infcx.root_var(vid))
             .collect();

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -274,7 +274,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         for a in &adj {
             if let Adjust::NeverToAny = a.kind {
                 if a.target.is_ty_var() {
-                    self.diverging_type_vars.borrow_mut().insert(a.target, expr.span);
+                    self.diverging_type_vars.borrow_mut().insert(a.target);
                     debug!("apply_adjustments: adding `{:?}` as diverging type var", a.target);
                 }
             }

compiler/rustc_typeck/src/check/inherited.rs

@@ -1,7 +1,7 @@
 use super::callee::DeferredCallResolution;
 use super::MaybeInProgressTables;
 
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefIdMap, LocalDefId};
 use rustc_hir::HirIdMap;
@@ -58,7 +58,7 @@ pub struct Inherited<'a, 'tcx> {
     /// Whenever we introduce an adjustment from `!` into a type variable,
     /// we record that type variable here. This is later used to inform
     /// fallback. See the `fallback` module for details.
-    pub(super) diverging_type_vars: RefCell<FxHashMap<Ty<'tcx>, Span>>,
+    pub(super) diverging_type_vars: RefCell<FxHashSet<Ty<'tcx>>>,
 }
 
 impl<'a, 'tcx> Deref for Inherited<'a, 'tcx> {