Consolidate obligation cause codes for where clauses

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -2059,10 +2059,7 @@ 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::SpannedWhereClause(
-                        CRATE_DEF_ID.to_def_id(),
-                        predicate_span,
-                    ))
+                    Some(ObligationCauseCode::WhereClause(CRATE_DEF_ID.to_def_id(), predicate_span))
                 } else {
                     None
                 }

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

@@ -11,7 +11,7 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::{self, adjustment::PointerCoercion, Ty, TyCtxt};
 use rustc_middle::ty::{Instance, InstanceDef, TypeVisitableExt};
 use rustc_mir_dataflow::Analysis;
-use rustc_span::{sym, Span, Symbol};
+use rustc_span::{sym, Span, Symbol, DUMMY_SP};
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::{self, ObligationCauseCode, ObligationCtxt};
 use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitor};
@@ -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::WhereClause(callee),
+                    ObligationCauseCode::WhereClause(callee, DUMMY_SP),
                 );
                 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

@@ -819,7 +819,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ImplTraitInTraitCollector<'_, 'tcx> {
                     ObligationCause::new(
                         self.span,
                         self.body_id,
-                        ObligationCauseCode::SpannedWhereClause(proj.def_id, pred_span),
+                        ObligationCauseCode::WhereClause(proj.def_id, pred_span),
                     ),
                     self.param_env,
                     pred,
@@ -2011,11 +2011,7 @@ pub(super) fn check_type_bounds<'tcx>(
         },
     );
     let mk_cause = |span: Span| {
-        let code = if span.is_dummy() {
-            ObligationCauseCode::WhereClause(trait_ty.def_id)
-        } else {
-            ObligationCauseCode::SpannedWhereClause(trait_ty.def_id, span)
-        };
+        let code = ObligationCauseCode::WhereClause(trait_ty.def_id, span);
         ObligationCause::new(impl_ty_span, impl_ty_def_id, code)
     };
 
@@ -2251,8 +2247,7 @@ fn try_report_async_mismatch<'tcx>(
     };
 
     for error in errors {
-        if let ObligationCauseCode::SpannedWhereClause(def_id, _) =
-            *error.root_obligation.cause.code()
+        if let ObligationCauseCode::WhereClause(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/wfcheck.rs

@@ -1550,7 +1550,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
             let cause = traits::ObligationCause::new(
                 sp,
                 wfcx.body_def_id,
-                ObligationCauseCode::WhereClause(def_id.to_def_id()),
+                ObligationCauseCode::WhereClause(def_id.to_def_id(), DUMMY_SP),
             );
             traits::Obligation::new(tcx, cause, wfcx.param_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::SpannedWhereClause(impl2_node.def_id(), span),
+                traits::ObligationCauseCode::WhereClause(impl2_node.def_id(), span),
             )
         },
     );

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -1409,11 +1409,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         hir_id: HirId,
     ) {
         self.add_required_obligations_with_code(span, def_id, args, |idx, span| {
-            if span.is_dummy() {
-                ObligationCauseCode::WhereClauseInExpr(def_id, hir_id, idx)
-            } else {
-                ObligationCauseCode::SpannedWhereClauseInExpr(def_id, span, hir_id, idx)
-            }
+            ObligationCauseCode::WhereClauseInExpr(def_id, span, hir_id, idx)
         })
     }
 

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

@@ -14,8 +14,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         error: &mut traits::FulfillmentError<'tcx>,
     ) -> bool {
-        let (ObligationCauseCode::WhereClauseInExpr(def_id, hir_id, idx)
-        | ObligationCauseCode::SpannedWhereClauseInExpr(def_id, _, hir_id, idx)) =
+        let ObligationCauseCode::WhereClauseInExpr(def_id, _, hir_id, idx) =
             *error.obligation.cause.code().peel_derives()
         else {
             return false;
@@ -512,7 +511,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr: &'tcx hir::Expr<'tcx>,
     ) -> Result<&'tcx hir::Expr<'tcx>, &'tcx hir::Expr<'tcx>> {
         match obligation_cause_code {
-            traits::ObligationCauseCode::SpannedWhereClauseInExpr(_, _, _, _) => {
+            traits::ObligationCauseCode::WhereClauseInExpr(_, _, _, _) => {
                 // This is the "root"; we assume that the `expr` is already pointing here.
                 // Therefore, we return `Ok` so that this `expr` can be refined further.
                 Ok(expr)

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -2013,8 +2013,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         for (span, code) in errors_causecode {
             self.dcx().try_steal_modify_and_emit_err(span, StashKey::MaybeForgetReturn, |err| {
                 if let Some(fn_sig) = self.body_fn_sig()
-                    && let ObligationCauseCode::SpannedWhereClauseInExpr(_, _, binding_hir_id, ..) =
-                        code
+                    && let ObligationCauseCode::WhereClauseInExpr(_, _, binding_hir_id, ..) = code
                     && !fn_sig.output().is_unit()
                 {
                     let mut block_num = 0;
@@ -2103,7 +2102,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         //
         // This is because due to normalization, we often register duplicate
         // obligations with misc obligations that are basically impossible to
-        // line back up with a useful SpannedWhereClauseInExpr.
+        // line back up with a useful WhereClauseInExpr.
         for error in not_adjusted {
             for (span, predicate, cause) in &remap_cause {
                 if *predicate == error.obligation.predicate

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -564,16 +564,12 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
         // `self.add_required_obligations(self.span, def_id, &all_args);`
         for obligation in traits::predicates_for_generics(
             |idx, span| {
-                let code = if span.is_dummy() {
-                    ObligationCauseCode::WhereClauseInExpr(def_id, self.call_expr.hir_id, idx)
-                } else {
-                    ObligationCauseCode::SpannedWhereClauseInExpr(
-                        def_id,
-                        span,
-                        self.call_expr.hir_id,
-                        idx,
-                    )
-                };
+                let code = ObligationCauseCode::WhereClauseInExpr(
+                    def_id,
+                    span,
+                    self.call_expr.hir_id,
+                    idx,
+                );
                 traits::ObligationCause::new(self.span, self.body_id, code)
             },
             self.param_env,

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1401,20 +1401,12 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                     // Convert the bounds into obligations.
                     ocx.register_obligations(traits::predicates_for_generics(
                         |idx, span| {
-                            let code = if span.is_dummy() {
-                                ObligationCauseCode::WhereClauseInExpr(
-                                    impl_def_id,
-                                    self.scope_expr_id,
-                                    idx,
-                                )
-                            } else {
-                                ObligationCauseCode::SpannedWhereClauseInExpr(
-                                    impl_def_id,
-                                    span,
-                                    self.scope_expr_id,
-                                    idx,
-                                )
-                            };
+                            let code = ObligationCauseCode::WhereClauseInExpr(
+                                impl_def_id,
+                                span,
+                                self.scope_expr_id,
+                                idx,
+                            );
                             ObligationCause::new(self.span, self.body_id, code)
                         },
                         self.param_env,

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -832,9 +832,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         (data.impl_or_alias_def_id, data.span)
                     }
                     Some(
-                        ObligationCauseCode::SpannedWhereClauseInExpr(def_id, span, _, _)
-                        | ObligationCauseCode::SpannedWhereClause(def_id, span),
-                    ) => (*def_id, *span),
+                        ObligationCauseCode::WhereClauseInExpr(def_id, span, _, _)
+                        | ObligationCauseCode::WhereClause(def_id, span),
+                    ) if !span.is_dummy() => (*def_id, *span),
                     _ => continue,
                 };
 

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

@@ -883,9 +883,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 err.help("...or use `match` instead of `let...else`");
             }
             _ => {
-                if let ObligationCauseCode::SpannedWhereClause(_, span)
-                | ObligationCauseCode::SpannedWhereClauseInExpr(_, span, ..) =
+                if let ObligationCauseCode::WhereClause(_, span)
+                | ObligationCauseCode::WhereClauseInExpr(_, span, ..) =
                     cause.code().peel_derives()
+                    && !span.is_dummy()
                     && let TypeError::RegionsPlaceholderMismatch = terr
                 {
                     err.span_note(*span, "the lifetime requirement is introduced here");

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs

@@ -38,11 +38,14 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         let ObligationCauseCode::MatchImpl(parent, impl_def_id) = code else {
             return None;
         };
-        let (ObligationCauseCode::SpannedWhereClause(_, binding_span)
-        | ObligationCauseCode::SpannedWhereClauseInExpr(_, binding_span, ..)) = *parent.code()
+        let (ObligationCauseCode::WhereClause(_, binding_span)
+        | ObligationCauseCode::WhereClauseInExpr(_, binding_span, ..)) = *parent.code()
         else {
             return None;
         };
+        if binding_span.is_dummy() {
+            return None;
+        }
 
         // FIXME: we should point at the lifetime
         let multi_span: MultiSpan = vec![binding_span].into();

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs

@@ -10,7 +10,7 @@ use crate::traits::{ObligationCause, ObligationCauseCode};
 use rustc_data_structures::intern::Interned;
 use rustc_errors::{Diag, IntoDiagArg};
 use rustc_hir::def::Namespace;
-use rustc_hir::def_id::DefId;
+use rustc_hir::def_id::{DefId, CRATE_DEF_ID};
 use rustc_middle::ty::error::ExpectedFound;
 use rustc_middle::ty::print::{FmtPrinter, Print, PrintTraitRefExt as _, RegionHighlightMode};
 use rustc_middle::ty::GenericArgsRef;
@@ -240,8 +240,9 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         let span = cause.span();
 
         let (leading_ellipsis, satisfy_span, where_span, dup_span, def_id) =
-            if let ObligationCauseCode::WhereClause(def_id)
-            | ObligationCauseCode::WhereClauseInExpr(def_id, ..) = *cause.code()
+            if let ObligationCauseCode::WhereClause(def_id, span)
+            | ObligationCauseCode::WhereClauseInExpr(def_id, span, ..) = *cause.code()
+                && def_id != CRATE_DEF_ID.to_def_id()
             {
                 (
                     true,

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs

@@ -214,7 +214,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                 _ => cause.code(),
             }
             && let (
-                &ObligationCauseCode::WhereClause(item_def_id)
+                &ObligationCauseCode::WhereClause(item_def_id, _)
                 | &ObligationCauseCode::WhereClauseInExpr(item_def_id, ..),
                 None,
             ) = (code, override_error_code)

compiler/rustc_infer/src/infer/error_reporting/note.rs

@@ -357,21 +357,22 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             infer::Subtype(box ref trace)
                 if matches!(
                     &trace.cause.code().peel_derives(),
-                    ObligationCauseCode::SpannedWhereClause(..)
-                        | ObligationCauseCode::SpannedWhereClauseInExpr(..)
+                    ObligationCauseCode::WhereClause(..)
+                        | ObligationCauseCode::WhereClauseInExpr(..)
                 ) =>
             {
                 // Hack to get around the borrow checker because trace.cause has an `Rc`.
-                if let ObligationCauseCode::SpannedWhereClause(_, span)
-                | ObligationCauseCode::SpannedWhereClauseInExpr(_, span, ..) =
+                if let ObligationCauseCode::WhereClause(_, span)
+                | ObligationCauseCode::WhereClauseInExpr(_, span, ..) =
                     &trace.cause.code().peel_derives()
+                    && !span.is_dummy()
                 {
                     let span = *span;
                     self.report_concrete_failure(placeholder_origin, sub, sup)
                         .with_span_note(span, "the lifetime requirement is introduced here")
                 } else {
                     unreachable!(
-                        "control flow ensures we have a `BindingObligation` or `SpannedWhereClauseInExpr` here..."
+                        "control flow ensures we have a `BindingObligation` or `WhereClauseInExpr` here..."
                     )
                 }
             }

compiler/rustc_infer/src/infer/outlives/obligations.rs

@@ -103,8 +103,12 @@ impl<'tcx> InferCtxt<'tcx> {
                 cause.span,
                 sup_type,
                 match cause.code().peel_derives() {
-                    ObligationCauseCode::SpannedWhereClause(_, span)
-                    | ObligationCauseCode::SpannedWhereClauseInExpr(_, span, ..) => Some(*span),
+                    ObligationCauseCode::WhereClause(_, span)
+                    | ObligationCauseCode::WhereClauseInExpr(_, span, ..)
+                        if !span.is_dummy() =>
+                    {
+                        Some(*span)
+                    }
                     _ => None,
                 },
             )

compiler/rustc_middle/src/traits/mod.rs

@@ -247,22 +247,15 @@ pub enum ObligationCauseCode<'tcx> {
     /// A tuple is WF only if its middle elements are `Sized`.
     TupleElem,
 
-    /// Must satisfy all of the where-clause predicates of the
-    /// given item.
-    WhereClause(DefId),
-
-    /// Like `WhereClause`, but carries the span of the
-    /// predicate when it can be identified.
-    SpannedWhereClause(DefId, Span),
-
-    /// Like `WhereClause`, but carries the `HirId` of the
-    /// expression that caused the obligation, and the `usize`
-    /// indicates exactly which predicate it is in the list of
-    /// instantiated predicates.
-    WhereClauseInExpr(DefId, HirId, usize),
-
-    /// Combines `SpannedWhereClause` and `WhereClauseInExpr`.
-    SpannedWhereClauseInExpr(DefId, Span, HirId, usize),
+    /// Represents a clause that comes from a specific item.
+    /// The span corresponds to the clause.
+    WhereClause(DefId, Span),
+
+    /// Like `WhereClause`, but also identifies the expression
+    /// which requires the `where` clause to be proven, and also
+    /// identifies the index of the predicate in the `predicates_of`
+    /// list of the item.
+    WhereClauseInExpr(DefId, Span, HirId, usize),
 
     /// A type like `&'a T` is WF only if `T: 'a`.
     ReferenceOutlivesReferent(Ty<'tcx>),