Rollup merge of #119897 - compiler-errors:fulfillment-errors, r=lcnr

`OutputTypeParameterMismatch` -> `SignatureMismatch`

I'm probably missing something that made this rename more complicated. What did you end up getting stuck on when renaming this selection error, `@lcnr?`

**also** I renamed the `FulfillmentErrorCode` variants. This is just churn but I wanted to do it forever. I can move it out of this PR if desired.

r? lcnr

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1215,7 +1215,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                     Applicability::MaybeIncorrect,
                                 );
                                 for error in errors {
-                                    if let FulfillmentErrorCode::CodeSelectionError(
+                                    if let FulfillmentErrorCode::SelectionError(
                                         SelectionError::Unimplemented,
                                     ) = error.code
                                         && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1291,7 +1291,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                 }
                                 // The type doesn't implement Clone because of unmet obligations.
                                 for error in errors {
-                                    if let traits::FulfillmentErrorCode::CodeSelectionError(
+                                    if let traits::FulfillmentErrorCode::SelectionError(
                                         traits::SelectionError::Unimplemented,
                                     ) = error.code
                                         && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

@@ -86,7 +86,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // Finally, for ambiguity-related errors, we actually want to look
         // for a parameter that is the source of the inference type left
         // over in this predicate.
-        if let traits::FulfillmentErrorCode::CodeAmbiguity { .. } = error.code {
+        if let traits::FulfillmentErrorCode::Ambiguity { .. } = error.code {
             fallback_param_to_point_at = None;
             self_param_to_point_at = None;
             param_to_point_at =
@@ -361,10 +361,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         error: &traits::FulfillmentError<'tcx>,
         span: Span,
     ) -> bool {
-        if let traits::FulfillmentErrorCode::CodeSelectionError(
-            traits::SelectionError::OutputTypeParameterMismatch(
-                box traits::SelectionOutputTypeParameterMismatch { expected_trait_ref, .. },
-            ),
+        if let traits::FulfillmentErrorCode::SelectionError(
+            traits::SelectionError::SignatureMismatch(box traits::SignatureMismatchData {
+                expected_trait_ref,
+                ..
+            }),
         ) = error.code
             && let ty::Closure(def_id, _) | ty::Coroutine(def_id, ..) =
                 expected_trait_ref.skip_binder().self_ty().kind()

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -1648,7 +1648,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         }
                     }
                     for error in errors {
-                        if let traits::FulfillmentErrorCode::CodeSelectionError(
+                        if let traits::FulfillmentErrorCode::SelectionError(
                             traits::SelectionError::Unimplemented,
                         ) = error.code
                             && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) =

compiler/rustc_infer/src/traits/mod.rs

@@ -17,7 +17,6 @@ use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::{self, Const, ToPredicate, Ty, TyCtxt};
 use rustc_span::Span;
 
-pub use self::FulfillmentErrorCode::*;
 pub use self::ImplSource::*;
 pub use self::SelectionError::*;
 
@@ -129,12 +128,12 @@ pub struct FulfillmentError<'tcx> {
 #[derive(Clone)]
 pub enum FulfillmentErrorCode<'tcx> {
     /// Inherently impossible to fulfill; this trait is implemented if and only if it is already implemented.
-    CodeCycle(Vec<PredicateObligation<'tcx>>),
-    CodeSelectionError(SelectionError<'tcx>),
-    CodeProjectionError(MismatchedProjectionTypes<'tcx>),
-    CodeSubtypeError(ExpectedFound<Ty<'tcx>>, TypeError<'tcx>), // always comes from a SubtypePredicate
-    CodeConstEquateError(ExpectedFound<Const<'tcx>>, TypeError<'tcx>),
-    CodeAmbiguity {
+    Cycle(Vec<PredicateObligation<'tcx>>),
+    SelectionError(SelectionError<'tcx>),
+    ProjectionError(MismatchedProjectionTypes<'tcx>),
+    SubtypeError(ExpectedFound<Ty<'tcx>>, TypeError<'tcx>), // always comes from a SubtypePredicate
+    ConstEquateError(ExpectedFound<Const<'tcx>>, TypeError<'tcx>),
+    Ambiguity {
         /// Overflow reported from the new solver `-Znext-solver`, which will
         /// be reported as an regular error as opposed to a fatal error.
         overflow: bool,

compiler/rustc_infer/src/traits/structural_impls.rs

@@ -37,18 +37,19 @@ impl<'tcx> fmt::Debug for traits::FulfillmentError<'tcx> {
 
 impl<'tcx> fmt::Debug for traits::FulfillmentErrorCode<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        use traits::FulfillmentErrorCode::*;
         match *self {
-            super::CodeSelectionError(ref e) => write!(f, "{e:?}"),
-            super::CodeProjectionError(ref e) => write!(f, "{e:?}"),
-            super::CodeSubtypeError(ref a, ref b) => {
+            SelectionError(ref e) => write!(f, "{e:?}"),
+            ProjectionError(ref e) => write!(f, "{e:?}"),
+            SubtypeError(ref a, ref b) => {
                 write!(f, "CodeSubtypeError({a:?}, {b:?})")
             }
-            super::CodeConstEquateError(ref a, ref b) => {
+            ConstEquateError(ref a, ref b) => {
                 write!(f, "CodeConstEquateError({a:?}, {b:?})")
             }
-            super::CodeAmbiguity { overflow: false } => write!(f, "Ambiguity"),
-            super::CodeAmbiguity { overflow: true } => write!(f, "Overflow"),
-            super::CodeCycle(ref cycle) => write!(f, "Cycle({cycle:?})"),
+            Ambiguity { overflow: false } => write!(f, "Ambiguity"),
+            Ambiguity { overflow: true } => write!(f, "Overflow"),
+            Cycle(ref cycle) => write!(f, "Cycle({cycle:?})"),
         }
     }
 }

compiler/rustc_middle/src/traits/mod.rs

@@ -604,7 +604,7 @@ pub enum SelectionError<'tcx> {
     /// After a closure impl has selected, its "outputs" were evaluated
     /// (which for closures includes the "input" type params) and they
     /// didn't resolve. See `confirm_poly_trait_refs` for more.
-    OutputTypeParameterMismatch(Box<SelectionOutputTypeParameterMismatch<'tcx>>),
+    SignatureMismatch(Box<SignatureMismatchData<'tcx>>),
     /// The trait pointed by `DefId` is not object safe.
     TraitNotObjectSafe(DefId),
     /// A given constant couldn't be evaluated.
@@ -618,7 +618,7 @@ pub enum SelectionError<'tcx> {
 }
 
 #[derive(Clone, Debug, TypeVisitable)]
-pub struct SelectionOutputTypeParameterMismatch<'tcx> {
+pub struct SignatureMismatchData<'tcx> {
     pub found_trait_ref: ty::PolyTraitRef<'tcx>,
     pub expected_trait_ref: ty::PolyTraitRef<'tcx>,
     pub terr: ty::error::TypeError<'tcx>,

compiler/rustc_trait_selection/src/solve/fulfill.rs

@@ -66,10 +66,10 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
                         .0
                     {
                         Ok((_, Certainty::Maybe(MaybeCause::Ambiguity), _)) => {
-                            FulfillmentErrorCode::CodeAmbiguity { overflow: false }
+                            FulfillmentErrorCode::Ambiguity { overflow: false }
                         }
                         Ok((_, Certainty::Maybe(MaybeCause::Overflow), _)) => {
-                            FulfillmentErrorCode::CodeAmbiguity { overflow: true }
+                            FulfillmentErrorCode::Ambiguity { overflow: true }
                         }
                         Ok((_, Certainty::Yes, _)) => {
                             bug!("did not expect successful goal when collecting ambiguity errors")
@@ -108,18 +108,18 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
                                 obligation: obligation.clone(),
                                 code: match goal.predicate.kind().skip_binder() {
                                     ty::PredicateKind::Clause(ty::ClauseKind::Projection(_)) => {
-                                        FulfillmentErrorCode::CodeProjectionError(
+                                        FulfillmentErrorCode::ProjectionError(
                                             // FIXME: This could be a `Sorts` if the term is a type
                                             MismatchedProjectionTypes { err: TypeError::Mismatch },
                                         )
                                     }
                                     ty::PredicateKind::NormalizesTo(..) => {
-                                        FulfillmentErrorCode::CodeProjectionError(
+                                        FulfillmentErrorCode::ProjectionError(
                                             MismatchedProjectionTypes { err: TypeError::Mismatch },
                                         )
                                     }
                                     ty::PredicateKind::AliasRelate(_, _, _) => {
-                                        FulfillmentErrorCode::CodeProjectionError(
+                                        FulfillmentErrorCode::ProjectionError(
                                             MismatchedProjectionTypes { err: TypeError::Mismatch },
                                         )
                                     }
@@ -128,7 +128,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
                                             goal.predicate.kind().rebind((pred.a, pred.b)),
                                         );
                                         let expected_found = ExpectedFound::new(true, a, b);
-                                        FulfillmentErrorCode::CodeSubtypeError(
+                                        FulfillmentErrorCode::SubtypeError(
                                             expected_found,
                                             TypeError::Sorts(expected_found),
                                         )
@@ -138,15 +138,15 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
                                             goal.predicate.kind().rebind((pred.a, pred.b)),
                                         );
                                         let expected_found = ExpectedFound::new(false, a, b);
-                                        FulfillmentErrorCode::CodeSubtypeError(
+                                        FulfillmentErrorCode::SubtypeError(
                                             expected_found,
                                             TypeError::Sorts(expected_found),
                                         )
                                     }
                                     ty::PredicateKind::Clause(_)
                                     | ty::PredicateKind::ObjectSafe(_)
                                     | ty::PredicateKind::Ambiguous => {
-                                        FulfillmentErrorCode::CodeSelectionError(
+                                        FulfillmentErrorCode::SelectionError(
                                             SelectionError::Unimplemented,
                                         )
                                     }

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

@@ -14,8 +14,8 @@ use crate::traits::specialize::to_pretty_impl_header;
 use crate::traits::NormalizeExt;
 use crate::traits::{
     elaborate, FulfillmentError, FulfillmentErrorCode, MismatchedProjectionTypes, Obligation,
-    ObligationCause, ObligationCauseCode, ObligationCtxt, OutputTypeParameterMismatch, Overflow,
-    PredicateObligation, SelectionError, TraitNotObjectSafe,
+    ObligationCause, ObligationCauseCode, ObligationCtxt, Overflow, PredicateObligation,
+    SelectionError, SignatureMismatch, TraitNotObjectSafe,
 };
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_errors::{
@@ -30,7 +30,7 @@ use rustc_hir::{GenericParam, Item, Node};
 use rustc_infer::infer::error_reporting::TypeErrCtxt;
 use rustc_infer::infer::{InferOk, TypeTrace};
 use rustc_middle::traits::select::OverflowError;
-use rustc_middle::traits::{DefiningAnchor, SelectionOutputTypeParameterMismatch};
+use rustc_middle::traits::{DefiningAnchor, SignatureMismatchData};
 use rustc_middle::ty::abstract_const::NotConstEvaluatable;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::fold::{BottomUpFolder, TypeFolder, TypeSuperFoldable};
@@ -785,14 +785,14 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
 
                     ty::PredicateKind::Subtype(predicate) => {
                         // Errors for Subtype predicates show up as
-                        // `FulfillmentErrorCode::CodeSubtypeError`,
+                        // `FulfillmentErrorCode::SubtypeError`,
                         // not selection error.
                         span_bug!(span, "subtype requirement gave wrong error: `{:?}`", predicate)
                     }
 
                     ty::PredicateKind::Coerce(predicate) => {
                         // Errors for Coerce predicates show up as
-                        // `FulfillmentErrorCode::CodeSubtypeError`,
+                        // `FulfillmentErrorCode::SubtypeError`,
                         // not selection error.
                         span_bug!(span, "coerce requirement gave wrong error: `{:?}`", predicate)
                     }
@@ -891,22 +891,22 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 }
             }
 
-            OutputTypeParameterMismatch(box SelectionOutputTypeParameterMismatch {
+            SignatureMismatch(box SignatureMismatchData {
                 found_trait_ref,
                 expected_trait_ref,
                 terr: terr @ TypeError::CyclicTy(_),
-            }) => self.report_type_parameter_mismatch_cyclic_type_error(
+            }) => self.report_cyclic_signature_error(
                 &obligation,
                 found_trait_ref,
                 expected_trait_ref,
                 terr,
             ),
-            OutputTypeParameterMismatch(box SelectionOutputTypeParameterMismatch {
+            SignatureMismatch(box SignatureMismatchData {
                 found_trait_ref,
                 expected_trait_ref,
                 terr: _,
             }) => {
-                match self.report_type_parameter_mismatch_error(
+                match self.report_signature_mismatch_error(
                     &obligation,
                     span,
                     found_trait_ref,
@@ -1492,7 +1492,7 @@ pub(super) trait InferCtxtPrivExt<'tcx> {
         kind: ty::ClosureKind,
     ) -> DiagnosticBuilder<'tcx>;
 
-    fn report_type_parameter_mismatch_cyclic_type_error(
+    fn report_cyclic_signature_error(
         &self,
         obligation: &PredicateObligation<'tcx>,
         found_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
@@ -1506,7 +1506,7 @@ pub(super) trait InferCtxtPrivExt<'tcx> {
         def_id: DefId,
     ) -> DiagnosticBuilder<'tcx>;
 
-    fn report_type_parameter_mismatch_error(
+    fn report_signature_mismatch_error(
         &self,
         obligation: &PredicateObligation<'tcx>,
         span: Span,
@@ -1572,23 +1572,23 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         }
 
         match error.code {
-            FulfillmentErrorCode::CodeSelectionError(ref selection_error) => {
+            FulfillmentErrorCode::SelectionError(ref selection_error) => {
                 self.report_selection_error(
                     error.obligation.clone(),
                     &error.root_obligation,
                     selection_error,
                 );
             }
-            FulfillmentErrorCode::CodeProjectionError(ref e) => {
+            FulfillmentErrorCode::ProjectionError(ref e) => {
                 self.report_projection_error(&error.obligation, e);
             }
-            FulfillmentErrorCode::CodeAmbiguity { overflow: false } => {
+            FulfillmentErrorCode::Ambiguity { overflow: false } => {
                 self.maybe_report_ambiguity(&error.obligation);
             }
-            FulfillmentErrorCode::CodeAmbiguity { overflow: true } => {
+            FulfillmentErrorCode::Ambiguity { overflow: true } => {
                 self.report_overflow_no_abort(error.obligation.clone());
             }
-            FulfillmentErrorCode::CodeSubtypeError(ref expected_found, ref err) => {
+            FulfillmentErrorCode::SubtypeError(ref expected_found, ref err) => {
                 self.report_mismatched_types(
                     &error.obligation.cause,
                     expected_found.expected,
@@ -1597,7 +1597,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 )
                 .emit();
             }
-            FulfillmentErrorCode::CodeConstEquateError(ref expected_found, ref err) => {
+            FulfillmentErrorCode::ConstEquateError(ref expected_found, ref err) => {
                 let mut diag = self.report_mismatched_consts(
                     &error.obligation.cause,
                     expected_found.expected,
@@ -1622,7 +1622,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 }
                 diag.emit();
             }
-            FulfillmentErrorCode::CodeCycle(ref cycle) => {
+            FulfillmentErrorCode::Cycle(ref cycle) => {
                 self.report_overflow_obligation_cycle(cycle);
             }
         }
@@ -3366,7 +3366,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         self.dcx().create_err(err)
     }
 
-    fn report_type_parameter_mismatch_cyclic_type_error(
+    fn report_cyclic_signature_error(
         &self,
         obligation: &PredicateObligation<'tcx>,
         found_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
@@ -3427,7 +3427,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         err
     }
 
-    fn report_type_parameter_mismatch_error(
+    fn report_signature_mismatch_error(
         &self,
         obligation: &PredicateObligation<'tcx>,
         span: Span,
@@ -3446,10 +3446,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         };
 
         let found_did = match *found_trait_ty.kind() {
-            ty::Closure(did, _) | ty::Foreign(did) | ty::FnDef(did, _) | ty::Coroutine(did, ..) => {
-                Some(did)
-            }
-            ty::Adt(def, _) => Some(def.did()),
+            ty::Closure(did, _) | ty::FnDef(did, _) | ty::Coroutine(did, ..) => Some(did),
             _ => None,
         };