leak_check: remove unused codepath

compiler/rustc_hir_typeck/src/coercion.rs

@@ -824,7 +824,7 @@ fn coerce_from_safe_fn<F, G>(
             // want the coerced type to be the actual supertype of these two,
             // but for now, we want to just error to ensure we don't lock
             // ourselves into a specific behavior with NLL.
-            self.leak_check(false, snapshot)?;
+            self.leak_check(snapshot)?;
 
             result
         })

compiler/rustc_infer/src/infer/higher_ranked/mod.rs

@@ -108,11 +108,7 @@ pub fn instantiate_binder_with_placeholders<T>(&self, binder: ty::Binder<'tcx, T
     /// See [RegionConstraintCollector::leak_check][1].
     ///
     /// [1]: crate::infer::region_constraints::RegionConstraintCollector::leak_check
-    pub fn leak_check(
+    pub fn leak_check(&self, snapshot: &CombinedSnapshot<'tcx>) -> RelateResult<'tcx, ()> {
-        &self,
-        overly_polymorphic: bool,
-        snapshot: &CombinedSnapshot<'tcx>,
-    ) -> RelateResult<'tcx, ()> {
         // If the user gave `-Zno-leak-check`, or we have been
         // configured to skip the leak check, then skip the leak check
         // completely. The leak check is deprecated. Any legitimate
@@ -125,7 +121,6 @@ pub fn leak_check(
 
         self.inner.borrow_mut().unwrap_region_constraints().leak_check(
             self.tcx,
-            overly_polymorphic,
             self.universe(),
             snapshot,
         )

compiler/rustc_infer/src/infer/region_constraints/leak_check.rs

@@ -65,13 +65,12 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
     pub fn leak_check(
         &mut self,
         tcx: TyCtxt<'tcx>,
-        overly_polymorphic: bool,
         max_universe: ty::UniverseIndex,
         snapshot: &CombinedSnapshot<'tcx>,
     ) -> RelateResult<'tcx, ()> {
         debug!(
-            "leak_check(max_universe={:?}, snapshot.universe={:?}, overly_polymorphic={:?})",
+            "leak_check(max_universe={:?}, snapshot.universe={:?})",
-            max_universe, snapshot.universe, overly_polymorphic
+            max_universe, snapshot.universe
         );
 
         assert!(UndoLogs::<super::UndoLog<'_>>::in_snapshot(&self.undo_log));
@@ -84,14 +83,8 @@ pub fn leak_check(
         let mini_graph =
             &MiniGraph::new(tcx, self.undo_log.region_constraints(), &self.storage.data.verifys);
 
-        let mut leak_check = LeakCheck::new(
+        let mut leak_check =
-            tcx,
+            LeakCheck::new(tcx, universe_at_start_of_snapshot, max_universe, mini_graph, self);
-            universe_at_start_of_snapshot,
-            max_universe,
-            overly_polymorphic,
-            mini_graph,
-            self,
-        );
         leak_check.assign_placeholder_values()?;
         leak_check.propagate_scc_value()?;
         Ok(())
@@ -101,8 +94,6 @@ pub fn leak_check(
 struct LeakCheck<'me, 'tcx> {
     tcx: TyCtxt<'tcx>,
     universe_at_start_of_snapshot: ty::UniverseIndex,
-    /// Only used when reporting region errors.
-    overly_polymorphic: bool,
     mini_graph: &'me MiniGraph<'tcx>,
     rcc: &'me RegionConstraintCollector<'me, 'tcx>,
 
@@ -132,7 +123,6 @@ fn new(
         tcx: TyCtxt<'tcx>,
         universe_at_start_of_snapshot: ty::UniverseIndex,
         max_universe: ty::UniverseIndex,
-        overly_polymorphic: bool,
         mini_graph: &'me MiniGraph<'tcx>,
         rcc: &'me RegionConstraintCollector<'me, 'tcx>,
     ) -> Self {
@@ -140,7 +130,6 @@ fn new(
         Self {
             tcx,
             universe_at_start_of_snapshot,
-            overly_polymorphic,
             mini_graph,
             rcc,
             scc_placeholders: IndexVec::from_elem_n(None, mini_graph.sccs.num_sccs()),
@@ -289,11 +278,7 @@ fn error(
         other_region: ty::Region<'tcx>,
     ) -> TypeError<'tcx> {
         debug!("error: placeholder={:?}, other_region={:?}", placeholder, other_region);
-        if self.overly_polymorphic {
+        TypeError::RegionsInsufficientlyPolymorphic(placeholder.bound.kind, other_region)
-            TypeError::RegionsOverlyPolymorphic(placeholder.bound.kind, other_region)
-        } else {
-            TypeError::RegionsInsufficientlyPolymorphic(placeholder.bound.kind, other_region)
-        }
     }
 }
 

compiler/rustc_middle/src/ty/error.rs

@@ -45,7 +45,6 @@ pub enum TypeError<'tcx> {
 
     RegionsDoesNotOutlive(Region<'tcx>, Region<'tcx>),
     RegionsInsufficientlyPolymorphic(BoundRegionKind, Region<'tcx>),
-    RegionsOverlyPolymorphic(BoundRegionKind, Region<'tcx>),
     RegionsPlaceholderMismatch,
 
     Sorts(ExpectedFound<Ty<'tcx>>),
@@ -74,7 +73,6 @@ pub fn involves_regions(self) -> bool {
         match self {
             TypeError::RegionsDoesNotOutlive(_, _)
             | TypeError::RegionsInsufficientlyPolymorphic(_, _)
-            | TypeError::RegionsOverlyPolymorphic(_, _)
             | TypeError::RegionsPlaceholderMismatch => true,
             _ => false,
         }
@@ -98,11 +96,6 @@ fn report_maybe_different(expected: &str, found: &str) -> String {
             }
         }
 
-        let br_string = |br: ty::BoundRegionKind| match br {
-            ty::BrNamed(_, name) => format!(" {}", name),
-            _ => String::new(),
-        };
-
         match self {
             CyclicTy(_) => "cyclic type of infinite size".into(),
             CyclicConst(_) => "encountered a self-referencing constant".into(),
@@ -144,11 +137,6 @@ fn report_maybe_different(expected: &str, found: &str) -> String {
             RegionsInsufficientlyPolymorphic(..) => {
                 "one type is more general than the other".into()
             }
-            RegionsOverlyPolymorphic(br, _) => format!(
-                "expected concrete lifetime, found bound lifetime parameter{}",
-                br_string(br)
-            )
-            .into(),
             RegionsPlaceholderMismatch => "one type is more general than the other".into(),
             ArgumentSorts(values, _) | Sorts(values) => {
                 let expected = values.expected.sort_string(tcx);
@@ -228,7 +216,6 @@ pub fn must_include_note(self) -> bool {
             | FieldMisMatch(..)
             | RegionsDoesNotOutlive(..)
             | RegionsInsufficientlyPolymorphic(..)
-            | RegionsOverlyPolymorphic(..)
             | RegionsPlaceholderMismatch
             | Traits(_)
             | ProjectionMismatched(_)

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -200,7 +200,7 @@ fn overlap_within_probe<'cx, 'tcx>(
 
     // We disable the leak when creating the `snapshot` by using
     // `infcx.probe_maybe_disable_leak_check`.
-    if infcx.leak_check(true, snapshot).is_err() {
+    if infcx.leak_check(snapshot).is_err() {
         debug!("overlap: leak check failed");
         return None;
     }

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -563,7 +563,7 @@ fn evaluation_probe(
         self.infcx.probe(|snapshot| -> Result<EvaluationResult, OverflowError> {
             let result = op(self)?;
 
-            match self.infcx.leak_check(true, snapshot) {
+            match self.infcx.leak_check(snapshot) {
                 Ok(()) => {}
                 Err(_) => return Ok(EvaluatedToErr),
             }