Auto merge of #124952 - compiler-errors:no-error, r=lcnr

Rename some `FulfillmentErrorCode`/`ObligationCauseCode` variants to be less redundant

1. Rename some `FulfillmentErrorCode` variants.
2. Always use `ObligationCauseCode::` to prefix a code, rather than using a glob import and naming them through `traits::`.
3. Rename some `ObligationCauseCode` variants -- I wasn't particularly thorough with thinking of a new names for these, so could workshop them if necessary.
4. Misc stuff from renaming.

r? lcnr

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1344,7 +1344,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                     Applicability::MaybeIncorrect,
                                 );
                                 for error in errors {
-                                    if let FulfillmentErrorCode::SelectionError(
+                                    if let FulfillmentErrorCode::Select(
                                         SelectionError::Unimplemented,
                                     ) = error.code
                                         && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1283,7 +1283,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                 }
                                 // The type doesn't implement Clone because of unmet obligations.
                                 for error in errors {
-                                    if let traits::FulfillmentErrorCode::SelectionError(
+                                    if let traits::FulfillmentErrorCode::Select(
                                         traits::SelectionError::Unimplemented,
                                     ) = error.code
                                         && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -2059,15 +2059,15 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     // We currently do not store the `DefId` in the `ConstraintCategory`
                     // for performances reasons. The error reporting code used by NLL only
                     // uses the span, so this doesn't cause any problems at the moment.
-                    Some(ObligationCauseCode::BindingObligation(
+                    Some(ObligationCauseCode::SpannedWhereClause(
                         CRATE_DEF_ID.to_def_id(),
                         predicate_span,
                     ))
                 } else {
                     None
                 }
             })
-            .unwrap_or_else(|| ObligationCauseCode::MiscObligation);
+            .unwrap_or_else(|| ObligationCauseCode::Misc);
 
         // Classify each of the constraints along the path.
         let mut categorized_path: Vec<BlameConstraint<'tcx>> = path

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -738,7 +738,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 let cause = ObligationCause::new(
                     terminator.source_info.span,
                     self.body.source.def_id().expect_local(),
-                    ObligationCauseCode::ItemObligation(callee),
+                    ObligationCauseCode::WhereClause(callee),
                 );
                 let normalized_predicates = ocx.normalize(&cause, param_env, predicates);
                 ocx.register_obligations(traits::predicates_for_generics(

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -175,7 +175,7 @@ fn compare_method_predicate_entailment<'tcx>(
     let cause = ObligationCause::new(
         impl_m_span,
         impl_m_def_id,
-        ObligationCauseCode::CompareImplItemObligation {
+        ObligationCauseCode::CompareImplItem {
             impl_item_def_id: impl_m_def_id,
             trait_item_def_id: trait_m.def_id,
             kind: impl_m.kind,
@@ -236,7 +236,7 @@ fn compare_method_predicate_entailment<'tcx>(
         let cause = ObligationCause::new(
             span,
             impl_m_def_id,
-            ObligationCauseCode::CompareImplItemObligation {
+            ObligationCauseCode::CompareImplItem {
                 impl_item_def_id: impl_m_def_id,
                 trait_item_def_id: trait_m.def_id,
                 kind: impl_m.kind,
@@ -464,7 +464,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
     let cause = ObligationCause::new(
         return_span,
         impl_m_def_id,
-        ObligationCauseCode::CompareImplItemObligation {
+        ObligationCauseCode::CompareImplItem {
             impl_item_def_id: impl_m_def_id,
             trait_item_def_id: trait_m.def_id,
             kind: impl_m.kind,
@@ -819,7 +819,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ImplTraitInTraitCollector<'_, 'tcx> {
                     ObligationCause::new(
                         self.span,
                         self.body_id,
-                        ObligationCauseCode::BindingObligation(proj.def_id, pred_span),
+                        ObligationCauseCode::SpannedWhereClause(proj.def_id, pred_span),
                     ),
                     self.param_env,
                     pred,
@@ -1752,7 +1752,7 @@ fn compare_const_predicate_entailment<'tcx>(
     let impl_ty = tcx.type_of(impl_ct_def_id).instantiate_identity();
 
     let trait_ty = tcx.type_of(trait_ct.def_id).instantiate(tcx, trait_to_impl_args);
-    let code = ObligationCauseCode::CompareImplItemObligation {
+    let code = ObligationCauseCode::CompareImplItem {
         impl_item_def_id: impl_ct_def_id,
         trait_item_def_id: trait_ct.def_id,
         kind: impl_ct.kind,
@@ -1924,7 +1924,7 @@ fn compare_type_predicate_entailment<'tcx>(
         let cause = ObligationCause::new(
             span,
             impl_ty_def_id,
-            ObligationCauseCode::CompareImplItemObligation {
+            ObligationCauseCode::CompareImplItem {
                 impl_item_def_id: impl_ty.def_id.expect_local(),
                 trait_item_def_id: trait_ty.def_id,
                 kind: impl_ty.kind,
@@ -2012,9 +2012,9 @@ pub(super) fn check_type_bounds<'tcx>(
     );
     let mk_cause = |span: Span| {
         let code = if span.is_dummy() {
-            traits::ItemObligation(trait_ty.def_id)
+            ObligationCauseCode::WhereClause(trait_ty.def_id)
         } else {
-            traits::BindingObligation(trait_ty.def_id, span)
+            ObligationCauseCode::SpannedWhereClause(trait_ty.def_id, span)
         };
         ObligationCause::new(impl_ty_span, impl_ty_def_id, code)
     };
@@ -2251,7 +2251,8 @@ fn try_report_async_mismatch<'tcx>(
     };
 
     for error in errors {
-        if let traits::BindingObligation(def_id, _) = *error.root_obligation.cause.code()
+        if let ObligationCauseCode::SpannedWhereClause(def_id, _) =
+            *error.root_obligation.cause.code()
             && def_id == async_future_def_id
             && let Some(proj) = error.root_obligation.predicate.to_opt_poly_projection_pred()
             && let Some(proj) = proj.no_bound_vars()

compiler/rustc_hir_analysis/src/check/dropck.rs

@@ -5,6 +5,7 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{codes::*, struct_span_code_err, ErrorGuaranteed};
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
+use rustc_infer::traits::ObligationCauseCode;
 use rustc_middle::ty::util::CheckRegions;
 use rustc_middle::ty::GenericArgsRef;
 use rustc_middle::ty::{self, TyCtxt};
@@ -139,7 +140,7 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
     for (pred, span) in tcx.predicates_of(drop_impl_def_id).instantiate_identity(tcx) {
         let normalize_cause = traits::ObligationCause::misc(span, adt_def_id);
         let pred = ocx.normalize(&normalize_cause, param_env, pred);
-        let cause = traits::ObligationCause::new(span, adt_def_id, traits::DropImpl);
+        let cause = traits::ObligationCause::new(span, adt_def_id, ObligationCauseCode::DropImpl);
         ocx.register_obligation(traits::Obligation::new(tcx, cause, param_env, pred));
     }
 

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1136,7 +1136,7 @@ fn check_type_defn<'tcx>(
                     traits::ObligationCause::new(
                         hir_ty.span,
                         wfcx.body_def_id,
-                        traits::FieldSized {
+                        ObligationCauseCode::FieldSized {
                             adt_kind: match &item.kind {
                                 ItemKind::Struct(..) => AdtKind::Struct,
                                 ItemKind::Union(..) => AdtKind::Union,
@@ -1161,7 +1161,7 @@ fn check_type_defn<'tcx>(
                 let cause = traits::ObligationCause::new(
                     tcx.def_span(discr_def_id),
                     wfcx.body_def_id,
-                    traits::MiscObligation,
+                    ObligationCauseCode::Misc,
                 );
                 wfcx.register_obligation(traits::Obligation::new(
                     tcx,
@@ -1278,7 +1278,11 @@ fn check_item_type(
         wfcx.register_wf_obligation(ty_span, Some(WellFormedLoc::Ty(item_id)), item_ty.into());
         if forbid_unsized {
             wfcx.register_bound(
-                traits::ObligationCause::new(ty_span, wfcx.body_def_id, traits::WellFormed(None)),
+                traits::ObligationCause::new(
+                    ty_span,
+                    wfcx.body_def_id,
+                    ObligationCauseCode::WellFormed(None),
+                ),
                 wfcx.param_env,
                 item_ty,
                 tcx.require_lang_item(LangItem::Sized, None),
@@ -1293,7 +1297,11 @@ fn check_item_type(
 
         if should_check_for_sync {
             wfcx.register_bound(
-                traits::ObligationCause::new(ty_span, wfcx.body_def_id, traits::SharedStatic),
+                traits::ObligationCause::new(
+                    ty_span,
+                    wfcx.body_def_id,
+                    ObligationCauseCode::SharedStatic,
+                ),
                 wfcx.param_env,
                 item_ty,
                 tcx.require_lang_item(LangItem::Sync, Some(ty_span)),
@@ -1542,7 +1550,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
             let cause = traits::ObligationCause::new(
                 sp,
                 wfcx.body_def_id,
-                traits::ItemObligation(def_id.to_def_id()),
+                ObligationCauseCode::WhereClause(def_id.to_def_id()),
             );
             traits::Obligation::new(tcx, cause, wfcx.param_env, pred)
         });
@@ -1982,7 +1990,11 @@ impl<'tcx> WfCheckingCtxt<'_, 'tcx> {
 
                 let obligation = traits::Obligation::new(
                     tcx,
-                    traits::ObligationCause::new(span, self.body_def_id, traits::TrivialBound),
+                    traits::ObligationCause::new(
+                        span,
+                        self.body_def_id,
+                        ObligationCauseCode::TrivialBound,
+                    ),
                     empty_env,
                     pred,
                 );

compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs

@@ -212,7 +212,7 @@ fn get_impl_args(
             traits::ObligationCause::new(
                 impl1_span,
                 impl1_def_id,
-                traits::ObligationCauseCode::BindingObligation(impl2_node.def_id(), span),
+                traits::ObligationCauseCode::SpannedWhereClause(impl2_node.def_id(), span),
             )
         },
     );

compiler/rustc_hir_typeck/src/callee.rs

@@ -9,6 +9,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{self, CtorKind, Namespace, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir_analysis::autoderef::Autoderef;
+use rustc_infer::traits::ObligationCauseCode;
 use rustc_infer::{
     infer,
     traits::{self, Obligation, ObligationCause},
@@ -117,7 +118,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
 
         // we must check that return type of called functions is WF:
-        self.register_wf_obligation(output.into(), call_expr.span, traits::WellFormed(None));
+        self.register_wf_obligation(
+            output.into(),
+            call_expr.span,
+            ObligationCauseCode::WellFormed(None),
+        );
 
         output
     }
@@ -524,9 +529,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 self.register_bound(
                     ty,
                     self.tcx.require_lang_item(hir::LangItem::Tuple, Some(sp)),
-                    traits::ObligationCause::new(sp, self.body_id, traits::RustCall),
+                    traits::ObligationCause::new(sp, self.body_id, ObligationCauseCode::RustCall),
                 );
-                self.require_type_is_sized(ty, sp, traits::RustCall);
+                self.require_type_is_sized(ty, sp, ObligationCauseCode::RustCall);
             } else {
                 self.dcx().emit_err(errors::RustCallIncorrectArgs { span: sp });
             }

compiler/rustc_hir_typeck/src/check.rs

@@ -14,7 +14,6 @@ use rustc_middle::ty::{self, Binder, Ty, TyCtxt};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::symbol::sym;
 use rustc_target::spec::abi::Abi;
-use rustc_trait_selection::traits;
 use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode};
 
 /// Helper used for fns and closures. Does the grungy work of checking a function
@@ -76,7 +75,7 @@ pub(super) fn check_fn<'a, 'tcx>(
             fcx.register_wf_obligation(
                 param_ty.into(),
                 param.span,
-                traits::WellFormed(Some(WellFormedLoc::Param {
+                ObligationCauseCode::WellFormed(Some(WellFormedLoc::Param {
                     function: fn_def_id,
                     param_idx: idx,
                 })),
@@ -101,7 +100,7 @@ pub(super) fn check_fn<'a, 'tcx>(
                 param.pat.span,
                 // ty.span == binding_span iff this is a closure parameter with no type ascription,
                 // or if it's an implicit `self` parameter
-                traits::SizedArgumentType(
+                ObligationCauseCode::SizedArgumentType(
                     if ty_span == Some(param.span) && tcx.is_closure_like(fn_def_id.into()) {
                         None
                     } else {
@@ -121,10 +120,18 @@ pub(super) fn check_fn<'a, 'tcx>(
         hir::FnRetTy::Return(ty) => ty.span,
     };
 
-    fcx.require_type_is_sized(declared_ret_ty, return_or_body_span, traits::SizedReturnType);
+    fcx.require_type_is_sized(
+        declared_ret_ty,
+        return_or_body_span,
+        ObligationCauseCode::SizedReturnType,
+    );
     // We checked the root's signature during wfcheck, but not the child.
     if fcx.tcx.is_typeck_child(fn_def_id.to_def_id()) {
-        fcx.require_type_is_sized(declared_ret_ty, return_or_body_span, traits::WellFormed(None));
+        fcx.require_type_is_sized(
+            declared_ret_ty,
+            return_or_body_span,
+            ObligationCauseCode::WellFormed(None),
+        );
     }
 
     fcx.is_whole_body.set(true);

compiler/rustc_hir_typeck/src/closure.rs

@@ -8,6 +8,7 @@ use rustc_hir::lang_items::LangItem;
 use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
 use rustc_infer::infer::{BoundRegionConversionTime, DefineOpaqueTypes};
 use rustc_infer::infer::{InferOk, InferResult};
+use rustc_infer::traits::ObligationCauseCode;
 use rustc_macros::{TypeFoldable, TypeVisitable};
 use rustc_middle::ty::visit::{TypeVisitable, TypeVisitableExt};
 use rustc_middle::ty::GenericArgs;
@@ -119,7 +120,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)
                     | hir::CoroutineKind::Coroutine(_) => {
                         let yield_ty = self.next_ty_var(expr_span);
-                        self.require_type_is_sized(yield_ty, expr_span, traits::SizedYieldType);
+                        self.require_type_is_sized(
+                            yield_ty,
+                            expr_span,
+                            ObligationCauseCode::SizedYieldType,
+                        );
                         yield_ty
                     }
                     // HACK(-Ztrait-solver=next): In the *old* trait solver, we must eagerly
@@ -128,7 +133,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // not a problem.
                     hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _) => {
                         let yield_ty = self.next_ty_var(expr_span);
-                        self.require_type_is_sized(yield_ty, expr_span, traits::SizedYieldType);
+                        self.require_type_is_sized(
+                            yield_ty,
+                            expr_span,
+                            ObligationCauseCode::SizedYieldType,
+                        );
 
                         Ty::new_adt(
                             tcx,