Add cycle errors to ScrubbedTraitError to remove a couple more calls to new_with_diagnostics

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -54,7 +54,7 @@ impl<
 
 /// Used if you want to have pleasant experience when dealing
 /// with obligations outside of hir or mir typeck.
-pub struct ObligationCtxt<'a, 'tcx, E = ScrubbedTraitError> {
+pub struct ObligationCtxt<'a, 'tcx, E = ScrubbedTraitError<'tcx>> {
     pub infcx: &'a InferCtxt<'tcx>,
     engine: RefCell<Box<dyn TraitEngine<'tcx, E>>>,
 }
@@ -65,21 +65,12 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx, FulfillmentError<'tcx>> {
     }
 }
 
-impl<'a, 'tcx> ObligationCtxt<'a, 'tcx, ScrubbedTraitError> {
+impl<'a, 'tcx> ObligationCtxt<'a, 'tcx, ScrubbedTraitError<'tcx>> {
     pub fn new(infcx: &'a InferCtxt<'tcx>) -> Self {
         Self { infcx, engine: RefCell::new(<dyn TraitEngine<'tcx, _>>::new(infcx)) }
     }
 }
 
-impl<'a, 'tcx, E> ObligationCtxt<'a, 'tcx, E>
-where
-    E: FromSolverError<'tcx, NextSolverError<'tcx>> + FromSolverError<'tcx, OldSolverError<'tcx>>,
-{
-    pub fn new_generic(infcx: &'a InferCtxt<'tcx>) -> Self {
-        Self { infcx, engine: RefCell::new(<dyn TraitEngine<'tcx, _>>::new(infcx)) }
-    }
-}
-
 impl<'a, 'tcx, E> ObligationCtxt<'a, 'tcx, E>
 where
     E: FulfillmentErrorLike<'tcx>,

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -856,16 +856,15 @@ impl<'tcx> FromSolverError<'tcx, OldSolverError<'tcx>> for FulfillmentError<'tcx
     }
 }
 
-impl<'tcx> FromSolverError<'tcx, OldSolverError<'tcx>> for ScrubbedTraitError {
+impl<'tcx> FromSolverError<'tcx, OldSolverError<'tcx>> for ScrubbedTraitError<'tcx> {
     fn from_solver_error(_infcx: &InferCtxt<'tcx>, error: OldSolverError<'tcx>) -> Self {
         match error.error {
             FulfillmentErrorCode::Select(_)
             | FulfillmentErrorCode::Project(_)
             | FulfillmentErrorCode::Subtype(_, _)
             | FulfillmentErrorCode::ConstEquate(_, _) => ScrubbedTraitError::TrueError,
-            FulfillmentErrorCode::Cycle(_) | FulfillmentErrorCode::Ambiguity { overflow: _ } => {
-                ScrubbedTraitError::Ambiguity
-            }
+            FulfillmentErrorCode::Ambiguity { overflow: _ } => ScrubbedTraitError::Ambiguity,
+            FulfillmentErrorCode::Cycle(cycle) => ScrubbedTraitError::Cycle(cycle),
         }
     }
 }

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -77,24 +77,26 @@ pub use rustc_infer::traits::*;
 /// error itself (except for if it's an ambiguity or true error).
 ///
 /// use [`ObligationCtxt::new_with_diagnostics`] to get a [`FulfillmentError`].
-#[derive(Copy, Clone, Debug)]
-pub enum ScrubbedTraitError {
+#[derive(Clone, Debug)]
+pub enum ScrubbedTraitError<'tcx> {
     /// A real error. This goal definitely does not hold.
     TrueError,
     /// An ambiguity. This goal may hold if further inference is done.
     Ambiguity,
+    /// An old-solver-style cycle error, which will fatal.
+    Cycle(Vec<PredicateObligation<'tcx>>),
 }
 
-impl ScrubbedTraitError {
+impl<'tcx> ScrubbedTraitError<'tcx> {
     fn is_true_error(&self) -> bool {
         match self {
             ScrubbedTraitError::TrueError => true,
-            ScrubbedTraitError::Ambiguity => false,
+            ScrubbedTraitError::Ambiguity | ScrubbedTraitError::Cycle(_) => false,
         }
     }
 }
 
-impl<'tcx> FulfillmentErrorLike<'tcx> for ScrubbedTraitError {
+impl<'tcx> FulfillmentErrorLike<'tcx> for ScrubbedTraitError<'tcx> {
     fn is_true_error(&self) -> bool {
         self.is_true_error()
     }

compiler/rustc_trait_selection/src/traits/query/normalize.rs

@@ -76,7 +76,7 @@ impl<'cx, 'tcx> At<'cx, 'tcx> {
         };
 
         if self.infcx.next_trait_solver() {
-            match crate::solve::deeply_normalize_with_skipped_universes::<_, ScrubbedTraitError>(
+            match crate::solve::deeply_normalize_with_skipped_universes::<_, ScrubbedTraitError<'tcx>>(
                 self, value, universes,
             ) {
                 Ok(value) => return Ok(Normalized { value, obligations: vec![] }),

compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs

@@ -267,7 +267,7 @@ pub fn compute_implied_outlives_bounds_compat_inner<'tcx>(
                         ocx.infcx.at(&ObligationCause::dummy(), param_env),
                         ty_a,
                     )
-                    .map_err(|_errs: Vec<ScrubbedTraitError>| NoSolution)?;
+                    .map_err(|_errs: Vec<ScrubbedTraitError<'tcx>>| NoSolution)?;
                 }
                 let mut components = smallvec![];
                 push_outlives_components(tcx, ty_a, &mut components);